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Products => Test Equipment => Topic started by: resistcircuitresist on April 07, 2012, 07:47:37 pm

Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: resistcircuitresist on April 07, 2012, 07:47:37 pm
Hey guys, new to the forum, so please don't castrate me if I've posted in the wrong section.


Im looking for a good bench power supply or kit with lcds that has constant current and voltage modes.

I have been looking at something like this http://www.uni-trend.com/UTP3701.html (http://www.uni-trend.com/UTP3701.html)

Any feedback or recommendations....... Also are there power supplies that also measure current draw as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: electronwaster on April 07, 2012, 10:39:25 pm
Hi there,

I am a beginner so take everything I say with a shovelful of salt.

It looks like a very neat power supply, but I just searched around can't find anywhere that publishes a price, so it's hard to say whether it is good value.

You asked about monitoring current draw, well any single channel power supply with 2 screens will be showing you voltage and current. If it's constant voltage, constant current, as you mentioned, it should show you what current is being drawn. Only the very basic and cheap kits (e.g. LM317 based) will not show you the current being drawn.

The standard advice from the experts is to go for an old or new HP/Agilent (same products, company buyout, I believe). e.g. http://www.ebay.com.au/itm/190663291908?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_500wt_949 (http://www.ebay.com.au/itm/190663291908?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_500wt_949) I would go for a big Agilent supply if I had plenty of money.

It seems that you can also get trusty old power supplies from other smaller manufacturers for pretty good money, and for a lot of them, the schematics are available and are usually simpler to follow than the complicated new stuff.

I just (yesterday) bought a Farnell dual output 0-30V, 0-2A power supply with digital readout and constant current and constant voltage mode for $155. I do have to pay $60 for shipping because I don't live on the mainland of Australia, but that's true for me with any power supply. This is much cheaper than the $200-300 for the HP supply, and it has much more output (120W output vs 30W), and with luck it will all work and be of good quality.

If you are not absolutely wedded to the idea of digital output (I am too), there are lots of analogue output supplies going for much less on ebay. The circuitry could be identical, but getting a precision reading would require 2 multimeters in parallel and series, during use.

electronwaster

Edit: I forgot to mention, there are two power supply projects going on at the moment: Dave (the guy in the videos on the eevblog youtube channel) has a video series of about 10+ videos describing the design of a power supply he is making for production. I believe these will be a kit. They won't be available for at least a couple of months though (That is a guess, I'd love to know for sure)

Also Richard (forum username amspire) is designing a kit (check the forum) that will be slightly simpler, and available for/with through-hole components (easier for me to solder), and it won't require the use of a microcontroller. This is great for me as I spent several years as a programmer, and am sick of it :-) I want analog!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 08, 2012, 04:11:58 pm
This has been discussed at eevblog for quite a bit, but here's a summary of key points so you can search the archives.

Beware of Chinese branded supplies, don't judge quality by appearance.  PSU must provide clean DC power before anything else.  Even within brand names, quality control can vary. 

Choose between linear: capable of cleanest output but less efficient and thus big, heavy and bulky, versus switching mode, high power but noisier, but more efficient and compact size. 

See Agilent's papers on how to choose and evaluate PSU, to give you a benchmark to compare the others.

http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=856757&nid=-35673.0.00&id=856757 (http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=856757&nid=-35673.0.00&id=856757)

Digital programmability: while convenient it can make the output noisier than a manual one, particularly on lesser branded supplies.

FWIW there are many lab grade very high quality PSU sold on eBay for under what they are really worth, its just a question of waiting for the deal and knowing how to spot a dud from a gem.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 08, 2012, 05:22:49 pm
Just got a Power designs 2010 in very nice condition for $60.00 on ebay today.  Anxious to see how it performs.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 09, 2012, 05:09:30 pm
Nice!  Happy for you.  I posted elsewhere how good it is, and unusual.  They don't make PSU of this caliber since the early 1980s, and the only other one who competed in the category of "precision power supplies was an short running HP series.

If you finish your review before I do, please post your findings on a new thread, and I'll add to it.  I have 2 units currently being tested, and one more enroute. 

Some tidbits I'll string together later on, and add to a separate thread about this very nice PSU.

One unit is holding to 2ppm accuracy going on 100+ hours now of testing.  Its incredible.  However, while the dials are calibrated the linear adjust pot, a 100 ohm 10 turn Bournes, is erratic and can vary 300-500uV the knob setting!  Fairly easy to clean, adjust or change.  But, even if left as is its impressive setting output voltage to uV level and then pumping out 1A or so, and watch it hold to this value!  The unit came from a Boeing factory lab and looks like its been kept in better environmental conditions than the next supply.

The other unit is older and while it appears to be in pristine shape, there's rust on the outer body.  The dials are off 5mV, and bobbles in the uV, but the bourns pot is good.  Its 48hrs and its wandering +/-10uV, still very good for any PSU.   Its very likely oxidation or contaminants on the contacts of the rotary switch, from the environment it either worke din or was stored in.

Ripple check via a floating scope at it max 5mV/div show flat line up to 1A draw.  Superb for an old, or any age, PSU.

Power Designs have linear PSU that are not labeled "precision"; they have the similar specs as most any good quality stand alone supplies available today like the Agilent 36xx family.

Finally, look at this photo of Jim Williams' desk, note his PSU at lower left, with the "pd" symbol, and the signature aluminum face plate style with orange knobs, that's a Power Designs dual tracker.

(http://farm8.staticflickr.com/7183/6926146703_7b443c231f_b.jpg)


Just got a Power designs 2010 in very nice condition for $60.00 on ebay today.  Anxious to see how it performs.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 11, 2012, 02:25:28 pm
Just got a Power designs 2020 (20V 2A other specs same as 2005) in excellent condition for $85.00 on ebay today.  They are hiding in many places on ebay.  A simple "Power Designs" search does not show them all.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 11, 2012, 03:04:33 pm
You bought another?  Good for you!  I'm watching many of them, so you must be the one buying some as I see only single buyers on 2 units in the past week  ;) ... but if our review means anything later on, it could be hard to find cheaply.  Enjoy!

There are several generations of the precision model line.  The most modern are fairly ugly, with plastic bodies, and pricey.  Not sure why.  This design looks fairly 1980s, probably about the time PD started to fall into hard times.

(http://i.ebayimg.com/14/!BqYt!Dg!Wk~$%28KGrHqYH-D4Eu,Uf!0ErBLvh3tN5V!~~_1.JPG?set_id=8800005007)

Service, user and schematics for the 2005, 2010, 5020 and C500 are available as pdfs.  The schematics show some of the designs are so simple, its amazing such stability can be had so simply.
Likewise,  many of the popular general PD PSU have manuals, such as that pictured in the Jim Williams post.

Their name, "Power Designs" can make it hard to search, since its common search terms.  Add the word 'precision' helps narrow it down.



Just got a Power designs 2020 (20V 2A other specs same as 2005) in excellent condition for $85.00 on ebay today.  They are hiding in many places on ebay.  A simple "Power Designs" search does not show them all.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: olsenn on April 11, 2012, 03:20:04 pm
I own a BK Precision GPS-4303 PSU which I absolutely love. It is a 4 channel power supply, but you can get a 2 or 3 channel one for cheaper (around $200 - $400).

One thing I would like to mention as you say you are a beginner, is don't expect to find a PSU that offers quality constant current operation. When we refer to setting the current on a PSU it means the maximum current. It is always the voltage that is kept constant, and Ohm's Law can be used to determine how much current that will yeild (I = V/R). If you set the voltage to a greater value than can be achieved while maintaining the max current dialed in, then effectively it will be a constant current source, but don't rely on this; it will over/under shoot and may fail altogether.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: chimera_786 on April 11, 2012, 06:31:05 pm
my two cents: make on your self. It will teach you a lot. If you want help, pm me and we can start a new thread!  8)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 11, 2012, 06:54:13 pm
You bought another?  Good for you!  I'm watching many of them, so you must be the one buying some as I see only single buyers on 2 units in the past week  ;) ... but if our review means anything later on, it could be hard to find cheaply.  Enjoy!

This was the first. I was the only bidder  http://www.ebay.com/itm/251031626964?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 (http://www.ebay.com/itm/251031626964?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649)

This was the second. Was asking $119.99 I offered $85.00 and they took it.  http://www.ebay.com/itm/120758873482?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 (http://www.ebay.com/itm/120758873482?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

There are many in much worse condition and more money I was very fortunate thanks to your heads up on these supplies :)

Service, user and schematics for the 2005, 2010, 5020 and C500 are available as pdfs.  The schematics show some of the designs are so simple, its amazing such stability can be had so simply.
Likewise,  many of the popular general PD PSU have manuals, such as that pictured in the Jim Williams post.

saturation,  do you have links to these pdfs?  I have looked some and only found them available for sale not free.
Thanks, robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 11, 2012, 08:37:07 pm
Yes, to all.

I know those 2, just know the second one you won has a broken switch to move between 10V and 20V range, that switch is vintage aluminum handled locking pull to set type.  But its easy to substitute until you can find a matching replacement.

There are other units that have not been put back into auction that are in my tracking list.  They should be back shortly.

2005: Paul Rako's site.  He wrote for EDN, and now works for analog.

http://www.rako.com/Articles/29.html (http://www.rako.com/Articles/29.html)

2010, 5020, and C500

https://docs.google.com/viewer?a=v&q=cache:EwpcBMGQ5TAJ:128.238.9.201/~kurt/manuals/manuals/Other/POWER%2520DESIGNS%25202020B,%25205020,%2520C500%2520Instruction.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESgOKHKiERW-JexT4B1lKdgXdxFrlR3FKBaAISArSRNrlmm-L65VRQh2WZMvUBY3QvNaKRhZXi3nvdJuMMzLNhgGF1Zjzdz0wmT83-bRw-oCoH3jyU819g4ik3Z5_13PKKNwF4RS&sig=AHIEtbT9w8oh_e9PK_kT7JD8rqPC1kPWRA (https://docs.google.com/viewer?a=v&q=cache:EwpcBMGQ5TAJ:128.238.9.201/~kurt/manuals/manuals/Other/POWER%2520DESIGNS%25202020B,%25205020,%2520C500%2520Instruction.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESgOKHKiERW-JexT4B1lKdgXdxFrlR3FKBaAISArSRNrlmm-L65VRQh2WZMvUBY3QvNaKRhZXi3nvdJuMMzLNhgGF1Zjzdz0wmT83-bRw-oCoH3jyU819g4ik3Z5_13PKKNwF4RS&sig=AHIEtbT9w8oh_e9PK_kT7JD8rqPC1kPWRA)

More, Courtesy of KO4BB [ many thanks! Curt]:

http://www.ko4bb.com/ (http://www.ko4bb.com/)

[ the above is the main link, but he has far more manuals and not indexed on the main site]

http://128.238.9.201/~kurt/manuals/manuals/Other/ (http://128.238.9.201/~kurt/manuals/manuals/Other/)

of interest:

POWER DESIGNS 2005A Technical Data.pdf
POWER DESIGNS 2015R Instruction.pdf
POWER DESIGNS 2020B, 5020, C500 Instruction.pdf
POWER DESIGNS 5015T Instruction.pdf
POWER DESIGNS TB343A Instruction.pdf
POWER DESIGNS TP325 Technical Data.pdf
POWER DESIGNS TP340A Instruction.pdf
POWER DESIGNS TW347D, TW5005D, TW6050D Instruction.pdf
POWER DESIGNS TW347D,TW5005D,TW6050D Instruction.pdf


Enjoy.


This was the first. I was the only bidder ..
This was the second. Was asking $119.99 ..

There are many in much worse condition and more money I was very fortunate thanks to your heads up on these supplies :)

Service, user and schematics for the 2005, 2010, 5020 and C500 are available as pdfs.  The schematics show some of the designs are so simple, its amazing such stability can be had so simply.
Likewise,  many of the popular general PD PSU have manuals, such as that pictured in the Jim Williams post.

saturation,  do you have links to these pdfs?  I have looked some and only found them available for sale not free.
Thanks, robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 12, 2012, 02:44:27 am
saturation,  thanks for the help.  I still need to find the 2010 manual.  The googledocs was for 2020 not 2010 (I am not complaining :)).
I got the first unit (the 2010) today.  Wow, as Dave would say "pure electronic equipment pornography" As a machinist I especially appreciate the quality of the knobs and dials. Voltage output is well within spec and front and rear panel are mint condition. Only the case paint needs a little help but I cant believe I got this for $60.00
Thanks again for all the info.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: resistcircuitresist on April 13, 2012, 03:02:20 am
I own a BK Precision GPS-4303 PSU which I absolutely love. It is a 4 channel power supply, but you can get a 2 or 3 channel one for cheaper (around $200 - $400).

One thing I would like to mention as you say you are a beginner, is don't expect to find a PSU that offers quality constant current operation. When we refer to setting the current on a PSU it means the maximum current. It is always the voltage that is kept constant, and Ohm's Law can be used to determine how much current that will yield (I = V/R). If you set the voltage to a greater value than can be achieved while maintaining the max current dialed in, then effectively it will be a constant current source, but don't rely on this; it will over/under shoot and may fail altogether.

Thanks for the information about the current settings. The reason I'm interested in that setting is to test circuit designs under less than ideal power. Ie failing or low battery.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 13, 2012, 03:53:35 pm
You're welcome.  The 2010 and 2020 are very similar, but mea culpa, I made that presumption.  I wouldn't be surprised if they are for the most part identical except for specifications for the main power elements: diodes, transformer, and power transistors.   Since the components are heavily derated, its even possible most if not all are identical except for the transformer.  So, until one can be located, the 2020 manual could serve as a close guide.


saturation,  thanks for the help.  I still need to find the 2010 manual.  The googledocs was for 2020 not 2010 (I am not complaining :)).
I got the first unit (the 2010) today.  Wow, as Dave would say "pure electronic equipment pornography" As a machinist I especially appreciate the quality of the knobs and dials. Voltage output is well within spec and front and rear panel are mint condition. Only the case paint needs a little help but I cant believe I got this for $60.00
Thanks again for all the info.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 13, 2012, 04:40:35 pm
I agree about the manual similarity and that these power suppies are unbelievable. 
100mV setting.   stat mode on the 8846A 6.5 digit 100nplc digital filter
 
1 hour AVG 99.99839 mV    1.75 uV min-max span   SD of .392 uV
3 hour AVG 99.99873 mV    2.93 uV min-max span   SD of .667 uV
6 hour AVG 99.99935 mV    3.33 uV min-max span   SD of .855 uV

My 8846A shorted input DC 152 hr stability min-max span  is 1.08 uV ! :o

Full 1A load output ripple measured with 8846A on AC is 15.8 uV max.
 I know this is way out of the guaranteed specs of the 8846A but I did some crude testing here https://www.eevblog.com/forum/product-reviews-photos-and-discussion/low-level-ac-performance-of-fluke-8846a/msg76514/#msg76514 (https://www.eevblog.com/forum/product-reviews-photos-and-discussion/low-level-ac-performance-of-fluke-8846a/msg76514/#msg76514) that shows it is way better than the specs and does not put out bogus numbers down here like some meters aparently do.

I don't know about you but I might replace that mV pot with a 10 turn and a turns counter. It is very hard to set 1uv levels with that 1 turn pot.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 13, 2012, 05:36:59 pm
WOW!  That's fantastic.  Much better values that mine. 

Yes, I would consider changing the pot to a 10 turn, do you have a source for a turns counter?

I also have a PD 5020 which uses a 100 ohm 10 turn Bournes, you can set uV levels for a 50V output!, but the pot needs servicing or replacement.  It has a beautiful machined turns counter, with lock and mV vernier scale for setting 100uV increments.  Its erratic currently, but its stable once its settles.  Its tracked by the 3rd 3456a in the bottom photo.

(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23195;image)



Some porn for you, 2020B x 2, above and a 5020 at bottom:

(https://lh3.googleusercontent.com/-44HqIyf-Pbw/T4het5mHqLI/AAAAAAAAAgA/OMCMPdSpQrU/s720/2012-04-12_11-53-15_183.jpg)

Tracking output going on 4+ days.  That's variance, to get SD square root those numbers.  Each 3456a is tracking one PSU.  That's about 13uV, 5uV and 4uV SD for each unit.  For 99% confidence interval multiple each by 6 [3 SD above and 3 SD below the mean], so its roughly spans 78uV, 30uV and 24uV.  This is as close I've seen a PSU get battery like variation.

(https://lh3.googleusercontent.com/-vtT7u-PHWCY/T4hepZH1_7I/AAAAAAAAAgI/WYhtG6YiAHU/s720/2012-04-12_11-54-05_656.jpg)


I agree about the manual similarity and that these power suppies are unbelievable. 
100mV setting.   stat mode on the 8846A 6.5 digit 100nplc digital filter
 
1 hour AVG 99.99839 mV    1.75 uV min-max span   SD of .392 uV
3 hour AVG 99.99873 mV    2.93 uV min-max span   SD of .667 uV
6 hour AVG 99.99935 mV    3.33 uV min-max span   SD of .855 uV

My 8846A shorted input DC 24hr stability min-max span  is 1.15 uV ! :o

Full 1A load output ripple measured with 8846A on AC is 15.8 uV max.
 I know this is way out of the guaranteed specs of the 8846A but I did some crude testing here https://www.eevblog.com/forum/product-reviews-photos-and-discussion/low-level-ac-performance-of-fluke-8846a/msg76514/#msg76514 (https://www.eevblog.com/forum/product-reviews-photos-and-discussion/low-level-ac-performance-of-fluke-8846a/msg76514/#msg76514) that shows it is way better than the specs and does not put out bogus numbers down here like some meters aparently do.

I don't know about you but I might replace that mV pot with a 10 turn and a turns counter. It is very hard to set 1uv levels with that 1 turn pot.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 13, 2012, 07:12:06 pm
I just switched to 1V instead of .1V and the min-max span is 16uV with a SD of 4.6uV for 2 hours run time. So it looks like it may be a percentage of output voltage just like the spec implies.  What voltage are you testing at?

This is the turns counter I quickly found. This is the model with no brake. It is available with brake also.
http://www.alliedelec.com/search/productdetail.aspx?SKU=70125994 (http://www.alliedelec.com/search/productdetail.aspx?SKU=70125994)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 13, 2012, 07:37:03 pm
Thanks for the link! that saved a lot of time.  It looks like Kilo is the source for some of PD knobs as its a dead ringer for what's on these, 30+ years later.  Those knobs cost over 50% the cost of the PSU  :o

For the picture, I used 0.1V too, adjusted to 100.000 00 mV.  I think a good fraction of the instability is coming from the pots as they contribute more in adjustments at lower output voltages.  At higher voltages, they are less contributory so I get values closer to yours, 1-10uV, e.g. when I set it to 1V SD is only 0.5uV.

FYI, cleaning precision switches use Dexoit 5 or equivalent as other sprays may leave residues that alter contact resistance.  Its similar to maintenance on older voltage sources that use rotary switches for resistance decade dividers:

http://www.krohn-hite.com/htm/technotes/technical_note.htm#Technical%20Note%20#012 (http://www.krohn-hite.com/htm/technotes/technical_note.htm#Technical%20Note%20#012)



I just switched to 1V instead of .1V and the min-max span is 16uV with a SD of 4.6uV for 2 hours run time. So it looks like it may be a percentage of output voltage just like the spec implies.  What voltage are you testing at?

This is the turns counter I quickly found. This is the model with no brake. It is available with brake also.
http://www.alliedelec.com/search/productdetail.aspx?SKU=70125994 (http://www.alliedelec.com/search/productdetail.aspx?SKU=70125994)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 13, 2012, 07:59:13 pm
@ saturation
I have deoxit 5 for the switches and also gold, and I use the fader lube for pots. but its good to get a thumbs up on using it. I get the bottled liquid instead of the spray.  If I need to spray it I put a drop or two in a fine solder paste dispensing needle and put it on my paste dispenser and give it a 70psi blast. With that you can get into places the spray cans cant touch.

Should we start a new thread for these PD suppies and ask for the PD related stuff here to be moved/copied to it?
10 volts is showing 16uv span and 2.3uV SD for 15 mins
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: chrome on April 13, 2012, 08:29:00 pm
(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23195;image)

Damn, 10 Mega Volt
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 13, 2012, 08:31:58 pm
And that is the least signicant digit!!!!!! :o
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 14, 2012, 12:58:25 pm
Those are great ideas for applying deoxit, you think the spray can with nozzle is still not fine enough?

As for moving the thread, yes, why not?  I still have a way to go with getting mine up to factory shape, and a business trip coming up so I won't be able to post tear downs for at least a month. 

I think these supplies are very unique and need a detailed going over.  With the available schematic, and with interest shown by readers in Dave's recent videos on PSU designs, this supply would make a great DIY build.  Why build any LM317 based supply if its easier to buy one and mod it for better performance?  Not so with these supplies, so far.  DIY effort would be worth it because these designs are no longer produced so building is the only alternative; any patents on the circuit would be expired by now.   

Further, if the eBay supplies are exhausted, is unavailable or priced too high to ship to other countries, or if prices rise due to any interest we generate on the thread, it will remain cost effective and well worth one's time to build.




@ saturation
I have deoxit 5 for the switches and also gold, and I use the fader lube for pots. but its good to get a thumbs up on using it. I get the bottled liquid instead of the spray.  If I need to spray it I put a drop or two in a fine solder paste dispensing needle and put it on my paste dispenser and give it a 70psi blast. With that you can get into places the spray cans cant touch.

Should we start a new thread for these PD suppies and ask for the PD related stuff here to be moved/copied to it?
10 volts is showing 16uv span and 2.3uV SD for 15 mins


Yes, that an error they've propagated through decades on the precision series PSU, methinks its because their stencil is all upcase and in the old days it wasn't as cheap or easy to change on demand ;)


Damn, 10 Mega Volt
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 14, 2012, 09:44:45 pm
Those are great ideas for applying deoxit, you think the spray can with nozzle is still not fine enough?

I don't have a problem with spray cans. I just like the versatility and cost effectiveness of the bottles or tubes. You never run out of propellant pressure with my method and you can swab every last drop out of the bottle. I keep a micro brush applicator http://www.microbrush.com/automotive/products/microbrush/index.asp (http://www.microbrush.com/automotive/products/microbrush/index.asp) with each bottle for non spray application. I have more control with the hypodermic/paste dispenser method as to the amount and where it goes. a carefully located drilled source (and drain if needed) micro holes in a switch or pot can allow cleaning and lube without disassembly. You can put as much IPA or your favorite cleaning solvent into a glue dispenser syringe as you feel appropriate and inject it under pressure. Then take the piston out of the syringe and blow it out with just the air. Then blast the conditioner or lube in.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 15, 2012, 03:54:38 pm
Thanks for tips, robrenz, and those links!

Here's another test you can run on the PD supplies, current sourcing.  An idea current source is fully independent of output voltage, so in theory it outputs full current near "zero" volts.

In reality most supplies can't.  However, the 2020B can pull rated amps, >2.2A on my test, set at 200mV, 1.3A at 100mV, and still gradually down the line as you approach zero VDC.

By comparison, my Chinese Mastech supply requires 1.0VDC to output its rated 3A, and drops quickly to 30mA at 600mV.




Those are great ideas for applying deoxit, you think the spray can with nozzle is still not fine enough?

I don't have a problem with spray cans. I just like the versatility and cost effectiveness of the bottles or tubes. You never run out of propellant pressure with my method and you can swab every last drop out of the bottle. I keep a micro brush applicator http://www.microbrush.com/automotive/products/microbrush/index.asp (http://www.microbrush.com/automotive/products/microbrush/index.asp) with each bottle for non spray application. I have more control with the hypodermic/paste dispenser method as to the amount and where it goes. a carefully located drilled source (and drain if needed) micro holes in a switch or pot can allow cleaning and lube without disassembly. You can put as much IPA or your favorite cleaning solvent into a glue dispenser syringe as you feel appropriate and inject it under pressure. Then take the piston out of the syringe and blow it out with just the air. Then blast the conditioner or lube in.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 15, 2012, 04:04:04 pm
Some comments for beginners, such a supply is often not a good supply as if it performs this way the voltage regulation will also certainly be poor, or there are other flaws in the design.  Just test of response time will show the over/under shoot or other failures.

A constant voltage source can be converted to a constant current source, its the essence of Norton's theorem.   Thus, the quality of voltage regulation is also proportionate to its capability in current regulation and vice versa.


I own a BK Precision GPS-4303 PSU which I absolutely love. It is a 4 channel power supply, but you can get a 2 or 3 channel one for cheaper (around $200 - $400).

One thing I would like to mention as you say you are a beginner, is don't expect to find a PSU that offers quality constant current operation. When we refer to setting the current on a PSU it means the maximum current. It is always the voltage that is kept constant, and Ohm's Law can be used to determine how much current that will yield (I = V/R). If you set the voltage to a greater value than can be achieved while maintaining the max current dialed in, then effectively it will be a constant current source, but don't rely on this; it will over/under shoot and may fail altogether.

Thanks for the information about the current settings. The reason I'm interested in that setting is to test circuit designs under less than ideal power. Ie failing or low battery.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: jpc6204 on April 15, 2012, 09:43:24 pm
Dave has listed some supplies that he recommends under his Amazon tab:

http://www.eevblog.com/amazon/ (http://www.eevblog.com/amazon/)

There you will see:

1. BK Precision Power Supply, 1670A, Triple Output, Digital
2. Extech 382260 80 Watt Switching Mode DC Power Supply
3. Mastech TRIPLE LINEAR DC POWER SUPPLY 30V 5A HY3005F-3

I've been drooling over the Mastech supply for a while now.

Echo the fact that building your own supply is always a good learning experience if you haven't don so yet.


Jeff...

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 17, 2012, 11:49:18 am
Here's another test you can run on the PD supplies, current sourcing.  An idea current source is fully independent of output voltage, so in theory it outputs full current near "zero" volts.

In reality most supplies can't.  However, the 2020B can pull rated amps, >2.2A on my test, set at 200mV, 1.3A at 100mV, and still gradually down the line as you approach zero VDC.

By comparison, my Chinese Mastech supply requires 1.0VDC to output its rated 3A, and drops quickly to 30mA at 600mV.

I tried that on my 2010 and 2020 and got similar results to you.  Then I thought let me see what my Mastech 3030 triple supply does.  It only required 6.5mV to drive the full 3A.  A Chinese unit performing better than the PD supplies  :o how can that be? Then I realized I shorted the output on the Mastech with my 3" heavy 8awg banana jumpers I made for paralleling the outputs.  When I tested the PD units I used a 7" long piece of 20awg solid wire that was laying around. I retested the PD units with the heavy jumper and They both drive full amperage at approx. 6mV also.  It makes sense to me now, the power supply has to put out at least the voltage drop across the short. So the 6.5mV at 3A means the total "short" resistance seen at the output was 2.16mOhm.  My lesson learned,  use very short shorts.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 17, 2012, 10:53:56 pm
Nice!  I did the test shorting the inputs with 1252a DMM and read the current of it, so it was also working against the voltage drop across the DMM.  I did this because the built in ammeters need to be recalibrated.  I presume you were reading the current off the PSU built in ammeters?  I'll try that later on and report back.  Nevertheless, your results are even more impressive that what I reported earlier.  Its a more ideal response; maybe my Mastech isn't as bad as it looks too [ in which case, kudos to Mastech!]


Here's another test you can run on the PD supplies, current sourcing.  An idea current source is fully independent of output voltage, so in theory it outputs full current near "zero" volts.

In reality most supplies can't.  However, the 2020B can pull rated amps, >2.2A on my test, set at 200mV, 1.3A at 100mV, and still gradually down the line as you approach zero VDC.

By comparison, my Chinese Mastech supply requires 1.0VDC to output its rated 3A, and drops quickly to 30mA at 600mV.

I tried that on my 2010 and 2020 and got similar results to you.  Then I thought let me see what my Mastech 3030 triple supply does.  It only required 6.5mV to drive the full 3A.  A Chinese unit performing better than the PD supplies  :o how can that be? Then I realized I shorted the output on the Mastech with my 3" heavy 8awg banana jumpers I made for paralleling the outputs.  When I tested the PD units I used a 7" long piece of 20awg solid wire that was laying around. I retested the PD units with the heavy jumper and They both drive full amperage at approx. 6mV also.  It makes sense to me now, the power supply has to put out at least the voltage drop across the short. So the 6.5mV at 3A means the total "short" resistance seen at the output was 2.16mOhm.  My lesson learned,  use very short shorts.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 18, 2012, 12:58:31 pm
So just to prove to myself that the short resistance is a big deal in CC testing I made a super short pictured here.  .625 diameter tellurium copper with gold plated beryllium copper banana jacks.

(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23367;image)

This is the 3" heavy 8awg banana jumpers I used in my first test described before.

(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23369;image)

I checked the calibration of the amp meter on the power supply and it is spot on. I set the current limit to 1 Amp using my fluke 87 but had to use a higher voltage because of the voltage drop across the shunt in the 87.  Left the current setting alone, plugged in the super short, dialed down the voltage until it just bumped the 1 Amp reading and measured the output voltage with the 8846A.  Sub 1mV,  that's 5mV less than the 3" heavy 8awg banana jumper. 

EDIT#1: I checked the 2020B at 2 amps and got 1.39mV but noticed you need to wiggle the shunt to get the lowest contact resistance/voltage. So I went back to the 2010 at 1 amp and wiggled for lowest resistance and got 0.7mV instead of the .8749mV. So it looks like .7mv/Amp.  Becoming obvious that Milli and micro Ohms matter down here.

EDIT#2: So the effective resistance of the "3" heavy 8awg banana jumper" is 0.00216 Ohm and the "super short effective resistance is 0.000695 Ohm. Only 0.00147 Ohm difference.

Sorry for the crap picture, hand held long exposure to get the whole reading of the VFD
(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23373;image)

(https://www.eevblog.com/forum/beginners/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23371;image)

So I wondered why the PS current measuring shunt (.2 Ohm) voltage drop isn't showing up in the output voltage? I think it is because the voltage sense is after the shunt voltage drop in the power supply. 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SoftwareSamurai on April 18, 2012, 05:44:48 pm
3. Mastech TRIPLE LINEAR DC POWER SUPPLY 30V 5A HY3005F-3

I've been drooling over the Mastech supply for a while now.

What about the Mastech HY1803D?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on April 18, 2012, 05:58:25 pm
Robenz, I think you are measuring the resistance of the posts themselves, rather than anything else.........

And there I though using a thick copper foil as a zero ohm resistor was good enough........
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 18, 2012, 06:19:01 pm
Robenz, I think you are measuring the resistance of the posts themselves, rather than anything else.........

And there I though using a thick copper foil as a zero ohm resistor was good enough........

SeanB, I agree, I am making a set of kelvin probes for my IET LOM-510A micro Ohm meter
http://www.ietlabs.com/decaderes-1/resistance-meter/lom-510.html (http://www.ietlabs.com/decaderes-1/resistance-meter/lom-510.html)
and as soon as their done I will be able to measure the resistance directly to 1 micro ohm resolution +/- (0.02% rdg. + 4 micro Ohm) accuracy. I then will be able to actually measure the  short resistance and separate out the jack resistances from the bar itself.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 20, 2012, 05:02:22 pm
I did prelim tests with a just a shorting bar and my results are as you demonstrated with yours: the PD were able to source its rated current, 2ADC, for my 3 units measured at at 6mV, 2mV, 3mV, as compared to when I measured current with the DMM.  I then double checked the output voltage on the terminals with the DMM.  These units are a 2020B x 2, and a 5020.

My 3030D Mastech, alas, still outputed 3A at ~800mV.  Clearly, this was not designed as well as your version.

Nevertheless, its clear from the more meticulous checks you've made that the PD can output close to an ideal current source, that is its output is ~ independent of the voltage across the outputs, as whether its approaching zero volts up to its rated maximum output voltage, the rated current can be pumped out as you desire.  Awesome!

As resistances is getting fairly small, the jacks or any other minor series resistance are starting to play bigger roles in the voltage drop measured.  I think you can still push it to see what the theoretical minimum can be, but driving at 1-6mV output voltage at 1-3A is far from what any circuit I know can be powered!  So, I think the point is very well made at this level.

In my units, the still uncleaned adjustment pots are likely playing large roles in not getting adjustment down further or improving the output stability.  So, it should be interesting to revisit the tests when the units are spruced up.


So just to prove to myself that the short resistance is a big deal in CC testing I made a super short pictured here.  .625 diameter tellurium copper with gold plated beryllium copper banana jacks.
...

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: krivx on April 26, 2012, 01:35:24 pm
Can you the Power Designs supplies sold in the US run off 230V 60Hz? Or is a step-down transformer required? Getting a supply from the states to Europe might be worth it for me if I can use it without much modification or having to buy extra equipment.

edit: After looking at a few manuals, it seems some models have a jumper on the power transformer for 240V operation and some may not. If anyone knows for sure please let me know.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 26, 2012, 02:00:41 pm
Hello krivx

I have not tested it personally.  But the manual for the 2020B, 5020 and C500 state it will work from 47 Hz to 440 Hz; a jumper has to be set internally for 240V, so spec wise its ready for EU.

You may have to check manuals for any specific model of this level of supply, as the older ones can be different.  Except voltage, many PD supplies before 1980 labeled the key specs on the rear of the units.

I have an ongoing discussion on another forum about obtaining more manuals and schematics.  The fellows are doing it on their own time, so patience, please.

As the users post them, they will be here.  Some are already loaded:

http://www.ko4bb.com/manuals/ (http://www.ko4bb.com/manuals/)


Can you the Power Designs supplies sold in the US run off 230V 60Hz? Or is a step-down transformer required? Getting a supply from the states to Europe might be worth it for me if I can use it without much modification or having to buy extra equipment.

edit: After looking at a few manuals, it seems some models have a jumper on the power transformer for 240V operation and some may not. If anyone knows for sure please let me know.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: krivx on April 26, 2012, 03:29:05 pm

As the users post them, they will be here.  Some are already loaded:

http://www.ko4bb.com/manuals/ (http://www.ko4bb.com/manuals/)


Thanks, there are quite a few manuals here awaiting approval. http://www.ko4bb.com/manuals/index.php?dir=10%29_Recent_Uploads (http://www.ko4bb.com/manuals/index.php?dir=10%29_Recent_Uploads)

These could be very helpful! I'll take a look through them when they're available and start asking for shipping quotes for suitable models. Even with shipping costs some of these supplies are still bargains.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 26, 2012, 05:59:53 pm
There is mirror server, here files are available, its not secret its indexed on google:

http://128.238.9.201/~kurt/manuals/manuals/Other/ (http://128.238.9.201/~kurt/manuals/manuals/Other/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: krivx on April 26, 2012, 09:09:07 pm
It looks like the newer models have a transformer jumper, the older ones do not. Thanks for that link, it could save a lot of hassle.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on April 30, 2012, 05:01:07 pm
I bought 2 later model 2005 units off ebay in "not functioning" condition.  They lit up but did not output any voltage. Both units had the 1 amp DC fuse (internal) blown but seem ok after fuse replacement.  (good thing since that is about the extent of my troubleshooting  skills) ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 03, 2012, 01:09:15 pm
Here are some pics of one of the two 2005's.  I tried doing a voltage cal "as is" and couldn't get to zero with the zero adjust pot.  Did an electrical cleaner spray and air blast on all the gang switch contacts and then used de-oxit on all the many many wipers on the gang switches.  Now the zero cal pot can get it to zero. Adjusted the 20V setting to 20.00000V

These are some random voltage checks using a 8846A 6.5 digit 24ppm meter. % error values do not include meter error. 
The stated accuracy for this supply is 0.1% +/- 1mV
SETTING    READING   % ERROR
20             20.00000         0%
15             15.00020        .0013
10 on 20    10.00046        .0046
10 on 10     9.99980         .002
5                5.00000         0
1                1.000116       .011
1.555555    1.555370       .011

AC RMS (no load) is 10.1uV so P-P would be 28.56uV
Spec is 100uV P-P

Stability is not as good as the 2010 I have.  The 2010 after 14 hours had a total min. max. span of 3.75uV and a SD of 763nV .  This 2005 is out of spec with a 1 hour min. max. span of 196uV.
EDIT: After a couple of hours on time the min.- max. span has dropped to 9.1uV with a SD of 2.5uV  for a half hour test. maybe electrolytics are reforming some?
EDIT2: No wonder they burn them in for 100 hours before calibration.  Recalibrated after about 4 hours of on time and a 2 hour stability test gave a min.- max. span of 5.95uV and a SD of 1.48uV

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23908;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23910;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23912;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23914;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23916;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23918;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23920;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=23922;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 03, 2012, 04:41:57 pm
MY GOD the parts looks orgasmic
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 03, 2012, 04:53:51 pm
The crazy part is that supply cost me $60.99 + shipping on ebay plus a $3.45 $0.37 fuse.  But the perfomance cannot be touched even by $400 to $600 modern supplies.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 03, 2012, 05:19:06 pm
The crazy part is that supply cost me $60.99 + shipping on ebay plus a $3.45 fuse.  But the perfomance cannot be touched even by $400 to $600 modern supplies.

Sure. Pity it's not like widely available. What's the weight like? Colossal or Lighter then expected?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 03, 2012, 05:35:23 pm
2005 weighs 9 pounds.  2020B weighs 13 pounds.  I only see 4 of the precision units on US Ebay currently.  Dont worry I am not buying any more of these.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 04, 2012, 12:16:05 pm
2005 weighs 9 pounds.  2020B weighs 13 pounds.  I only see 4 of the precision units on US Ebay currently.  Dont worry I am not buying any more of these.

I don't live in the states you see. Shipping can be a killer but i remembered they are precision power supplies and not general high power power supplies it makes sense.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 04, 2012, 05:53:52 pm
Tested one of the 2005 supplies for CC mode with the super short at its full 500mA.  Needed to set 1.3mV to get the full 500mA. Measured the voltage drop right where the banana plugs screw into the copper bar (probe tip touching the plug and the bar simultaneously). 3uV drop across the short itself.  The remaining voltage is dropped in the banana jacks and sockets getting to the copper bar. 

Did the same thing on the 2010 supply at 1A and needed 2mV to get there. Voltage drop across the copper bar was 6uV as expected.  So the actual copper bar is approximately 6uOhm when you don't count the banana plug resistances.

EDIT: measured the short bar resistance at the same locations with my microOhm meter and got 6uOhm also. Even though I calculate the copper resistance for the effective bar length at 1.85uOhm. This is the effect of the actual effective path of the current through the bar being a smaller cross sectional area than the bar itself.  I proved this out with a 4" square piece of copper .0625" thick.  Measured the resistance on one edge with the sense leads of the uOhm meter .5" apart.  The theoretical resistance for a cross sectional area of .0625" x 4"  .5" long is 1.32uOhm but the meter reads 13uOhm. The electric field does not uniformly spread out and use the whole cross sectional area, It takes the shortest path.  (sounds good but who knows if it is technically correct ::))
 
 It was interesting to see the voltage rise as I moved the probes on the banana jacks away from the copper bar and toward the power supply jacks. When I measured the voltage right at the face of the binding posts on the supply it is 1mV so the other 1mV (minus 6uV) is dropping on the  internal wiring up to the binding posts.

OK, I know I am obsessed with this but: It would be interesting to hook up the remote sense leads right at the junction of the banana jacks and the copper bar. I suspect then you could dial roughly 6uV on the 0-1 mV dial and drive the full 1A. All the  other voltage drops would be compensated for.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on May 05, 2012, 12:27:11 pm


You guys are a bad influence.  Look what I just got;
http://www.ebay.com/itm/200731066755?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 (http://www.ebay.com/itm/200731066755?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649)


I will report once it arrives. 

(http://img.auctiva.com/imgdata/7/2/7/6/3/6/webimg/556702759_o.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on May 05, 2012, 12:32:08 pm
Question.  Does anyone know what the difference is fromt he TW5005T model that I got compared to the TW5005W on Jim William's bench in the first page?

(http://farm8.staticflickr.com/7183/6926146703_7b443c231f_b.jpg)

The only difference I can spot is the pot for voltage selection.  Does the "W" model have a 10 turn pot and the "T" a dual pot setup with the fine adjustment on the inner dial?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 05, 2012, 02:37:37 pm
Nice buy! It looks like you are probably correct about the pot difference.  The manual for the "W" is on eBay for $25.00 and the manual links in this post only go to the "D" on the TW5005.  Just keep in mind the specs and performance that have been shown in this thread so far are for the precision versions with the decade voltage setting.  But the specs on the analog setting versions are extremely good also. It was good enough for Jim Williams, that says a lot.

I am definitely NOT implying don't post here if not a "precision" supply. I just want people to be aware of the difference.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on May 05, 2012, 07:05:45 pm
Thanks for the reply robrenz.

I'm a beginner and I don't have anything more accurate than a Fluke 87V so yeah I'll start a new thread once it arrives.  I looked around a lot and even for a beginner this bench power supply seemed like a bargain.  And yea my thinking was exactly that; "If it was good enough for Jim Williams..."
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 07, 2012, 05:28:45 pm
The second 2005 I got continued to blow the 1 amp fuse.  Three fuses later I see it happens when I move the current limit pot through its range and I noticed a spike in the needle on the amp gage. So it was the momentary open circuit on the pot that was spiking the current and blowing the  fuse.  So I took the pot apart to clean and lube but I kept getting a jump on my fluke87 ohms reading in roughly the same places. So half an hour later after ultrasonic cleaning and microscope inspection of every single turn of wire in the pot and still seeing the glitch in the pot travel. I finally realize the jump is the range change on the meter  (EDIT: from 400 Ohm to 4k Ohm range), not a open in the pot travel.  lock the range on the meter and no problem :-[
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 07, 2012, 08:18:45 pm
Hi robrenz,

I'm back.  Lots of catching up to do.  When you mention range change, that's means moving from 0-10V to 10-20V or vice versa, but if you don't touch the switch all is well?  I presume the current limiting is set at a value far lower than the fuse rating? 


The second 2005 I got continued to blow the 1 amp fuse.  Three fuses later I see it happens when I move the current limit pot through its range and I noticed a spike in the needle on the amp gage. So it was the momentary open circuit on the pot that was spiking the current and blowing the  fuse.  So I took the pot apart to clean and lube but I kept getting a jump on my fluke87 ohms reading in roughly the same places. So half an hour later after ultrasonic cleaning and microscope inspection of every single turn of wire in the pot and still seeing the glitch in the pot travel. I finally realize the jump is the range change on the meter, not a open in the pot travel.  lock the range on the meter and no problem :-[
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 07, 2012, 08:37:34 pm
The range change was on my fluke meter as I swept through the whole range of the 10k 1k pot.  The current limit pot was dirty and did go open as you moved it through the range. But when I had the pot apart and was checking the resistance before I put it together again I was thinking the blink when the range changed was a open circuit. So for half an hour at least I was searching for a problem that was not there.  When I locked the range on the meter the  pot was fine after cleaning.  Quite embarrassing :-[
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on May 07, 2012, 09:13:32 pm
The range change was on my fluke meter as I swept through the whole range of the 10k pot.  The current limit pot was dirty and did go open as you moved it through the range. But when I had the pot apart and was checking the resistance before I put it together again I was thinking the blink when the range changed was a open circuit. So for half an hour at least I was searching for a problem that was not there.  When I locked the range on the meter the  pot was fine after cleaning.  Quite embarrassing :-[

I bet you will never make that mistake again.  This is why experience in any field is so important.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 18, 2012, 03:43:17 pm
A PM I received from Paul Rako regarding his Power Design unit:

Saturation,

You have received a new Private message from Paul Rako with the subject: Re: Power Designs 2005 Precision DC Supply.


"The only problem my old Power Designs supply had was oxidation on the switch contacts. I removed that with De-Oxit  (http://www.caig.com/ (http://www.caig.com/)). It worked fine after that, but I hate to tell you, I sold it to a friend. For very accurate voltage creation you can use to check A to D converters, see my pal Mark Thoren's presentation on buffering a Deka-pot to give a precise output voltage: http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202 (http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202) "


http://www.rako.com/Articles/29.html (http://www.rako.com/Articles/29.html)

i think that's not bad at all for a unit >40 years old.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alm on May 18, 2012, 08:49:19 pm
The current limit pot was dirty and did go open as you moved it through the range.
Blowing fuses when a pot goes OC for a short time sounds like a design flaw to me. One should always assume that pots might go OC, especially the wire wound ones that might have a single bad turn.

For very accurate voltage creation you can use to check A to D converters, see my pal Mark Thoren's presentation on buffering a Deka-pot to give a precise output voltage: http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202 (http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202) "[/i]
Video doesn't work here. I guess it's that nice cheap DIY design requiring a $4k+ pot? Seems Paul is a bit out of touch with the people that have limited budgets.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 18, 2012, 09:35:21 pm
The current limit pot was dirty and did go open as you moved it through the range.

Blowing fuses when a pot goes OC for a short time sounds like a design flaw to me. One should always assume that pots might go OC, especially the wire wound ones that might have a single bad turn.

It might be, but a solution for this 1960-70s design was to protect the system with a fuse, rather than an active shut down.  Given how infrequently a bad turn happens in a precision pot it seems like a cost effective solution.  That the fuse didn't blow in years [ nor has my versions blown in all 3 units] and the units are 30+ years old is QED that design ethic was cost effecient and effective, I think.

For very accurate voltage creation you can use to check A to D converters, see my pal Mark Thoren's presentation on buffering a Deka-pot to give a precise output voltage: http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202 (http://www.edn.com/video/video.php/?bclid=1028763155&bctid=1026280202) "[/i]

Video doesn't work here. I guess it's that nice cheap DIY design requiring a $4k+ pot? Seems Paul is a bit out of touch with the people that have limited budgets.

Yes, I think its the same video, here mirrored on youtube:

Build your own laboratory precision voltage source - Linear Technology (https://www.youtube.com/watch?v=9KtJr7Jv16I#)

And yes, it does use that $4000 KV in a dial switch. 

(http://www.ietlabs.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/D/P/DP1211_20.jpg)

http://www.ietlabs.com/voltage-divider/esi-dp-1211-dp1311-voltage-dividers.html (http://www.ietlabs.com/voltage-divider/esi-dp-1211-dp1311-voltage-dividers.html)


The PD and even the Krohn Hite EDC 106 designs use resistance dividers in a similar approach as the Linear design, but their DIY rotary switch based dividers provide a >~ accuracy and precision at much less cost. 

In addition, given PD precision PSU availability via eBay, one can get a working product that not only provides accuracy similar to Linear's design, fully assembled, burned in, cost ~ 3% of a KV divider alone and source current like a bench PSU.  The buyer has to beware units are aged and will need a going through to insure its functionality, which so far reported, its has been.



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 24, 2012, 10:27:45 am
I have an model 2005 (old model), and I also had problem with the settings at first. The linearity was poor, a higher setting could result in a lower voltage for instance.

I cleansed the rotary switch contacts and now it works really well. It's linearity is good but the unit is uncalibrated. But I'm happy. The only problem I have is the current limitation, its not so stable. If I look on the schematics, its probably temp drift in the shunt resistor or the pot, as they are "non ovenized".

Do I recommend it? Yes. But only if you think its worth the bucks! I payed near $200 for the unit, shipping, customs, Posten's (Swedish postal services) ridiculous fees and have to walk for 1 km to lug it home. The unit in it self only cost me about $70 of the $200 if I remember correctly!  :-\
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 24, 2012, 11:32:54 am
Calibration is very easy and covered in the manual. Then it will agree with your best meter at 0V and 20V which is better than no calibration at all.  Make sure you use the corresponding manual. AFIK the one in the Paul Rako article is for the version with the large horizontal meter (2005). There is another one for the unit with the thin vertical meter (2005A).  From my experience let it warm up at least an hour before calibration. If you have not had it on much since you bought it I would let it burn in a couple of days straight before calibration. FWIW

Regards, robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: EEVblog on May 24, 2012, 11:43:53 am
I have a 110V PD 2005, and it seems to be in a bit crusty condition.
More to come on this I'm sure...

Dave.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 24, 2012, 11:48:35 am
Anxiously waiting  ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 24, 2012, 12:11:38 pm
Calibration is very easy and covered in the manual. Then it will agree with your best meter at 0V and 20V which is better than no calibration at all.  Make sure you use the corresponding manual. AFIK the one in the Paul Rako article is for the version with the large horizontal meter (2005). There is another one for the unit with the thin vertical meter (2005A).  From my experience let it warm up at least an hour before calibration. If you have not had it on much since you bought it I would let it burn in a couple of days straight before calibration. FWIW

Regards, robrenz
I think I have the same unit, the meter is the large horizontal one. I did a "burn in" after I received the unit and then I tested the stability by dialing in 10.000 V (9.993 + vernier) measured with a Rigol DM3061 6½ digit DMM. After several days the drift was about 30 µV, amazing! Now I haven't used the PSU in some time, but the dial and vernier is untouched since last time. So, I just powered it on again, connected to the same DMM and I will check on it in a few hours!

I use a cheep 230-115 VAC 50 watt transformer by the way. When I measure the internals of the 2005 and the output voltage, the 2005 is slightly underpowered (95-105 VAC depending on load), but the small wal-wart type 230-115 transformer seems not to get too hot and the 2005 works really well.

For some reason, all the neon bulb was burned so I have them replaced. Always have exotic spare parts! :) (No, they where of course not an exact match. I needed lots of shrink tubing to make them fit in the old holders.)

Edit: When I think of it, I did a 0V calibration, but not the 20V one. Some rainy day... But I really wish I could come up with something to make it a really stable current source without external components/electronics. Maybe replace the current shunt resistor?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 24, 2012, 12:43:43 pm
Have you tested the Rigol with a shorting bar for its DCV stability over the same time period?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 24, 2012, 12:50:12 pm
Have you tested the Rigol with a shorting bar for its DCV stability over the same time period?
No, I have not. I thought about that too, I basically measure the differential drift in two independent instrument so there is a source for error. However, when I measure things like this, the Rigol is only my "readout instrument". In parallell I usually have my Fluke 45 (100 000 counts) and my TTI 1906 "Computing Multimeter" (210 000 counts) to track. They are all within a few counts on the LSD on the Fluke.

But a shorting bar measurement is a good idea! Will do.

Edit: Me and English...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 24, 2012, 03:09:08 pm
This might be the design flaw alm suggested.  In the 2005A schematic if current adjust pot's wiper arm in R35 were to go open circuit briefly, Q10 would not be properly biased.  See photo, Circle RED B + ARROW.  This would alter feedback on current limit section YELLOW CIRCLE, and could blow fuse F2 1A, RED A + ARROW.

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24636;image)

Compare to the much later designed, 2020B, where if the wiper were to open, only the full resistance of R8 or R41 would be felt.

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24638;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24640;image)

The current limit pot was dirty and did go open as you moved it through the range.
Blowing fuses when a pot goes OC for a short time sounds like a design flaw to me. One should always assume that pots might go OC, especially the wire wound ones that might have a single bad turn.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: krivx on May 24, 2012, 03:25:49 pm
I have a 110V PD 2005, and it seems to be in a bit crusty condition.
More to come on this I'm sure...

Dave.

Please give us some notice if you do a video on it - you have a record of affecting the ebay prices of test gear :D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 24, 2012, 03:41:47 pm
Thats a nice post, saturation!

I think I have the model 2005 (without "A", or is it implicit?). The model looks exactly like Paul Rakos: http://www.rako.com/Articles/29.html (http://www.rako.com/Articles/29.html)

And, according to him, the schematics:
(http://www.rako.com/Articles/images/Power_Designs_Model_2005_Schematic.gif)
So, this is yet another alterations of the current control. If I understand correctly, the front panel Adj pot is R25. Funny with the parallel R27 pot. I shall re-read this thread and pay more attention to the current discussion. Thanks for helping, great post!

Edit: Wrong link to schematics.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 24, 2012, 03:45:31 pm
Please give us some notice if you do a video on it - you have a record of affecting the ebay prices of test gear :D

If you are talking about US Ebay you better be looking and buying now. there are not many of the precision units currently listed and even less at sub $100 dollars.  I am partly responsible buying (2) 2020B's (2) 2005's and (1) 2010 in the last several months. They were inexpensive (all 5 totaled $465.00 including shipping) and I could not resist those awesome machined aluminum concentric knobs. :D) There are plenty of the regular power designs supplies listed and they are also very good specs on paper.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 24, 2012, 07:49:24 pm
You're welcome.  The thread hopefully will help other finds faults and fix them, as well as find the value.  There are several variations of the 2005, so check the rear panel for the specific version.  IIRC the younger versions no longer have ovens, for example, then the suffix was added as A, then later B.

The schematic you posted has several of the troublesome pot wiring techniques similar to the 2005B that can cause problems should the pot wiper fail open:

If R25 were to fail, Q8 would not be biased, its similar to the problem of the 2005B current control transistor circuit.

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24652;image)

R27 and 25 are in parallel.  Its a technique for making fine adjustments.  If R27 were to fail the effective resistance would rise to ~< 2x, it should be wired as a modern 3 terminal pot rather than 2. 

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24654;image)

R45 R46 is also of concern, if it opened, it would disconnect the output voltage select rotary switches.  It should be wired as a modern 3 terminal pot rather than 2. 



Thats a nice post, saturation!
I think I have the model 2005 (without "A", or is it implicit?).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 24, 2012, 08:19:45 pm
Any PSU can provide adjustable current sourcing, if they have good voltage sourcing, and have adjustable current limiting.  You can convert any voltage source to current source effectively, as Norton's theorem implies, because neither of them are 'ideal' and thus are different ways of looking at the same phenomena, i.e., duality.

http://en.wikipedia.org/wiki/Dual_%28electronics%29 (http://en.wikipedia.org/wiki/Dual_%28electronics%29)

http://en.wikipedia.org/wiki/Voltage_source#Comparison_between_voltage_and_current_sources (http://en.wikipedia.org/wiki/Voltage_source#Comparison_between_voltage_and_current_sources)

In the case of the precision PD vs regular PDs, you should get very precise and stable current outputs from the precision PDs once the pots are cleaned!  ;D

Edit: When I think of it, I did a 0V calibration, but not the 20V one. Some rainy day... But I really wish I could come up with something to make it a really stable current source without external components/electronics. Maybe replace the current shunt resistor?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 24, 2012, 08:21:33 pm
Same here, looking forward to it.

I have a 110V PD 2005, and it seems to be in a bit crusty condition.
More to come on this I'm sure...

Dave.
Anxiously waiting  ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 24, 2012, 08:21:52 pm
Tank you again, saturation. I did not remember to check the pots when I opened the device. I wonder if they are mis-wired three terminal pots or only rheostats? If the former, a simple wire will improve the safety.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 24, 2012, 08:25:38 pm
Yes, shipping outside the USA can be costly, but consider what the equivalent would have cost to get this much precision and accuracy; even at $200 its still a bargain, its both a PSU and VDC calibrator.

Again you are welcome.  Whether the pots are miswired 3 terminal or just 2 terminal pots, a change in the wiring method would be advised to avoid future problems.  While the fuse will the protect the PD supply, a pot failure may provide uncontrolled current output to any device being supplied by the PD and wired as a current source.

Do I recommend it? Yes. But only if you think its worth the bucks! I payed near $200 for the unit, shipping, customs, Posten's (Swedish postal services) ridiculous fees and have to walk for 1 km to lug it home. The unit in it self only cost me about $70 of the $200 if I remember correctly!  :-\
Tank you again, saturation. I did not remember to check the pots when I opened the device. I wonder if they are mis-wired three terminal pots or only rheostats? If the former, a simple wire will improve the safety.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 24, 2012, 08:35:38 pm
I am running a CC test right now with my 2010 supply. I am running 200mA directly into my 8846A on the 400mA input and giving time for everything to get to thermal equilibrium before I start a statistical test of long term drift.  It still has not reached a stable value yet but the total change (dropping) over 80 minutes is 60uA. (I did turn the air conditioning on  ::)) I am watching on trend plot to see if it levels out at some value before I start.  I am thinking it will be the shunt in the meter and the shunt in the 2010 that need to get to steady state. I am definitely in CC mode with the flashing 0-10V light and have it set for 1V.  I will post what I get as soon as things settle out.

Regards, robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 25, 2012, 01:51:36 am
One of the last <$100 listings currently on US Ebay http://www.ebay.com/itm/Power-Designs-2005-A-Precision-DC-Power-Supply-/300713273173?pt=LH_DefaultDomain_0&hash=item4603e86755 (http://www.ebay.com/itm/Power-Designs-2005-A-Precision-DC-Power-Supply-/300713273173?pt=LH_DefaultDomain_0&hash=item4603e86755) 2 available!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: muvideo on May 25, 2012, 08:51:08 am
I tried to ask the seller if he wants to ship in europe, but ebay doesnt permit to contact him by
any means... maybe he answers no (probably, he lists the items for USA only) but I would have
contacted him directly :(

Fabio.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 25, 2012, 11:43:37 am
Here are the CC results from my 2010.  200mA in current limit directly into the 8846A 400mA input with bnc coax and banana adapters. Set a 1V output.  Meter is in 6.5 digit mode and 100 NPLC.  AC current reading is 9.7uA rms so I think it would be 27.43uA peak to peak ripple assuming sinusoidal waveform.

This photo is the trend plot of the time to roughly thermal stabilize.  The total vertical range is 200uA and the horizontal is 7 hours 58 mins 40 secs. That is a long time to stabilize but I did turn on the air conditioning when I started. But 200uA drift over 8 hours with varying ambient is extremely good in my book. The m on the readings is mA.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24668;image)

This is the beginning of an 8 hour run on stat mode after just 9 readings. started right after the above 8hr stabilize.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24670;image)

These are the results after 8 hours and 16334 readings.  Temperature varied 2.4C with 25.2 max over the 8 hours.
Total min max span is 18.1uA with a SD of 2.658uA. Not bad for an ancient $60 dollar PS.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24672;image)

I will try the same thing on a 2005A next.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 25, 2012, 03:23:55 pm
I cleansed the rotary switch contacts and now it works really well. It's linearity is good but the unit is uncalibrated. But I'm happy. The only problem I have is the current limitation, its not so stable. If I look on the schematics, its probably temp drift in the shunt resistor or the pot, as they are "non ovenized".

MBY,  how unstable is the current? I am seeing about a 1.4mA variation on a 200mA setting on one of my 2005A's on initial testing. (not completely stabilized yet)

Regards, robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 25, 2012, 07:30:33 pm
Wow, I didn't know you could actually see the curve on the bench meter itself,  pics worth 1000s words.  Those are great results too, BTW.

This photo is the trend plot of the time to roughly thermal stabilize.  The total vertical range is 200uA and the horizontal is 7 hours 58 mins 40 secs. ...
I will try the same thing on a 2005A next.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 25, 2012, 07:46:08 pm
Wow, I didn't know you could actually see the curve on the bench meter itself,  pics worth 1000s words.  Those are great results too, BTW.

This photo is the trend plot of the time to roughly thermal stabilize.  The total vertical range is 200uA and the horizontal is 7 hours 58 mins 40 secs. ...
I will try the same thing on a 2005A next.

Possibly a meter-not-a-scope-but-graph-display  :P
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 25, 2012, 11:11:47 pm
I cleansed the rotary switch contacts and now it works really well. It's linearity is good but the unit is uncalibrated. But I'm happy. The only problem I have is the current limitation, its not so stable. If I look on the schematics, its probably temp drift in the shunt resistor or the pot, as they are "non ovenized".

MBY,  how unstable is the current? I am seeing about a 1.4mA variation on a 200mA setting on one of my 2005A's on initial testing. (not completely stabilized yet)

Regards, robrenz
Embarrassedly (is that a word? Firefox says yes but I was never good in English back in school) I do not remember the values, but it was at least as bad as my "Voltcraft" LSP-1403 (a re-branded Manison cheap SMPS PSU), say 10 mA drift in 1 hour or so. My 2005 is in "cool shutdown" at the moment, but I fired the oven up just now. So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).

A couple of days ago, I did run the 2005 for several hours to check the repetivity (again, is that a word? FF says no) of the knob settings (haven't touch them in several weeks), and it returned to 10.0006X VDC after half an hour and the value stayed there (see earlier posts for clarification).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 26, 2012, 03:02:47 am
Wow, I didn't know you could actually see the curve on the bench meter itself,  pics worth 1000s words.  Those are great results too, BTW.

Trend plot is unbelievably usefull, I use it all the time. It is very sophisticated but super easy to use. Press the start button and the rest is fully automatic. Sample rate follows whatever the meter is set for.
Details here https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24730 (https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24730)
After having it I would not buy a bench meter without it.

Details of stats mode here https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24729 (https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24729)

One of the amazing things about this meter is the extreme internal resolution when measuring very small DCV deviations at 100NPLC.  When doing long term stability checks with a shorting bar the resolution in stat mode is 0.2nV  BTW the DCV stability over 152 hours with a 2.6 degC ambient variation is a total min max span of 1.08uV.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 26, 2012, 05:29:39 am
So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).

From what I have seen so far it appears it takes quite a while for the shunts in the meter and PS to thermally stabilize with a given current setting. The trend plot of the 2010 was 8 hours  before it was reasonably stable.  The drift in that time was 200uA. The drift after that was only 18uA.  So it appears that when you are doing current measurements in CC mode (that generate heat in the meter and DUT) it is easy to confuse instrument and DUT thermal stabilization with DUT long term drift.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 26, 2012, 01:58:38 pm
So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).

From what I have seen so far it appears it takes quite a while for the shunts in the meter and PS to thermally stabilize with a given current setting. The trend plot of the 2010 was 8 hours  before it was reasonably stable.  The drift in that time was 200uA. The drift after that was only 18uA.  So it appears that when you are doing current measurements in CC mode (that generate heat in the meter and DUT) it is easy to confuse instrument and DUT thermal stabilization with DUT long term drift.
Yes, there are lot of error sources. What I do now is to feed 200 mA through my DM3061 from another PSU to warm the measure shunt up. And my 2005 is "idling" on a setting of 10.000V with no load. My goal is to see the drift of the 2005 shunt/CC-circuit when "everything" _except_ the CC-circuits is loaded/warmed up.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 26, 2012, 02:06:23 pm
Excellent!  That measurement is more relevant to everyday use than the long term fully stabilized multi day stability.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on May 26, 2012, 04:51:49 pm
what are some practical reasons for a PS this stable?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 26, 2012, 04:57:59 pm
what are some practical reasons for a PS this stable?

Some things that are extremely fussy about 200nV shift ?  ::)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on May 26, 2012, 05:08:03 pm
Driving a couple dozen RTD devices in a plant, or driving an equal number of strain gauges, where you are feeding them all inot a converter, and need the readings to be consistent both with time and between sensors without having to calibrate individually.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 27, 2012, 03:31:48 am
what are some practical reasons for a PS this stable?

Personally I find I gain a deeper understanding of a topic when I attempt to learn all the nuances involved in high levels of precision.  Being a machinist my real appreciation for high precision started when I bought my first electronic indicator with 1 micro inch resolution (38 years ago and I still use it frequently).  My eyes were opened when I could breath on a piece of metal and watch it grow or press on my lathe (which I always assumed to be infinitely rigid) with one finger and watch it deform.  Did I actually need that indicator when I bought it?  No, but the educational value and gut level understanding of how materials behave was invaluable. The same applies for me with electronics. I bought a 6.5 digit 24ppm accuracy bench meter. Do I actually need it? No but I am learning a lot by being able to see things happening that are not apparent with a regular meter.  As with all metrology, knowing what is involved in making accurate measurements at the bleeding edge of precision helps you improve the accuracy of your every day measurements.

These power supplies fascinate me because their old school analog design beats the pants off new high precision supplies. So all my posts here are me just tinkering around and learning by osmosis. Do I have an application that requires a PS with this level of precision?  No but I am learning a lot in the process. :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 27, 2012, 03:45:33 pm
A future of electronic devices is low power, low frequency, running off very small batteries if not alternative energy [ e.g. ultracaps] .  In order to design or troublehsoot such devices you need to be able to provide a clean stable source of 1-3VDC, capable also of bursts of high current, like a NiMH battery:  The PD design can output a stable 2A, 1.250 00 V very nicely.  You can do 1.25 V with most lab grade PSU but you'll have difficulty getting stability in the 10mV ranges, making accuracy difficult with very low voltage transducer outputs that resolve to 1mV, mA or even nV or nA range.

gas sensors: 02, c02, CO
thermocouples
strain gauges
output of biological sources like nerve fibers

emulation of low voltage batteries
kinetic energy sources of power/ charging [ e.g. body motion]
solar cells

http://www.kwjengineering.com/products/carbon-monoxide/sensors-for-carbon-monoxide/3et1co1500 (http://www.kwjengineering.com/products/carbon-monoxide/sensors-for-carbon-monoxide/3et1co1500)

http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?&literatureNumber=slaa207 (http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?&literatureNumber=slaa207)

Before I found that such an ultrastable PSU existed, I used NiMH batteries.  Alas, in the design and test phase you do tend to use up more power than you expect until you tweak it down so as not to use up time charging them back up.

Sensors are expensive, expire, and need gas samples in order to get output.  With the PD supplies, I can emulate the output of many low voltage sensors that is usually done with VDC calibrator source.



what are some practical reasons for a PS this stable?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 27, 2012, 03:57:08 pm
Yes, when you are working with very low power, the set up is very sensitive to ambient conditions, particularly if you are emulating a load with a resistor,  or a shunt.   For sensitive measurements, besides trying to control your climate conditions, I would not shut off the PSU or your DMM and leave them on for the entire period, i.e., days -months, you are anticipate doing testing, even if that just happens to be a few hours a day or a week.  In most metrology labs, such devices are left on perpetually!  FWIW I measured the quiescent draw of the 2020B in the 5W range.  That's $5/yr in energy cost.  My HP3456a draw about 25W each, about $25/yr.


So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).

From what I have seen so far it appears it takes quite a while for the shunts in the meter and PS to thermally stabilize with a given current setting. The trend plot of the 2010 was 8 hours  before it was reasonably stable.  The drift in that time was 200uA. The drift after that was only 18uA.  So it appears that when you are doing current measurements in CC mode (that generate heat in the meter and DUT) it is easy to confuse instrument and DUT thermal stabilization with DUT long term drift.
Yes, there are lot of error sources. What I do now is to feed 200 mA through my DM3061 from another PSU to warm the measure shunt up. And my 2005 is "idling" on a setting of 10.000V with no load. My goal is to see the drift of the 2005 shunt/CC-circuit when "everything" _except_ the CC-circuits is loaded/warmed up.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on May 27, 2012, 04:35:34 pm
I leave my precision reference on for weeks at a time. Majority of the power is in the mains transformer ( about half) and the rest is in the 2 green LED's and the 7815 regulator that provides pre-regulation. The active regulator chip draws very little in operation. For me it is accurate enough to be used as a source of 10.000V for checking multimeters, at least on the 20V range. Other higher ranges with less accuracy, and I take the lower ranges on faith. Resistance I use some 0.1% resistors, and they are fine for the purpose.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 27, 2012, 08:35:57 pm
Excellent!  That measurement is more relevant to everyday use than the long term fully stabilized multi day stability.
Exactly my thought!

Now I have measured and tested for hours, and I have some disturbing results. The CC on my 2005 is performing very poor, much worse than my cheap china PSUs.

Here what I did:
As I said, let my Fluke 45 and my DM3061 measure a current from another PSU to temp stabilize their current shunts. Meanwhile, my 2005 was powered on, dialed in (even max current), but with no load. Therefore, the theory is that every part in the measure setup is warmed to stability except the CC circuits in the 2005. After several hours, my cheap china PSU was delivering minimum of 150.4018 mA and maximum of 150.5309 mA:
Code: [Select]
Max Min Avg Smpl
LSP-1403 150.5309 150.4018 150.4949 17420
PD 2005 147.5291 145.7476 146.1012 100
PD 2005 147.5291 143.3662 144.3162 15970
PD 2005 145.1924 143.3182 144.0457 8820
(Every row with 2005 is a cleared of max-min, to see if things improve after warm up of the CC circuit)
The disturbing part is this: Max and min for the china PSU is drift, while max and min for the 2005 is short time oscillations. Even when I reset the statistics, in a few minutes, the max and min has reestablished.

But, when the CC knob is above the current depending on the load, everything is stable to sub µA and sub mV. So this does not seem to be a noise depending on the load, but on the CC circuits.

I also tried to measure open circuit V, small load V (without CC), with a scope, and even if the drift is very, very small, the noise is huge. I have a peak at 50 and 100 Hz (no surprises there) but the highest peek was at 1.59 kHz. The problem is that I have little or no control of noise-sources as I have my computer near, the scope is a USB one, etc, so the noise can come from everywhere. Anyhow, my 2005 is as good as everyone else's when as a precision voltage source, but my unit is useless as a precision current source. The oscillations does not seem to depend on temperature. Something else is the culprit. 

Sorry for my English, I hope you will understand my tests. Do anybody think that replacing ecaps is a good idea?

Edit: To be clear: All my gear has been on for several days now. The only thing that can be considered "cold" is the current shunt/CC circuits of the 2005. But the PSU has been ovenized and on for the whole time.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 29, 2012, 12:05:14 pm
From what I have seen so far on the 2005A the CC output is much more temperature sensitive than the CV output. My first step will be to replace the current sense resistor (R26 in the 2005A schem.)  that is in the CC control loop with a much lower resistive temp coefficient and higher wattage.  Just holding your hand on top of the PS for a minute will spike the current. The 12 mA droop in this picture is from a gentle blast of compressed air for just a few seconds directed at the top of the PS.

BTW your english is great.  It is infinitely better than my Swedish.

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24881;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 29, 2012, 12:56:57 pm
That's most execellent test, robrenz.  The current limit circuitry doesn't have the same precision passive components so it would be good to see what replacing it with better quality would do to avoid mA swings in current limiting.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 29, 2012, 02:39:18 pm
Wow, I didn't know you could actually see the curve on the bench meter itself,  pics worth 1000s words.  Those are great results too, BTW.

I started a separate thread on Trend plot to show more info and not get OT here. https://www.eevblog.com/forum/projects-designs-and-technical-stuff/trend-plot-on-fluke-884x-meters/msg114826/#msg114826 (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/trend-plot-on-fluke-884x-meters/msg114826/#msg114826)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 30, 2012, 03:31:26 pm
From what I have seen so far on the 2005A the CC output is much more temperature sensitive than the CV output. My first step will be to replace the current sense resistor (R26 in the 2005A schem.)  that is in the CC control loop with a much lower resistive temp coefficient and higher wattage.  Just holding your hand on top of the PS for a minute will spike the current. The 12 mA droop in this picture is from a gentle blast of compressed air for just a few seconds directed at the top of the PS.

BTW your english is great.  It is infinitely better than my Swedish.

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24881)
Thank you! The trend plot is a real killerapp! Something I'm disappointed with regarding the DM3061 is the cheap stat functions. It shows max, min, average and number of samples only. Not even standard deviation, but every cheapish sci-calculator has one!

I have some good precision current shunts at home, maybe I will switch out the shunt in the 2005. But the thing that disturbs me is the "oscillations". The drift is no big deal (after a reset of the stats, the max and min values re-establishes, but the "window" does not seem to move. The oscillations is fast, maybe a couple of minutes. At first I thought it may depend on the oven thermostat, but my feeling is that the oscillations is faster than that. Any ideas?

Another thought: My 2005 may be a little bit underpowered. I'm using a 230->115, 50W transformer and the actual voltage is about 95 with the oven on, 92 VAC when oven on and full output load. But I still don't think the oven/thermostat is to blame for the oscillations since those are faster than the oven on-off cycle. But maybe the low voltage could be a problem anyway?

Speaking of oven on-off-cycle: It would be interesting to hear from others what they clock the cycle to, just for comparison? I haven't did that myself, but give me a few days and I will. (Amb temp + on/off duty and frequency after several hours)
The thermostat is presumably a bi-metal of some sort, as it gives a distinct sound. Have anybody played with the thought of replacing that with a PID control? I'm a little bit concerned with contact wear out.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 30, 2012, 04:19:43 pm
The resistance temperature coefficient is much more important than the precision of the resistor in this case. So make sure you know what those shunt tempco's are. I have looked and at low ohms and 3W it is hard to find anything with a tempco lower than 50 or 25ppm. I see those slow oscillations in CC also.  They are there in CV mode also but are very small.

I am pretty busy with work right now so I wont be participating much for the next week or two but I will be back.

Trend plots of oscillations when supply is set for 10uV.  That is 1.2886uV PP oscillation with spec. of 100uV PP  we are splitting hairs here but I do wonder what causes the slow oscillation.  The choppy plot may be aliasing from the low sample rate of the Trend plot.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24927;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24929;image)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24931;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on May 30, 2012, 05:43:08 pm
Having a hard time ... deciding whether the fluke meter is a multimeter or a very slow scope  :-X
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 30, 2012, 06:40:24 pm
Its like a scope's roll mode.  Several DMM that have trend capture have similar functions.

(http://www.fluke.com/images/Products/Digital_Multimeters/289_200p.jpg)



Its
Having a hard time ... deciding whether the fluke meter is a multimeter or a very slow scope  :-X
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 30, 2012, 06:47:04 pm
Again, very nice data.  High precision resistors tend to have good tempcos, but not necessarily as high as you'd like.  Alas, to get it nearer to nil you'd have to mix a + and - tempco to null each other or match them so that if its used as a divider the ratio remains stable over temp.  A simple way to do it was posted here:

http://conradhoffman.com/MML%20files/1_vref_p3.jpg (http://conradhoffman.com/MML%20files/1_vref_p3.jpg) 



The resistance temperature coefficient is much more important than the precision of the resistor in this case. So make sure you know what those shunt tempco's are. I have looked and at low ohms and 3W it is hard to find anything with a tempco lower than 50 or 25ppm. I see those slow oscillations in CC also.  They are there in CV mode also but are very small.

I am pretty busy with work right now so I wont be participating much for the next wee
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on May 30, 2012, 07:59:31 pm
The resistance temperature coefficient is much more important than the precision of the resistor in this case. So make sure you know what those shunt tempco's are. I have looked and at low ohms and 3W it is hard to find anything with a tempco lower than 50 or 25ppm. I see those slow oscillations in CC also.  They are there in CV mode also but are very small.

I am pretty busy with work right now so I wont be participating much for the next week or two but I will be back.

Trend plots of oscillations when supply is set for 10uV.  That is 1.2886uV PP oscillation with spec. of 100uV PP  we are splitting hairs here but I do wonder what causes the slow oscillation.  The choppy plot may be aliasing from the low sample rate of the Trend plot.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24927)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24929)

(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=24931)
Yes, I was a little sloppy to call them "precision shunts" without pointing it out that I actually meant the tempco. I have an assortment with shunt resistors in 1, 2, 3 and 5 watts with incredible low tempco's. I think one of them actually is something like 2 or 5 ppm, but most are 10, 25 and 50 ppm. If and when I try to use them I will give the part numbers if I can. (Edit: The best I can find in the "low tempco"-resistor bin at the moment is 25 ppm (5W and 22 Ohm, way to high). Hmm, I'm sure that I have better ones somewhere...)

May I ask what time you have on the X-axis on the trend plot? I missed that. Thank you again for a great post! I feel a little relieved that you see the oscillations, they where not just in my head! :)

I my girlfriend allows it, I may do some more testing in the weekend! ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 30, 2012, 08:39:04 pm
May I ask what time you have on the X-axis on the trend plot?

The number between the min and max is the time of the last plotted point. So you can interpolate what the x axis is per division. In this case showing minutes and seconds. It will add days also when it gets that far.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 01:07:31 pm
Ok, that gives about a 30-40 second oscillation period. I shall try to verify this in the weekend.

Now I have started up another experiment to measure the duty cycle and period of the oven. A CdS is attached to the oven lamp and my Fluke 45 is logging via RS232 to a computer. The 2005 was in "cool shutdown" for a couple of days, so I going to capture both the initial warm up cycle and the "steady state cycle" in a few hours (or a day or so I expect).

Then we can superimpose the oven cycle with the output oscillations and see if they are independent or somehow connected.

It's very interesting that you noticed a oscillation even in the CV mode. What was the load? If the load was very small or none, that almost rule out the CC circuit or shunt to have anything to do with the oscillations.

Three ideas:
1) The oven cycle interacts
2) Other thermal oscillations due to unknown factor
3) Large RC-constant somewhere in the design (maybe in some discrete amplifier circuit since the ironic rule "if you build an amplifier, then its a oscillator, if it amplifies, then you tried to build a oscillator")
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 01:10:07 pm
Oh! No! Nooo! Nooooooo! Magic smoke from the 2005!!!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 01, 2012, 02:06:39 pm
Sorry to hear that.  but it will add some diagnostic input to the thread ;D
I have done some more testing with the Trend plot using a function gen to understand the sampling times. I have been using 100 NPLC on my testing but now realize that is a 0.573Hz sampling rate which is definetely aliasing on the waveforms I posted. When I am able I will post more info on the Trend plot Thread https://www.eevblog.com/forum/projects-designs-and-technical-stuff/trend-plot-on-fluke-884x-meters/msg114826/#msg114826 (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/trend-plot-on-fluke-884x-meters/msg114826/#msg114826)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 02:42:32 pm
Ok, what now then? The crash scene investigation has only begun, but I will need some help here I think.

The oven got really, really hot and started to give off fumes. Nothing outside of the oven seems damaged except C14 mounted on the oven assembly socket. I used huge amounts of freeze spray, but the oven kept getting warm again (unit unplugged, of course), so the hot part was deep inside and since the thermal conduction is poor, the freeze spray had little effect. I pray that the inner workings is intact but you never know. Now its cool and I started to disassemble the oven.  The outer red colored tube comes off very easy, fitted with three screws. Underneath it, is two layers of two different kinds of thermal insulation. One of them is glass wool, the other I don't know, but when I unrolled it I instantly recognized it as the heater. Its a heating filament. Underneath it, is another steel tube housing the electronics and probably the thermostat.

The heater filament measured about 1.6 kOhms (cold resistance) and the filament was lying directly on the well-conducting steel tube. My initial guess is that a short circuit in the filament<>steel tube made the current increase as well as locking up the thermostat.

I noticed, when I was freeze-spraying that the assembly clicked. After a few second of not spraying, another click. And so on for a couple of times. That was probably the thermostat cooling down below threshold, then warming up again due to thermal inertia.

What I will do now:
The filament isolation is not to be trusted, so I took away the wire. I will try to run the 2005 without heater to get a feeling if other parts are working or the electronics inside is burned. Its probably hard to get inside the inner steel tube, as it seems to be riveted (small, small, rivets) to the base.

What I need help with:
Cold resistance between pin 10 and pin 9 on the oven (if someone could please do this measurement with one of the pins desoldered [not to measure the trafo wiring or other error sources]) and thermistor cold resistance [likely to be near 0 ohm of course, but I want to be sure] I would be very grateful!

I someone could measure the temperature of the oven (by demounting the outer shield and then stick a thermocouple inside the end cap of the inner tube) I would again be very, very grateful! I want to assess if the thermostat is working or not. I tried to trigger the thermostat with my heat gun, but the two complications is this: 1) I have no idea of the proper running temp, and I don't want to overheat the assembly again, and 2) I have no good idea of where the thermostat is. Presumably inside the steel tube, but maybe in the base.

Stay tuned for pictures...

Edit: "off course", not "of cause". Edit2: NO! "of course". I will never learn English, thats for sure!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 03:19:00 pm
An intriguing and maybe important find: As I was by sheer luck measuring a CdS resistor "connected" to the oven lamp for duty cycle measurement I discovered that the oven lamp probably started to shine more bright a few minutes before I was smelling the smoke. The resistance for the CdS went down from 90 k to 30 k instantly. Edit: It was warming up, so that the oven did turn on was NOT the case. No oven lamp-resistance was 250 kOhm.

That is very strange as it only can be explained by a open (or increased resistance) heater filament or a overvoltage situation. I have measured the cheapish 50W 230->115 VAC transformer and its output is normal (111 VAC, no load). The filament was not open, it measured 1.6 kOhm. The only other thing is a short in C14 in combination with a thermostat resistance significant higher than 0, or a thermostat short circuit, again with a nominal resistance of significance. The C14 measures normally (though badly burned), 9.9 nF, no short circuit and a thermostat of higher resistance in the "on" state seems implausible. 

(I will be back with pictures and schematics to make the text a little less confusing)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 07:30:16 pm
Ok, here comes the pictures!

Edit: Comments:
C14_burned.jpg: The C14 cap is mounted on the oven leads. Its surface is burned but it measures correctly after desoldering. Apparently all the heat was transfered via the leads to the cap. Strange.

Thermal_isolation_and_heater_filament.jpg: This was the stuff under the red shield, between the shield and inner steel tube. Its glass wool (I think) and some isolation around the filament. The filament is the fine wire.

Inner_tube_with_filament_tracks.jpg: This is the inner tube. You can see "tracks" of the filament that was winded around the steel tube. The filament thread is isolated with something that today only is like a powder. I hope its not asbestos!

oven_assembly_inner_tube_end_cap_removed.jpg: The inner tube has an end cap removed and not shown. This is the view of the "core" PCB with all the critical components. I sure hope its okay, otherwise the 2005 is dead!

oven_overview.jpg: A overview of the oven. The red can to the right is the outer shield.

oven_scematics.jpg: Schematic of the oven heater. Excerpt from the original schematics. As you can see, its seems drawed by a confused retard.

Oven_kicad_schematics.jpg: My KiCad redraw of the oven heater. Hopefully a bit easier to understand. I also hope that I drawn it correctly. Edit: Stupid me! The neon bulb is of course NOT in the oven, but on the front panel! Don't mind the bulb placement in the schematics (inside the blue rectangle).

2005_duty_BatteryLog_disaster.JPG: This is the measurement of the CdS (light dependent resistor). My software was originally created for battery measurement, therefore the strange name of the picture. This has nothing to do with batteries!

Power_Designs_Model_2005_Schematic.gif: As reference, the entire original schematics and component placement.

Please help! Any input is appreciated!  My only idea so far is to run the 2005 "cold" to check if the electronics work, but I'm reluctant to plug it in!

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 01, 2012, 09:39:34 pm
Ok, I could not restrain myself from running the unit without heater. I have put one thermocouple inside the "core" of the oven assembly and one in the mains transformer, just to measure if something seems to be overheating.

So far so good, the dial is still on 9.993 V and output is 10.005 V, but of course with "huge" drift.

So, I think the electronics has survived! Yeah!!!!!

But something that is bleeding obvious is another oscillation! The freaking oven lamp is pulsating in a sawtooth manner in a period of 3 seconds! A notable dim down, then slowly rising in brightness, and then a sudden dim down again! I think I'm on to something. You see, a neon bulb is actually a active component. Sort of. Its possible to create multivibrators, logic gates and flip flops using nothing but neon bulbs, resistors and caps. Its an old dying art and I'm far to young to be an expert, but I know it could be done and I have done experiments myself. A "bulbe astabile multivibrator" is actually pretty trivial.

So, here what I think: The bulbs is creating the oscillations for some reason. There may be unintended bulbe oscillators! It is however very strange since all bulbs except the "+10V" one is driven by AC. You should have to have DC to make oscillators. What the heck is going on?

As I have no ovenized 2005 right now, but a crippled one I cannot confirm the drift-oscillations at the moment as the temp drift masks things out, but if someone is to temporary cut a wire to one or all bulbs I bet that the drift improves!

Here is a whole book on neon lamp circuits:
http://computer-refuge.org/classiccmp/neon_lamp_logic/ (http://computer-refuge.org/classiccmp/neon_lamp_logic/)

Edit: Another non obvious component is RT1, a disk thermistor mounted on the main PCB, well outside of the oven. NTC? PTC? The BOM doesn't say anything but 1000 ohms at 25 C. Its mounted as if it where to monitor Q4, but why? I have to spend the whole freaking night looking for "relaxation oscillators" in the vintage style, non obvious schematics...

Edit: English...

Edit: Hmm, the visible oven lamp oscillations has stopped! I dared to freeze-spray the bulb, the inner tube of the not-so-warm oven and on some random places, but the oscillations did not re-appear. Spooky shit!

And... As I was typing, the oscillations re-appeared when I toggled the ON switch! But they are much fainter now. What is this shit? A psychological phenomena? I'm seeing stuff? Confirmation bias? I getting mad! I don't even know if I should fix this with a solder iron or a shrink! :P
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on June 02, 2012, 05:43:49 am
It could be C14 has become conductive, and is acting as a varistor. Best tested by replacement, as it is a very elderly ceramic, and they are known to grow whiskers internally like any other ceramic capacitor.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 02, 2012, 11:49:12 am
I tested C14 with my UT 511 isolation tester. I tested up to 500 VDC in both directions and found no problem. As I said before I also tested it for capacitance and measured 9.9 nF, so it seems to be okay (but I will replace it anyway).

And an intermittent short would only force the oven on, not increase brightness on the oven lamp and badly overheat the oven in such short time, if not the thermostat has a significant high resistance. I found the latter to be implausible as it heat up itself.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 04, 2012, 11:06:20 am
I still don't know what went wrong. But as the electronics seems to work fine, only the oven needs replacement. I have started to design a new heater, but I have no good numbers on the original one.

Using a power meter in the wall socket before, I noticed that the oven consumes about 10 watt in power. But there is likely to be losses from the 230->115 VAC converter included. I also have no good idea of the ballpark temperature is to be, eg when the thermostat trigger. It should be fairly easy to measure the heater filament resistance and the regulated temperature on a functionally sound unit without the need to take it apart in atoms. The outer red shield comes off pretty easy and the end cap of the inner steel tube is also easy to remove. To measure filament resistance, one leg of the oven needs to be desoldered.

If someone where to measure the temperature and/or the filament resistance on their unit I will be very grateful! Especially the temperature would be very useful for me. My goal is to regulate at a slightly lower temperature not to trig the thermostat if it perhaps works. A lower temperature controlled by PID and a recalibration should make the unit almost new! :)

I'm starting a new thread on the oven project, stay tuned...

Edit: Link to the project thread: https://www.eevblog.com/forum/projects-designs-and-technical-stuff/a-new-improved-oven-for-the-pd-2005-precision-power-supply/ (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/a-new-improved-oven-for-the-pd-2005-precision-power-supply/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: andyb on June 14, 2012, 04:11:01 am
Just wanted to let you guys know that this thread compelled me to buy a PD 2005 and register for this forum...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on June 14, 2012, 06:33:27 pm
Welcome, when you've a moment, give a review for us.  Since they are all used, the end-user quality can vary, but so far its been fairly tough.


Just wanted to let you guys know that this thread compelled me to buy a PD 2005 and register for this forum...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 21, 2012, 09:41:48 pm
I'm doing some progress with my new heater. The PID regulates well, but is (I imagine) too slow when put in real service. A bigger temp change takes some time to adjust and as it happens, the electronics inside the heater (the reference amp stuff) contribute to the heat. So, when the PSU is off but the oven is on I imagine that turn on will rise the temperature, adding time to stabilize. That somewhat defeats the purpose of having the oven run on all time. I'm sure I can figure it out somehow.

Anyway, I plead to you who owns a PD2005 to help me! I really could use two key facts.
1) What is the running temp inside the oven with the thermostat drive?
2) What is the power of the heater?

These two key facts is really easy to measure. The first one only need a screwdriver.

1) The outer (red) shield is held in place by three screws in the socket. They don't need to be removed, only loosened. Then, the shield will come off if you turn it slightly and then it just separates. Inside, you will find a inner tube covered with isolation, but with a end cap that is not covered. The end cap comes off with two screws. Then you can stick a common thermocouple or whatever inside the electronics package ant measure the temperature. I'm not proposing anything destructive here! You can reassemble the end cap and the shield as easy as it comes off! I'm not suggesting that you should break or harm your 2005 for me!

2) The second does even not need dismantling anything besides removing the cover of the unit! Do like this:
A) Turn off the device (front panel switch. This is to break the transformer from the heater).
B) Disconnect the unit from mains (not only for safety, but also because you otherwise will try to measure ohms of a live wire).
C) Measure resistance between pin 9 and pin 10 on the heater assembly socket (clearly marked on the socket)
D) Measure resistance of the thermostat (in "on" position presumably), between pin 11 and 9.
There are some caps in parallel with the heater and thermostat so please measure "common" ohms on a simple multimeter, not a real LCR meter doing AC measurements. 

Its easy! A temperature and two resistances. It will not break your unit (if you aren't incredible clumsy)!

First one that comes up with those digits will be mentioned on the PCB of my second spin of my new PID regulator! :)
...make that the two first. One brave first, and one for confirmation! :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 26, 2012, 11:41:35 am
Pin 9-10  674.3 Ohm
Pin 9-11  .00839 Ohm
Oven case temperature 48.0 Deg.C

I did not want to open my oven and since the absolute temperature is not critical I feel the temp of the top of the oven with a thermocouple is sufficient. It was measured with the outer case on so it should be very close to the inner temp anyhow.

robrenz
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 26, 2012, 03:17:35 pm
Thank you robrenz! 674 ohms is much lesser than I expected. That translates to over 19 watts of heating power. Did you measure with the unit unplugged and in off-mode (otherwise you will measure the transformers primary in parallel)?

I think it is a difference between oven shield and inner temperatures. The insulation was wired around the inner heater and on the top, so isolated in all directions. I think the best spot for external temp measurements is perhaps the base as there is no room for isolation (an air or plastic gap maybe).

As you said, the absolute temperature is not critical, its only a matter of calibration. I have done the first tests of the oven controller heating the real electronics. My setpoint is 60 degrees. I shall do experiments with insulation as I don't plan to re-use the old isolation (some wool). I actually did experiment with toilet paper but I think I go with something else. I'm experimenting with a shield in alu foil and maybe I get a chepo vacuum flask.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 26, 2012, 03:20:13 pm
Thank you robrenz! 674 ohms is much lesser than I expected. That translates to over 19 watts of heating power. Did you measure with the unit unplugged and in off-mode (otherwise you will measure the transformers primary in parallel)?

Yes unplugged and off. :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on June 26, 2012, 03:34:48 pm
If you keep under 50C then polystyrene will work as an insulator quite well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on June 26, 2012, 07:32:09 pm
Thank you robrenz! 674 ohms is much lesser than I expected. That translates to over 19 watts of heating power. Did you measure with the unit unplugged and in off-mode (otherwise you will measure the transformers primary in parallel)?

Yes unplugged and off. :)
Hmm, that may explain why the heating up period of my PID is so slow as I only putting in about 5.5 watts to the heater. I used Kanthal wire of 178 ohms/m (six sub-metre threads in parallel making 21 ohms totally). My setpoint is 60C, and I think I will settle there as I suspect that the original temperature is higher. Lower temp translates to longer working life and lesser power consumption (in the heater, not electronics of course) but may be more sensitive to ambient temp drift.

SeanB: Thank you for the tip. I may settle at so low as 50C, but if I find a good insulation for higher temp I will try to use a higher setpoint.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on June 26, 2012, 07:49:09 pm
The original would be a simple glass wool, a rather nasty thing to work with. Causes skin problems, and the fibres are known to be carcinogens. Try using some polyester wool as a replacement, the common wall insulating ones will work well up to about 50C with little problems. Not good if you are running at more though, it likely will melt.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on July 01, 2012, 12:13:50 pm
Pin 9-10  674.3 Ohm
Pin 9-11  .00839 Ohm
Oven case temperature 48.0 Deg.C
I'm doing a second spin of the board now (pics and description in the other thread for the project). I promised to add something (copper layer, as this is home-etched) to thank you for your help. Some ideas?

The original would be a simple glass wool, a rather nasty thing to work with. Causes skin problems, and the fibres are known to be carcinogens. Try using some polyester wool as a replacement, the common wall insulating ones will work well up to about 50C with little problems. Not good if you are running at more though, it likely will melt.
Yes, it's was glass wool outside the filament and some pulverized stuff that has the same grey-blue color as asbestos just around/under the filament. A got rid of it all and is currently experimenting with insulations. Toilet paper, PU foam, cotton pads and even a vacuum flask are among those things I'm testing with. I'm actually going to fit some stuff outside of the outer shield as well. It's gonna be overkill! :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Aldobrandi on September 04, 2012, 09:14:29 pm
So after thoroughly reading this thread and lusting after the stability of these supplies I decided to get myself a 2020B for my hobby work (got it for $80 plus shipping). After some very basic testing the unit seems to be in good working order and its insides are pristine looking (ill try to upload pics later). Now it was last calibrated in 1999 and i lack the equipment, let alone the skill, to properly calibrate it. I contacted a calibration lab here in NJ and they told me they'd charge me $75. Does that sound fair? Also what kind of tests can you recommend I do with my pathetic equipment (4000 counts Chinese DMM) and no oscilloscope (yet!) before I send it?

Thanks a lot in advance and a huge thanks for bringing these puppies to my attention!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on September 04, 2012, 09:48:34 pm
Roughly check the voltage drift from set after letting it stabilize for half an hour, then probe the outputs for any noise if exist means caps expired
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on September 05, 2012, 01:14:22 am
Also what kind of tests can you recommend I do with my pathetic equipment (4000 counts Chinese DMM) and no oscilloscope (yet!) before I send it?

I have 5 of these and I have checked and calibrated them with my In cal 6.5 digit 24ppm meter.
My suggestions after my experience with them:
Don't have it calibrated unless you have a darn good reason , It is probably more accurate as is, than your meter. 
Don't worry about ripple,  its rated at 100 microvolt P-P, unless you have a very good differential probe setup and a scope with 500 microV per div you are not going to be able to measure it. You are going to see all kind of noise instead.
Do invest in some Caig de-oxit and thoroughly clean the rotary switch contacts.  They will give a lot of error if not in good condition.
The calibration is very easy and just requires a accurate meter. 
Save your money for a more accurate meter and then calibrate it yourself.

PS,  Forget about drift after warmup. Unless you have a darn good bench meter your meter is going to drift more than this supply.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Aldobrandi on September 05, 2012, 02:30:13 am
Thanks a lot T4P and robrenz for your suggestions. I did run for a few hours and was not able to measure any drift what so ever. I think time has come to complete my lab with a decent meter and a scope. I am so excited about this supply, I had a good hour and a half of looking at it under all possible angles, the construction is superb.

Also on a side note, do you recommend that I purchase a new meter in the $100-$200 range, or should I buy something better on ebay but then take the risk that it won't be calibrated either ? I am sure I can find used and calibrated 87-III but are these worth the $100-$150 they usually go for or should I spend a little more for an 87-V ?

Thanks again and sorry for momentarily hijacking the thread with my DMM question!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on September 05, 2012, 03:27:23 am
This is a do as I say, not as I do moment. :-[  Don't get caught up in high precision until you need it or you can buy it realy cheap. Get a decent scope and start building things.  Then buy things you actually find yourself in need of.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Aldobrandi on September 05, 2012, 03:44:34 am
Got it, thanks for the kind warning  :D I know this is a slippery slope and watching your amazing videos believe me I'm this close to buying a microohm meter or a 6.5 bench meter. Haha but I'll be reasonable. Thanks again!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: T4P on September 05, 2012, 03:50:46 am
You can try out a Rigol DM3068, very versatile that thing

As for handhelds i assume you would take a look outside of flukes right?
For a start, the Agilent U1252B and the Sanwa PC7000 ( also known as the Brymen BM867 ) or if you do not want to spend that much well look at a Mastech MS8218 or an UT61E
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Aldobrandi on September 05, 2012, 06:54:48 pm
I'm definitely open to any good meter. I guess I have the Fluke reflex like many but I have been eyeing the Agilents for a bit of time now and although I don't think I'm ready to spend the money for the U1252B I think it's gonna be a showdown between the U1272A (love the data logging capacities and the other nice features like the Auto Hold) or more likely the more humble U1242B. Once again I really appreciate the suggestions!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: linux-works on September 19, 2012, 04:13:11 pm
I can't seem to resist this style of psu.  just bought my 4th one, this week (the 5020):

(http://farm9.staticflickr.com/8037/7998314828_cdce34f634_b.jpg)

the others are 2020, 2005 and 2010.  one is oven based and the rest are lm399 (I'm guessing) based.

the 5020 was a deal at $100.  could not say no ;)

a friend asked me why I need so many.  and I don't -need- so many.  I just wanted them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on September 19, 2012, 06:24:37 pm
NICE!  They are magnificent supplies, when I got the bug I got 3 in a short time span.  Enjoy them.  They photos look like they are in very good shape.  Did you have any problems with the fine adjust knob as myself and robrenz had?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: linux-works on September 23, 2012, 11:42:51 pm
I have not read the whole thread; what problems with the knob are there?  which model?

they all came pretty dirty and I spent a good 1-2 hours on each one, fully breaking it down and cleaning as much of it as I could.  the 2005 is the oldest and I replaced all the electros inside.  the others I have not gotton to, other than to use deoxit on the contacts.

the top one (5020) is still quite dirty as I have not even taken any cleaners to it or even removed the top cover yet.

once I deox'd the contacts, I saw accurate steps on the click knobs.  amazing that that, alone, seems to get 95% of the job done (or more).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on September 24, 2012, 12:07:46 am
Any, but you recognized the disease and have the treatment already, deoxit, it will get 98% of the issues, the next 1% is recalibrating the dials by turning the adjust screws correctly and the last 1% is cleaning the chassis  :D!  We've had dirt on the fine adjust pots, all it needs too is dexoit.  So we have all had the same issues. 

I have not read the whole thread; what problems with the knob are there?  which model?...

once I deox'd the contacts, I saw accurate steps on the click knobs.  amazing that that, alone, seems to get 95% of the job done (or more).

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on September 26, 2012, 05:45:47 pm
I suggest compressed air first if you have it to remove all dust that will blow off. Then a thourough wash with a general electronic cleaner to get the general gunk off the switch assemblies and the detents.  The detents will probably have caked old grease in the ball pockets. Then apply deoxit D100L to all the contact fingers and thoroughly cycle the switches. Re lube all the places where the switch shaft engages other parts and grease the detent assemblies. I personally like wash the D100L off and then lubricate with Deoxit G100L.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 12, 2012, 07:00:42 pm
Just a bump with a quick test for output ripple.  i got a Preamble 1855 differential amplifier from fleabay and thought I would give it a quick try on the output ripple on a PD 2010.  This was more to see if the diff amp would let me actually see the ripple without all the ambient noise. I was testing at 3mV unloaded.  The precision offset voltage generator in the 1855 allows DC coupling while measuring the ripple.

8846A AC reading at 10NPLC and 200Hz filter. Secondary reading is the DC component. Darn, I am going to have to recalibrate the 2010 its 0.4 uV off  ::)  12.7uV RMS = 36uV PP according to the 8846A.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=31506;image)

Both pictures below are this setup: 1855 setup with dc coupling, 10X gain, 100kHZ BW limit, 1M input resistance, 3mV differential offset, 1x probes. Tek 2225 setup with DC coupling 500uV/div, 0.1uS/div, PP auto trigger, LF reject.  This gives 50uV/div on the scope display.

This shot is with the two probe hooks connected and the two standard ground leads clipped to each other.  I would consider that a clean 50uV noise floor.
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=31508;image)

This shot is both probe hooks removed and the probe tips on the output of the PD 2010.  If you visually subtract out the 50uV noise floor I would say it is below the 100uV PP ripple spec.  I know, not very scientific, like I said I wanted to try the diff amp.  ;D
(https://www.eevblog.com/forum/product-reviews-photos-and-discussion/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=31510;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on October 12, 2012, 07:57:20 pm
That's wonderful robrenz, I don't have a probe to get that much resolution, so its good to see it.  They clearly don't make them like they used too!

For readers interested, quite a bit of these precision PSU pop up on eBay weekly. 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: miciotta on October 15, 2012, 05:48:01 pm

hi to all....

sorry but you that are a expert, i am beginner...

what power supply regolable at nice price i can buy ?

i see the  PeakTech 6140  0-30 volt  0-5 ampere is good ?

or for 80 - 120 euro what i can buy  ? LINEAR not switching ?


thank...... kiss from mery
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on October 22, 2012, 08:37:59 pm
I'm unsure about which thread to post in, but my replacement oven project is coming around (see this thread (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/a-new-improved-oven-for-the-pd-2005-precision-power-supply/msg155620/#msg155620) about that project) and I'm back to benching the PD2005. Therefore, I post in this thread now.

Anyhow, when the temperature is regulated well within one degree C, I'm a little bit disappointed about the stability. With a setting of 9.986 (uncalibrated) I get as close to 10.000 V as I can, I logged the stability for a few hours and get a drift (up and down, up and down, haven't established the cycle period yet) of 140 µV. While not terrible, I think its almost an order of magnitude more than I hoped for. Coincidentally, I think my thermal regulation is about one order of magnitude better than the old thermostat control (I experimented and found it to have a off-transition at 70 degrees C and an on-transitions at 65 degrees), about 0.5 degrees C instead of 5 degrees. (Actually, my external thermometer with its K-sensor bonded together with the NTCs I'm using to control things indicates even better control, better than the resolution of the thermometer of 0.1 degrees, but I know that the PD2005's electronics itself generating some non-negligible heat, creating hot spots).

Interestingly, the stability seems to be improved by a higher set point. Thats not terribly surprising though, but I did not expect a steep improvement. More to come, I'm have to do some more exhaustive tests and take notes. Now its much "gut-feeling", and that is not very scientific... :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 25, 2012, 03:38:40 pm
Found this just looking around and they shows many power designs parts as available.  Looks like the kind of place that will charge 10X the reasonable price.  I don't need any parts at the moment, just thought it might help someone.

http://www.justnsnparts.com/manufacturer/power-designs-inc.aspx (http://www.justnsnparts.com/manufacturer/power-designs-inc.aspx)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MBY on December 02, 2012, 06:34:20 pm
Now I have done further tests. The oscillations of the output in CC mode is not due to the oven thermostat as I still see the oscillations of the same duration and amplitude as before. One other thing I have noticed is that the CC circuit is really slow. I haven't noticed it before since the DMMs have a certain update speed. But checking on a scope it becomes clear that the rise time from CC mode to CV mode is very slow, in the order of hundreds of ms. But not always, its hard to reproduce. Easiest seen on high current outputs, like 0.4-0.5 A.

I think this is connected to the oscillations but I don't know how. It may be the input fluctuating somehow and the CC circuits slow response causing it.

Quite annoying. The CC stability is only a few mA (well, thats quite good, but I expected better), the CV stability is at my current oven settings about 10 µV.

Edit: Some data:
Setting 10.000V, CC=500mA
Rise time (disconnect of a 6.8R resistor): > 250 mS to 90%, >500 mS to 10.000V
Fall time (reconnect 6.8R):  25 mS to stable output.

Those figures are actually piss-poor! Well, the unit is not designed as a fast CC limiter, but this slowness affects the total stability of the CC mode, I'm sure!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 06, 2012, 07:47:55 pm
This post/thread (https://www.eevblog.com/forum/reviews/power-designs-tw-4005-teardown/msg169094/#msg169094) gave a good opportunity to try out my $35.00 high performance differential amplifier on power supply ripple. For continuity I am posting it here. Yes it is a little bulky and takes up quite a bit of space but the performance is eye watering. OK I had to buy a $150.00 scope to plug it into also so it really cost $185.00 But these scopes have a signal out on the back so this whole setup can really be a high performance differential preamp that feeds a digital scope. :-+

Tek 7603 scope with 7A22 differential amp in the middle hooked to a PD 2005A with 2 bnc to banana cables. The banana cables were less noisy than 1X probes even with a direct probe tip to probe tip adapter that also couples the probe grounds right at the tip.
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34101;image)

$35.00 Tek 7A22 differential amp 10µV/div 100000:1 CMRR. Separate upper and lower cutoff filters DC offset capability 1MHz max.BW AC coupled in this case.
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34115;image)

PS hookup with 10 ohm resistor and set at 1V.  Cable grounds connected to each other and the PS ground. Red leads are the differential signal leads
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34117;image)

Noise floor @ 10µV/div, inputs grounded internally, maybe 5µVpp.    Analog beauty :P
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34107;image)

Noise floor @ 10µV/div, cables connected as shown in PS picture above except the two red signal leads are plugged into each other only to see noise floor of setup.
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34109;image)

Lower filter is dc upper filter is 3 kHz I would call that a clean 40µVpp ripple. PD 2005A spec is <100µVpp  This is one complete cycle of a repeating pattern not just what I happened to trigger on. It is also line frequency based since ac triggering on line gave a solid trigger. Also the period is .0166 seconds = 60Hz
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34111;image)

Lower filter is dc upper filter is 300 kHz.  With higher frequencies added I would still call this a easy 60µVpp ripple without even subtracting out the baseline setup noise/ripple of 10µVpp
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34113;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on December 09, 2012, 04:28:44 pm
10uV/div?  :-+ :-+ :-+ :-+ :-+ :scared:

I guess I know what my next purchase will be.  This a great amp for DC measurements, with some AC on it.  I need to get a differential amp like that!  Low cost differential probes from Testec, or Tie Pie [ BTW they seem to be the OEM for many folks like Yokogawa or old Lecroy] have noise rated in the 100s of uV and can't begin to measure the PD noise floor, and yes the probes alone used cost more than your whole setup!

The most I've done is connect it to my 3456a, and estimate DC variation vs when the meter is shorted, to remove the LSD drift.  For AC all I can muster is using the 3456a AC mode to measure the ripple as RMS. :palm:

That is one kick ass microvolt input scope!  Few can match it today, most top scopes do 500uV/div as minimum, if at all.  Not to mention the dynamic range, 10uV to 10V /div, it took a while to look at that range before I realized it was true!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alm on December 09, 2012, 06:14:35 pm
This has come up before, for example when Dave was so impressed by the Tek 2225 that went down to 500 uV/div.

The modern equivalent would be the Tek ADA400(A), which requires a TekScope interface (power pins around the BNC connectors) or $$$ external power supply. Ever wonder why people complain about limited probe choice for the cheap scope brands? ;)

Another alternative would be the Tek AM502 differential amplifier, it is essentially the same circuit as the 7A22, but as stand-alone amplifier with BNC output. Gain is 100-100k with a switchable /100 attenuator. Bandwidth is 1 MHz with switchable high and low pass filter and DC offset, just like the 7A22. It merely requires a TM500 series power supply (eg. TM501), which is much smaller and lighter than a 7000 series scope. In both cases, you can either use 1x probes or special 10x probes as input (eg. Tek P6055). Normal 10x probes have a fair amount of tolerance in attenuation factor. Just 1% difference in attenuation will reduce the CMRR from 10,000:1 to 100:1.

There is currently one on eBay in as-is/dont-know-how-to-test condition for $100, but it looks modified. There appears to be a custom plate around the gain knob and the /100 attenuation button is missing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on December 09, 2012, 07:06:09 pm
Thanks a bunch for this alm  :-+, your deep insight and concise sum saves me a bunch of legwork for future eBay hunts.  Checking just now, some cost more than a mainframe +7A22 combined, but with patience, does one bag elusive prey. 

This has come up before, for example when Dave was so impressed by the Tek 2225 that went down to 500 uV/div....... snip .......
There is currently one on eBay in as-is/dont-know-how-to-test condition for $100, but it looks modified. There appears to be a custom plate around the gain knob and the /100 attenuation button is missing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on December 09, 2012, 07:11:20 pm
I have the 5 series version of that scope. The 2MHz differential plugin is great as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 09, 2012, 07:35:02 pm
I will make up a set of leads per the HP power supply handbook for the noise spike measurement and post results also. I have a 7A13 diff amp to do the 20MHz BW testing. That one was expensive $50.00  ::) it has a interesting infinite impedance mode for 50mV/div and below.

I will also make a more ideal short set of bnc/coax leads specifically for the PARD measurement.  I should have had the red leads in the PS with the PS off to measure the noise floor of the connections instead of just connected to each other. Any part of the de-energized PS that is picking up external noise that the CMR is not rejecting would show up.  We will see how much the test setup can be improved.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alm on December 09, 2012, 08:08:05 pm
Yep, there is also one for the 5000 series scope (5A22N?), and a slightly more limited version with a higher bandwidth. The 5000 series is much less popular, but sometimes also quite cheap because of their modest bandwidth. Not sure if they have signal out. The plugins look similar to the TM500 plugins, but they are not compatible (different pinout and keying).

The AM502 is not necessarily cheaper than the 7A22, but the mainframe is much more compact. It also has a full quality output, better than the signal out from 7000 series mainframes. I think I got a nice looking one for $70 or so. For old test equipment, there's almost always a test equipment vendor offering (usually not selling) one for a BiN price about 5-10x of what is reasonable in as-is condition.

The 7A13 is the other very interesting 7000 series plugin for which Tek did not make a stand-alone version. It has a large and accurate DC offset range that is very useful for signals superimposed on DC voltages. It also has an excellent overdrive recovery. Sensitivity is much lower than the 7A22/AM502, but bandwidth is much larger. The early mechanical version often had problems with cracked gears, but I'm sure that would not be a problem for someone with the mechanical knowledge of robrenz. I believe Preamble labs hired the 7A13 designer and developed a similar product (DA185x?). Don't expect to find it for $50.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 09, 2012, 08:41:21 pm
The 7A13 is the other very interesting 7000 series plugin for which Tek did not make a stand-alone version. It has a large and accurate DC offset range that is very useful for signals superimposed on DC voltages. It also has an excellent overdrive recovery. Sensitivity is much lower than the 7A22/AM502, but bandwidth is much larger. The early mechanical version often had problems with cracked gears, but I'm sure that would not be a problem for someone with the mechanical knowledge of robrenz. I believe Preamble labs hired the 7A13 designer and developed a similar product (DA185x?). Don't expect to find it for $50.

I have the late version 7A13 that has a mini LED display of offset voltage instead of the mechanical. I like that it has the offset voltage available on the front to monitor with a more accurate meter.

I also have a the Preamble 1855 $350.00 and the DXC-100  10X-100X differential probe box for it. It was $99.00 but had no probes so I got a set of replacement probes (service parts, they have to be soldered in)from LeCroy complete with all accessories for $70.00  This is good for 100MHz. When you read the calibration procedure for the DXC-100 you understand why maintaining CMMR with attenuating probes is difficult. There are 8 different pots/tuning caps per channel (16 total) in the probe box that need to be tweaked.   Those prices are way lower than what these items typically go for. (It pays to make stupid low offers)

The Preamble has a 100M ohm input mode. Do you guys think the 7A13 "infinite impedance" mode is higher impedance than the 100M mode of the Preamble?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alm on December 09, 2012, 09:28:28 pm
Yes, tweaking those old differential amplifiers is good fun. There is also the Tek P6046 differential probe that even Jim Williams called 'extraordinarily difficult to trim for CMRR'.

I don't think the 'infinite' input impedance is specified, but I would expect it to be much higher than 100 Mohm, at least in mint condition (dirt on the PCB may significantly reduce it). According to the schematic switch S10 sets the input impedance to 'electrometric', where it is directly driving the gate of a FET. DC impedance should be in the Gohms, AC will of course be much lower.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: muvideo on December 09, 2012, 10:26:20 pm
I have a 7A13 diff amp to do the 20MHz BW testing. That one was expensive $50.00  ::) it has a interesting infinite impedance mode for 50mV/div and below.

Very nice device the 7A22, I have a pair I bought for around 20€, the same seller wanted 105€
for the 7A13, so I'm still searching for the right one one ;)
The 7A22 can be modded in high impedance removing a pair of jumpers on the board,
it's limited to 10mV to 10uV per divison (since in this range the attenuator is not used)
and the input current in this config is quoted by the manual in the 100pA range, i.e. the
gate current of input fets.

Fabio.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 10, 2012, 03:53:55 am
@ muvideo,

Thanks for the heads up on the high impedance mode. I missed that in scanning the manual.

Do your 7A22's have the awesome machined tuning capacitors like mine in  this thread? (https://www.eevblog.com/forum/chat/reunion-with-my-first-scope-after-32-years/msg157326/#msg157326). The manual I downloaded shows regular tuning caps in the manual.  The jumpers that get unsoldered for the high impedance mode are shown in those pics also.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: muvideo on December 10, 2012, 09:55:55 am
@ muvideo,

Thanks for the heads up on the high impedance mode. I missed that in scanning the manual.

Do your 7A22's have the awesome machined tuning capacitors like mine in  this thread? (https://www.eevblog.com/forum/chat/reunion-with-my-first-scope-after-32-years/msg157326/#msg157326). The manual I downloaded shows regular tuning caps in the manual.  The jumpers that get unsoldered for the high impedance mode are shown in those pics also.

It's exactly the same:
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34403)
(https://www.eevblog.com/forum/reviews/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=34405)
By the way one of the mine was broken. One of the problems was
due to a deformed variable capacitor, pushed by the offset pot the
armatures were touching and it was shorted.
The other problem was a resistor cosmetically perfect but electrically
open, before I started checking the resistors I swapped all the
semiconductors and capacitor in that stage.
I was so amused by the fact that it's entirely passive design,
the schematic seem "simple" for the specs, but as everything the
devil is in the details.

In this case the high impedance mod precludes the use of the higher
input voltages, at least trows off the calibrated amplitude since the
attenuator expects to have there the 1Meg input resistor.
One could think to use a pair of switches or jumpers or reed relays
to connect and disconnect easily these jupers, but must be
careful with the eventual introduction of thermocouples with
the contacts.

Fabio.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 10, 2012, 09:19:06 pm
That is one kick ass microvolt input scope!  Few can match it today, most top scopes do 500uV/div as minimum, if at all.  Not to mention the dynamic range, 10uV to 10V /div, it took a while to look at that range before I realized it was true!

It does at least 25V/div. in variable.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Fsck on December 31, 2012, 07:14:15 pm
So my 2020B has a busted voltage selector switch. (The 0-10v vs. 10-20V & pull to release switch)
Anyone know where I can find a reasonably priced replacement? It's the pull to release switch function that I'm unsure of how to replace. Like a on-off-on dpdt toggle switch?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 31, 2012, 08:18:11 pm
AFIK You can use any good quality 2 position (on none on) double pole switch. It needs to be fairly good quality because the controlling resistance goes thru one set of contacts. It does not need to be high power, I think only one milliamp goes thru the controlling resistance and the other contacts just power the neon indicators.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 05, 2013, 04:17:57 am
So I just got a 2020B, I haven't done a full rundown of it yet, but as I was unpacking it I heard something rattling, and found this screw inside:
(http://i.imgur.com/YYiNkl.jpg)

But I can't seem to find where it's from.  :-// I can't see how it would have got in there, but nothing seems to be missing. Anyone have any idea?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: justanothercanuck on January 05, 2013, 04:38:34 am
Ouch!  Good thing you didn't turn it on...  Does it look like it came from the power supply?  Your guess is as good as mine, but maybe when they were assembling them, the lineworker accidentally dropped it in there, couldn't retrieve it and let it run down the line.  :-//
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 05, 2013, 05:25:59 am
I figured it out. The rear feet are missing, and this screw matches the screws in one of the front feet. Oddly the other front foot uses Philips screw heads. :o

I wonder where the screw for the other foot went...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 10, 2013, 01:23:47 am
Interesting, it seems someone replaced the second fuse with a 3/4 amp fast blow fuse. I was  |O until I realized there was no reason it should be that small, looked in the manual, and yep, should be 3 amp slow blow.

Before it blew I made this graph:
(http://i.imgur.com/tKjd4.png)

Between 2-10v it's less than 100ppm off. Just for fun I tested with a Fluke 87V. Any point in the graph just means it was one or two counts off. This is all without cleaning any contacts. I need to figure out this deoxit thing and clean them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on January 10, 2013, 02:52:36 pm
That a nice graph.  Chances are if you deoxit the contacts you could extend the 100ppm error to the smaller voltages,  cleansing off oxidation and contact grime play a large role in the reading stability.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 11, 2013, 03:18:26 am
Thanks, I also have a much less impressive one for my EDC 520 and even less impressive for my 2005 :(. I'm hoping it's just serious corrosion.

About the deoxit, I'm probably going to get the d100l 2ml tube and a lot of wooden cotton swabs and go to town. I wish there was a less complicated way to take the front panel apart, it's going to be a pain to clean.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on January 11, 2013, 03:55:09 am
IMO don't take it apart. Get the white handle Microbrush (http://www.microbrush.com/automotive/products/microbrush/index.asp) to apply the Deoxit. Cotton swabs will waste a huge amount of the very expensive stuff. Just wet each each contact with D100L and then cycle the switch a lot. Wash off with your favorite electronic cleaner and blow out. Then lightly lube each contact with Deoxit G100L with another white microbrush. I competely agree with using the liquid (not spray) versions of deoxit.  HERE (https://www.eevblog.com/forum/projects/diy-flux-dispenser-bottle/msg152664/#msg152664) is my setup.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 11, 2013, 01:38:39 pm
IMO don't take it apart. Get the white handle Microbrush (http://www.microbrush.com/automotive/products/microbrush/index.asp) to apply the Deoxit. Cotton swabs will waste a huge amount of the very expensive stuff. Just wet each each contact with D100L and then cycle the switch a lot. Wash off with your favorite electronic cleaner and blow out. Then lightly lube each contact with Deoxit G100L with another white microbrush. I competely agree with using the liquid (not spray) versions of deoxit.  HERE (https://www.eevblog.com/forum/projects/diy-flux-dispenser-bottle/msg152664/#msg152664) is my setup.

Yeah, I was lamenting because I tried and realized it'd be a nightmare with a lot of blood, tears, and probably destroying something. Makes me wonder how they put it together.

Thanks so much for the pointers. I now have some brushes and deoxit d5 and gold on the way.

Just for fun, here's a look at how bad my 2005 is:
(http://i.imgur.com/80O3l.png)
I didn't bother going beyond 100mV because it was worse than 100%. All the lamps are dead too. :'( And it killed my dog. And gave me indigestion. And set my car on fire.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on January 13, 2013, 12:15:54 pm
Its worth the labor, PSU with these types of stability specs are  sold today as 'source units' by Agilent, and the starting price is > 10x more than you'd pay for even the most expensive PD supply, which unfortunately, as I still track may units on eBay, the base price is now 2x what I paid for it.  So maybe eBay folks read eevblog.  Enjoy.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 22, 2013, 04:16:52 pm
So here's my progress:
(http://i.imgur.com/vvbP7fe.png)

So I'm kind of confused. As you can see, after I cleaned it all the peaks and valleys are gone, which I thought made sense, but then when I calibrated it, they came back, and it's nowhere near as accurate as I thought it would be. Zero didn't really need to be adjusted all that much, it was at about -0.8mV, but I got it to within 0.5uV, then at 20V I got it to 20.005V.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on January 22, 2013, 06:05:52 pm
May I suggest first doing a repeatability test of each decade independently. Maybe 5 to 10 data points thru each position and measure the min-max and SD of each of the 10 positions.  Do this separately for each decade, don't move the other decades while doing the test and cycle 0 thru 9 and back to 0 this may show difference in value for approach direction. If you have another very stable supply you could use it to offset the higher voltages to your meter for increased resolution. In this test we are only looking for repeatability  not absolute accuracy.  These are 1 ohm per mVolt units so that is a mOhm per microvolt so the switches need to be really well cleaned and lubed. You also may want to check the phasing of each decade with the detent to make sure the switch contacts are well centered when in the detent position. The detent system itself needs to be in good shape, some of mine had some very hard caked grease that was particularly hard to remove.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on January 22, 2013, 11:07:57 pm
The green line is expected, the blue line is erratic and suggestive of dirt; the yellow line now appears similar.

I suspect the calibration pot has oxidized grit; once manipulated the dirt is catching on the pot wiper arms.  Try turning the adjust multiple times back and forth to clear out the grit and see what happens.   I can't recall if the cal pot is hermetically sealed or not, and amenable to dexoit cleaning.


So here's my progress:
(http://i.imgur.com/vvbP7fe.png)

So I'm kind of confused. As you can see, after I cleaned it all the peaks and valleys are gone, which I thought made sense, but then when I calibrated it, they came back, and it's nowhere near as accurate as I thought it would be. Zero didn't really need to be adjusted all that much, it was at about -0.8mV, but I got it to within 0.5uV, then at 20V I got it to 20.005V.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 24, 2013, 06:59:18 am
So here're the results of a quick test Rob suggested:

Avg: 5.002337
Min: 5.00231
Max: 5.00235
SDev: 0.0000125166555704632

Avg: 0.5005721
Min: 0.500546
Max: 0.500592
SDev: 0.0000135273385737515

Avg: 0.04995493
Min: 0.0499536
Max: 0.0499577
SDev: 0.00000138246960987263

Avg: 0.004990644
Min: 0.00498626
Max: 0.00499526
SDev:0.00000330608260970913

It's interesting that the 10 and 1 mV decades are all below where they should be, while the 1V and 100mV decades are all above. Something I forgot to mention: the contact for the second set of resistors on all decades only appears to make contact between each setting. Is that normal? The entire rod is indexed, so I don't see how it could be off that much. Otherwise the contacts appear to line up right.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on January 24, 2013, 04:00:36 pm
Lets put this in perspective.  The spec for the 2020 is 0.1% of setting plus 500µV. 
Lets not even consider the additional 0.001% regulation, 8 hour stability of .001% + 100µV, and TC of 0.001% or 50µV whichever is greater/ deg C.

Min: 5.00231   that is 40µV variation (.36% of a .011V error band)     Max error is .00235V spec allows .0055V  less than 42% of spec.
Max: 5.00235      +.047% of set value error.

Min: 0.500546   that is 46µV variation (2.3% of a .002V error band)    Max error is .000592V spec allows .001V  less than 59% of spec.
Max: 0.500592    +.118% of set value error.

Min: 0.0499536    that is 41µV variation (3.7% of a .0011V error band)    Max error is .0000464V spec allows .00055V  less than 9% of spec.
Max: 0.0499577   -.093% of set value error.

Min: 0.00498626   that is 9µV variation (0.89% of a .00101V error band)    Max error is .00001374V spec allows .000505V  less than 3% of spec.
Max: 0.00499526     -.275% of set value error.

This is all well within the original specifications.  :-+  Those microvolt variations are milli ohm variations in contact resistance.  It is fun to try to improve it further.  :-/O
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: poodyp on January 25, 2013, 02:01:52 am
Lets put this in perspective.  The spec for the 2020 is 0.1% of setting plus 500µV.

Actually I forgot to point out this is my 2005, my 2020B is already pretty good. I'm hoping it can get better after being cleaned.

Quote
Lets not even consider the additional 0.001% regulation, 8 hour stability of .001% + 100µV, and TC of 0.001% or 50µV whichever is greater/ deg C.

Min: 5.00231   that is 40µV variation (.36% of a .011V error band)     Max error is .00235V spec allows .0055V  less than 42% of spec.
Max: 5.00235      +.047% of set value error.

Min: 0.500546   that is 46µV variation (2.3% of a .002V error band)    Max error is .000592V spec allows .001V  less than 59% of spec.
Max: 0.500592    +.118% of set value error.

Min: 0.0499536    that is 41µV variation (3.7% of a .0011V error band)    Max error is .0000464V spec allows .00055V  less than 9% of spec.
Max: 0.0499577   -.093% of set value error.

Min: 0.00498626   that is 9µV variation (0.89% of a .00101V error band)    Max error is .00001374V spec allows .000505V  less than 3% of spec.
Max: 0.00499526     -.275% of set value error.

This is all well within the original specifications.  :-+  Those microvolt variations are milli ohm variations in contact resistance.  It is fun to try to improve it further.  :-/O

So, don't worry about the accuracy, just be happy the repeatability and drift are good (I measured it at 6uV at 12 hours so far)?

The green line is expected, the blue line is erratic and suggestive of dirt; the yellow line now appears similar.

I suspect the calibration pot has oxidized grit; once manipulated the dirt is catching on the pot wiper arms.  Try turning the adjust multiple times back and forth to clear out the grit and see what happens.   I can't recall if the cal pot is hermetically sealed or not, and amenable to dexoit cleaning.

The pots aren't sealed as far as I can tell, but I'm not sure how I'd open them without destroying them. I tried wiping them back and forth several times, but it doesn't seem to have made any difference.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on January 25, 2013, 03:20:00 pm
Lets put this in perspective.  The spec for the 2020 is 0.1% of setting plus 500µV.
Actually I forgot to point out this is my 2005, my 2020B is already pretty good. I'm hoping it can get better after being cleaned.
That makes it even better! The spec for the 2005 is 0.1% of setting plus 1mV.

So, don't worry about the accuracy, just be happy the repeatability and drift are good (I measured it at 6uV at 12 hours so far)?
Not at all,  %-B just realize it is way better than its spec and improving it is going to take some very precise tongue angle :-/O

I suspect the calibration pot has oxidized grit; once manipulated the dirt is catching on the pot wiper arms.  Try turning the adjust multiple times back and forth to clear out the grit and see what happens.   I can't recall if the cal pot is hermetically sealed or not, and amenable to dexoit cleaning.
The pots aren't sealed as far as I can tell, but I'm not sure how I'd open them without destroying them. I tried wiping them back and forth several times, but it doesn't seem to have made any difference.
One way you could check them is to disconnect one end of the pot and connect your ohm meter between there and the wiper and see if there are jumps in the readings as you travel the zone you have been using. If the ohm range crosses two of your meter ranges make sure you lock your meter into the higher range so you dont think the jump when auto ranging is a bad pot.  I did that earlier in this thread :-[   You can also do the standard contact resistance variation test shown in the bourns potentiometer handbook (http://www.bourns.com/data/global/pdfs/OnlinePotentiometerHandbook.pdf)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on January 25, 2013, 06:46:35 pm
If the pots do seem bad and you want to try cleaning them before you replace them you can use the method described on page 2 of this thread on posts #18 thru #22.  look at the typical construction of this type of pot on page 8 of this download of the   Bourns trimmer primer (http://ordering.digikey.com/DocumentRedirector.aspx?doc=http://www.digikey.com%2fWeb%20Export%2fSupplier%20Content%2fBourns_118%2fPDF%2fBourns_TrimmerPrimer.pdf).  Guesstimate the location of a small hole at each end that will allow you to blast stuff through the pot with a syringe. Either manual or air powered (solder paste dispenser) I suggest a sequence of lots of IPA folowed by just air then a small drop of deoxit D100L. Cycle the pot multiple times to work the  deoxit.  Then wash again  with lots of IPA and air dry. Then a small drop of Deoxit fader lube to lube the pot and cycle again to spread the fader lube. Deoxit G100L will work if you don't have the fader lube.

You can do all this without removing the pots from the base board since they are laying on thier sides.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on March 02, 2013, 07:10:11 am
Im pretty happy.  After over a year of wanting another PD PSU I finally got a 2020B;
http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160 (http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on March 02, 2013, 02:47:20 pm
Im pretty happy.  After over a year of wanting another PD PSU I finally got a 2020B;
http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160 (http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160)

You should be happy, these are things of beauty  ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on March 02, 2013, 02:59:33 pm
@ c457p

How are you accessing the need for resistor trims? Measuring the individual resistors or extracting which resistors are contributing to a voltage error from the rather complex switching matrix? (which I have not spent the time to understand yet  :-[ )

Thanks for any help.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on March 02, 2013, 03:23:28 pm
Plenty of nice ones, but the shipping......... :( is not nice.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on March 02, 2013, 03:32:49 pm
When I noticed a couple settings were out more than I'd like, I just looked at the switch contacts to see which resistors were involved, disconnected them and measured. Sheer dumb luck allowed me to be correct the first time twice in a row  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on March 02, 2013, 03:42:37 pm
Plenty of nice ones, but the shipping......... :( is not nice.

Yeah, shipping to South Africa doesn't sound fun. It's not bad to get them across the U.S.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on March 02, 2013, 05:25:57 pm
Im pretty happy.  After over a year of wanting another PD PSU I finally got a 2020B;
http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160 (http://www.ebay.com/itm/Power-Designs-2020B-Variable-Power-Supply-Precision-DC-Calibrator-2AMP-20V-/221195966773?ssPageName=ADME:L:OC:US:3160)

You should be happy, these are things of beauty  ;D

Is there anything I should do when I get it?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on March 02, 2013, 05:33:59 pm
Yes,  read thru this thread from the beginning.   I am serious, there is a lot of good info from lots of people in here.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on March 02, 2013, 05:41:56 pm
Is there anything I should do when I get it?

I will contribute a suggestion that is not specific to this power supply, but still, would have bit me in the ass with mine if I forgot. This applies to all of this old equipment, as it has had many years to break and be fixed by people of significantly varying capability. Don't turn it on, take it apart - check for idiotic, bodgy "repairs" that may have fallen apart over time and may cause trouble. The jackass who had mine before me couldn't even replace a neon indicator without allowing mains potential to short to the chassis - looks like the joint was loosely covered and came undone during shipping.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: terabyte on March 02, 2013, 06:02:26 pm
Ok thanks guys.  This thread was just a little overwhelming to read the entire thing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on March 02, 2013, 08:33:08 pm
Try statistical summarizers, they tend to get a good executive summary even with technical information; it uses pattern matching so the language or topic is not material.  Try  and see.  Its one of the best features of Microsoft Word that I know most people don't know exists, its been there since the beginning.

There are similar ones online.  To summarize an eevblog page:

Hit print icon on the top of each forum topic, it will create a URL:

https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=printpage (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=printpage)

You can print it to read or port it for reading later, like a textbook.

To get an executive summary go to say, here:

http://www.tools4noobs.com/summarize/ (http://www.tools4noobs.com/summarize/)

Plug in the print output URL on the address and enjoy the bullet items.

You can play with the summarizer options when you get comfortable with what it does.



Ok thanks guys.  This thread was just a little overwhelming to read the entire thing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on May 04, 2013, 04:54:18 pm
Has anyone tried to modify these power supplies? I see that the 2020B uses a fairly old and obsolete op amp as the voltage control amp (uA798HC) which is rather slow.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: andyb on May 04, 2013, 05:45:18 pm
I've got one for sale over in the Buy / Sell area

https://www.eevblog.com/forum/buysellwanted/fs-power-designs-pd-2005- (https://www.eevblog.com/forum/buysellwanted/fs-power-designs-pd-2005-)$50/
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on May 15, 2013, 11:20:04 pm
I purchased a 2020B the other day. It appears to work fairly well if a little out of cal. Upon looking inside, I notice that the LM399 has a small scorch mark on it. Is this common? I haven't tested the unit for drift yet but I will shortly.

EDIT: doesn't drift much over a few hours.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on May 16, 2013, 06:18:33 am
LM399's tend to run at 70C, so it will look a little toasty when powered up for a few years.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on May 16, 2013, 07:34:18 pm
Thanks for the reply. It seems to be working well and everything is stable so I'll leave it for now but may order a new LM399 in the future "just in case". I see they are currently running around $12-$14 on ebay.. about the same as the DK price.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on May 17, 2013, 01:46:40 am
Picked this one up at a swap meet last week for $20.  0-50 V/.5 A
I'm happy.

(http://www.stevenjohnson.com/web-pics/powerdesigns5005R.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 17, 2013, 12:00:57 pm
It looks to be in fine shape and has all original knobs  :clap:.  I presume its Vout is factory stable perfect  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 17, 2013, 12:20:54 pm
Nice one SLJ :-+

I just bought a 6050A from the buy sell on this fourm for $75.00 including shipping.

@ saturation  I think we are tie now ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on May 17, 2013, 05:43:46 pm
It looks to be in fine shape and has all original knobs  :clap:.  I presume its Vout is factory stable perfect  :-+

Stable, no AC ripple to speak of, and the meter is accurate.  :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 22, 2013, 06:51:54 pm
Fully functional thing of beauty.  The control amplifier picks from 4 different rectified voltages with transistors/diodes to keep the power dissipation low (trademarked "UNIPLY"). No relay clicking in this one.  Bought a real manual from manuals plus for $25.00 (could not find a pdf anywhere) I especially like the fact that the form factor is the same as the precision supplies.
(https://www.eevblog.com/forum/chat/show-your-favorite-and-mostly-used-benchtop-psu/?action=dlattach;attach=48497;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: manticore00 on June 05, 2013, 07:14:04 pm
My wife's going to kill me but I caught this bug too after reading through this thread and I picked up a 6050A from ebay for less than $70, including shipping. I don't really need it but the quality and beauty seduced me. Trying as hard as I can to resist the call of the Tek 7000 series scopes...

Am I the only one who wishes that some company would match the aesthetic beauty of older equipment with the features and functionality of modern ones?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 05, 2013, 07:30:52 pm
As you can tell, you are not alone ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on June 05, 2013, 10:18:52 pm
Amen,  :-+ but on those low noise PD supplies, you'd be hard pressed to find an equal in any era, from the past to today not just the look, but the function.

https://www.eevblog.com/forum/chat/what-is-a-good-power-supply/ (https://www.eevblog.com/forum/chat/what-is-a-good-power-supply/)

https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg103401/#msg103401 (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg103401/#msg103401)

Some recaps of their history.   

Thus, its worth owning, it gives you some of the quality of a precision source,  even in PD's more 'ordinary' bench PSU.  Overall, the quietness of their supplies are closer to an ideal PSU, i.e., a variable 'battery', than most PSU made today, and the precision types are only bested by a more exotic device that costs 100X more, granted the new ones also do more.

http://www.home.agilent.com/en/pd-2149890-pn-B2961A/65-digit-low-noise-power-source?nid=-33090.1035018&cc=US&lc=eng (http://www.home.agilent.com/en/pd-2149890-pn-B2961A/65-digit-low-noise-power-source?nid=-33090.1035018&cc=US&lc=eng)

But if you are so inclined, your small lab has the capacity to do a level of low noise work  :clap:, heretofore reserved to only professional or far better financed labs.

Jim Williams had some and I'm sure he'd agree if he were still around.




My wife's going to kill me but I caught this bug too after reading through this thread..
Am I the only one who wishes that some company would match the aesthetic beauty of older equipment with the features and functionality of modern ones?
As you can tell, you are not alone ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 07, 2013, 05:54:52 pm
So I just received a beautiful Keithley 196 61/2 digit dmm and thought I would put my 2020B through its paces. While working through the voltages I noticed that the 10v and 20v ranges where about 100mv out of sync. I could cal either range to within 20uV but then the other range would be out by 100mV. I checked the 10K 3W precision power resistor that the range switch affects and found it to be 10.02K (10.01773K on 4 wire  O0 ). So that is not 0.01%... no where near. Using a resistance box I found that paralleling 4.7MOhm (how convenient!) would bring me close enough to within 50uV on either range. Looks like these older power resistors drift with time (use?), just something to look out for.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 07, 2013, 07:23:17 pm
My wife's going to kill me but I caught this bug too after reading through this thread and I picked up a 6050A from ebay for less than $70, including shipping. I don't really need it but the quality and beauty seduced me. Trying as hard as I can to resist the call of the Tek 7000 series scopes...

If she kills you can I have yours?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: manticore00 on June 07, 2013, 08:20:41 pm
The 6050A arrived today and outwardly everything appears to be good and aside from being a bit dusty the inside appears good too, all fuses are intact and no obviously failed or damaged components.

That said, I've found that the 6V range won't output anything above 4.1 volts and when I switch to the 60V range I can dial it up to 9 volts but anything beyond that and the voltage drops suddenly and I hear a faint clicking noise coming from inside the unit. The overvoltage crowbar is rotated to the maximum clockwise position and I've dialed up the current limited pot and switch but that made no difference.

I plan on trying a more thorough examination over the weekend but I thought I'd see if anyone here has any immediate thoughts or suggestions?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: onlooker on June 10, 2013, 11:15:03 pm
For those interested, 3 PD6050A are on ebay BIN now (not by me) for ~$28 each with FS. I guess they are not going to be there for long.

http://www.ebay.com/itm/Power-Designs-6050A-Power-Supply-/181156023030?pt=LH_DefaultDomain_0&hash=item2a2dbd8af6 (http://www.ebay.com/itm/Power-Designs-6050A-Power-Supply-/181156023030?pt=LH_DefaultDomain_0&hash=item2a2dbd8af6)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on June 10, 2013, 11:21:59 pm
That was fast.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 10, 2013, 11:44:54 pm
Real bargains there but the time shipping goes in... its no longer a bargain for me. There where a couple of working 6050D's a few weeks ago for $49 a piece but shipping to me was $125 for the two. These supplies often get overlooked and undervalued because they are not HP/Agilent or Lambda.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: onlooker on June 10, 2013, 11:45:39 pm
They are gone! Who had them?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 12, 2013, 12:13:05 pm
Just an FYI and I don't know if this has been posted yet but here is a nice redo of a Power Designs model 2005 manual:
http://www.rako.com/Articles/29.html (http://www.rako.com/Articles/29.html)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: manticore00 on June 21, 2013, 02:53:56 am
Ordered a Power Designs 2010 about a week ago and it showed up today. Right off the bat I was kind of worried because the front panel was bowed out from the case in a way that looked like it had been dropped...

Went into my lab to power it on and immediately noticed that the V/A meter wasn't moving as I moved up and down the voltage values, but after hooking it up to my bench DMM the output itself was absolutely perfect to all four digits so that made me much happier :-+

I cracked open the case and after probing around a bit I couldn't see anything wrong with the wiring or parts(other than the meter) so I ended up taking the meter out to examine it and in the course of that effort the needle migrated from the bottom of the scale to the middle and wouldn't budge at all... Long story short, I ended up taking the case of the meter apart and discovered that some ancient blue insulation tape on the inside was fouling the free flow of the needle and after replacing it with some brand new black electrical tape everything now works perfectly.

Thought I'd share incase anyone else ever sees something like this in the future and could do with a troubleshooting idea.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 21, 2013, 10:18:45 am
Thought I'd share incase anyone else ever sees something like this in the future and could do with a troubleshooting idea.

Thanks for sharing.  I have a 2005 on the way.  Looks like the output is OK but the meter/dials are a little off so it will need some calibration and there is no oven light or main power indicator lit so it will be an interesting project.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 21, 2013, 11:07:37 am
It looks like the epidemic is spreading >:D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 21, 2013, 12:21:37 pm
It looks like the epidemic is spreading >:D

This will be number two for me (already have a 5005R) and I'm keeping an eye out for a good deal on a 6050A.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: manticore00 on June 21, 2013, 02:01:59 pm
I've also got a TP340 that works perfectly(but had a huge dent in the case that needed some percussive maintenance to correct) and a 6050A that appears to have a faulty current pot. I stripped the 6050A down a couple days ago and near as I can tell when the voltage go over about 8v there's an arcing noise and the current goes through the roof. I looked at the pot itself and it doesn't look like there's an easy way to get inside of it  :-\
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: KarlMonster on June 21, 2013, 04:03:50 pm
Many thanks for this thread.

I was Power(Supply)less and needed something to drive Op Amps and help me to release the majik smoke from my dormant ICs.
[I used a looped AND-NOT logic gate to verify that my new 'Scope (with wonky CAL function) was really working!]

I literally had a Sinometer/Mastech HY3005F-3 triple linear PS in my shopping cart when I found this thread. Instead of that, I got one of many TPI 340s that are on eBay right now. I know I'm going to be pleased with it - 'cause it was half the cost.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 26, 2013, 09:27:00 pm
(http://www.stevenjohnson.com/web-pics/powerdesigns2005-5005R.jpg)

The 2005 arrived yesterday.  After a new power cord and a slight tweak it's dead on at 5.000 volts.  When you get it up to 20 volts it's off by about .02 volts.  Close enough for my use and until I find a service manual.  It took me longer to get three cal and inventory stickers and their goop off the front panel.
They do look nice stacked.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 27, 2013, 02:11:15 am
(http://www.stevenjohnson.com/web-pics/powerdesigns2005-5005R.jpg)

The 2005 arrived yesterday.  After a new power cord and a slight tweak it's dead on at 5.000 volts.  When you get it up to 20 volts it's off by about .02 volts.  Close enough for my use and until I find a service manual.  It took me longer to get three cal and inventory stickers and their goop off the front panel.
They do look nice stacked.
My god that's attractive.... ahem...

Try putting it to 10V on the 20V range (dial reading 0.000) and see if its still 0.02V out. If it is then its probably the 10K range resistor moving out of tolerance (assuming the 2005 is similar in the divider network to my 2020B).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on June 27, 2013, 02:21:11 am
Remember that each voltage is switched in by individual, discrete resistors. There are a million places where that error could come from. If the error is linear with the set voltage, it's a calibration error, just adjust the trimpot (you're supposed to do it at 20.000V). Let both the PSU and the voltmeter you're checking it with warm up (fully turned on, not just standby) for a long time before you do this. If if's not, you'll have to track down which resistor it's from. I too suspect the +10V switch - if you get the same 20mV error going from 10 to 20 and from 0 to 10, check that. Otherwise, open it up and start probing resistors (for each one, you'll have to find a knob position that gets it out of the circuit). I suggest adjusting them by adding a small series resistor or large parallel resistor. The ones that are in there are already quite aged and should not drift too much more, and it's probably best to take advantage of that. Adjust the resistance according to output voltage, not to what the resistor is marked with.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 02:30:55 am
The 2005 arrived yesterday.  After a new power cord and a slight tweak it's dead on at 5.000 volts.  When you get it up to 20 volts it's off by about .02 volts.  Close enough for my use and until I find a service manual.

The manual is here (http://www.rako.com/Articles/29.html) from post#10 of this thread :-[. Calibration procedure is there.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on June 27, 2013, 02:40:01 am
Thanks,  I had forgotten about the link to the manual for the 2005 being posted here.  It's only the 10-20V range thats out (across the entire range) so it looks like I will need to check the trimmer and resistor for the upper range.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on June 27, 2013, 02:44:09 am
Lucky... Mine had a whole bunch of resistors out. Not sure if it was a bad batch of resistors, or if the unit was just treated with particular disrespect.

Actually, given how the front panel was mangled to fit in replacement neons (a different size), I'd say it's probably the latter...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 02:49:37 am
There is only a zero adjust and a 20V adjust. You dial in the 20 after the zero. If 10V is off after that check the 10k resistor that is shorted by the 10-20 range switch. If 5V is off after that a Deoxit cleaning of the decade switches should get it in tolerance from my experience.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 27, 2013, 03:20:53 am
Thanks,  I had forgotten about the link to the manual for the 2005 being posted here.  It's only the 10-20V range thats out (across the entire range) so it looks like I will need to check the trimmer and resistor for the upper range.

Its almost certainly that 10K 0.1% (R45) range resistor. Pull the RV to S+ strapping out and measure across the resistor. Mine measured high so I paralleled a couple of 10Mohm resistors to it and its bang on the money now.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 03:34:49 am
We cant make that assumption until SLJ calibrates zero and at 20V and then checks 10V on the 10V scale. The 5V is affected by the decade switches and resistors.  The 20V being off means it needs calibrated before you can do any other testing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 27, 2013, 03:39:19 am
We cant make that assumption until SLJ calibrates zero and at 20V and then checks 10V on the 10V scale. The 5V is affected by the decade switches and resistors.  The 20V being off means it needs calibrated before you can do any other testing.
Thus my "almost". But if its out in the entire 20V range by the same amount and not in the 10V range at all, then that would be my guess. Its easy to check anyhow.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: GK on June 27, 2013, 04:38:36 am
The 2005 arrived yesterday.  After a new power cord and a slight tweak it's dead on at 5.000 volts.  When you get it up to 20 volts it's off by about .02 volts.  Close enough for my use and until I find a service manual.

The manual is here (http://www.rako.com/Articles/29.html) from post#10 of this thread :-[. Calibration procedure is there.



Very simple design, electrically. Checked out some of the other stuff on Mr Rako's site. Yet another personality from the semiconductor industry appears to be somewhat "out there":

http://www.rako.com/Apostate/44.html (http://www.rako.com/Apostate/44.html)

 ::)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: GK on June 27, 2013, 07:24:56 am
So what kind of legitimate applications are these PD supplies being used for, where their accuracy is actually required?

The lack of remote sensing facilities strikes me as odd.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 11:16:36 am
Discussion of that on this thread starts here (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg114685/#msg114685) Besides being more precise than the meters most many people would use to check them they have incredibly low noise and excellent long term stability.  You have to pay over $5000 dollars from Agilent to get a supply with noise performance this low. Why would you not buy these when they are less expensive than a lot of new junk

They do have remote sensing and programming.

Signed:
Power Designs Cult Co-leader ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: GK on June 27, 2013, 11:44:14 am
Looking at those photos posted by SLJ I just assumed remote sensing wasn't a feature as there are no appropriate/bridgeable binding posts on the front panel besides the output binding posts for the purpose.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 11:55:19 am
No problem, your forgiven, as long as you have a glass of coolaid on us :scared: :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 27, 2013, 02:14:23 pm
Most of these older supplies put them on a barrier strip on the back.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JBeale on June 27, 2013, 09:39:54 pm
I am checking out an old Power Designs Model 2005A which has been sitting in a garage for a long time. I don't have anything to check it with better than a Keithley 196 DMM (from ebay, and 4 years out of calibration).  The 2005A seems to mostly work.  After warmup, the OVEN lamp flickers sometimes as it probably should, and the indicated voltage output drifts less than 20 ppm in one day.  However, pressing on or slightly jiggling any of the four rotary voltage selectors shows some jumpiness in the output, so clearly there are dirty contacts. I haven't taken it apart yet. Are these contacts copper, silver, gold, something else? Is a spray with contact cleaner likely to help, or will a full disassembly and/or replacement be the only cure?  I have seen Caig DeoxIT recommended, but they seem to sell many different varieties for different contact metals and situations.

(https://lh3.googleusercontent.com/-uLv7J8NtVgc/UcysygbsMWI/AAAAAAAADEY/n6I776j65Go/w548-h666-no/IMG_5602.JPG)

Update: ironically, *as I was writing this post* the Keithley's LED display blinked out (it had been working without issue for months). The internal analog +/- 15V power rails are still ok... anyway, a problem for another post.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 27, 2013, 10:21:41 pm
I suggest compressed air first if you have it to remove all dust that will blow off. Then a thourough wash with a general electronic cleaner to get the general gunk off the switch assemblies and the detents.  The detents will probably have caked old grease in the ball pockets. Then apply deoxit D100L to all the contact fingers and thoroughly cycle the switches. Re lube all the places where the switch shaft engages other parts and grease the detent assemblies. I personally like wash the D100L off and then lubricate with Deoxit G100L.

some links from this thread here (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg180173/#msg180173)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on June 27, 2013, 11:06:33 pm
OK - since this is the Power Designs mecca thread...

I have a TW5005W. Lovely supply. Mine needed a couple electrolytics replaced when I received it but has otherwise aged very gracefully.

Only thing is that I am kind of a stickler for cleanliness. I removed all the stickers from it. Got rid of all the adhesive gunk from beneath the stickers. But unfortunately, some of the stickers had been on there... a long time. So the metal front panel (Aluminum I think?), has yellowed in all places except where the stickers were (oh, and also beneath the knobs). Beneath the stickers and knobs, the color is fine. I noticed a bit of acetone gets rid of the yellowing, but I'm worried that the acetone will remove all the silkscreened labels so I have not pursued that.

Any suggestions for getting rid of the discoloration? Any idea what it is?

Sorry to not talk about their precision supplies. I have one of those too - a 5020 - but it hasn't needed any work and also still looks pretty.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on June 28, 2013, 12:18:29 am
Have you tried magic sponges?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on June 28, 2013, 12:25:01 am
Have you tried magic sponges?
No but I don't trust those things - they're pretty much just normal sponges mixed with sand and chemicals. I think they'd take off the silkscreen as well as the yellowing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on June 28, 2013, 12:30:53 am
Have you tried magic sponges?
No but I don't trust those things - they're pretty much just normal sponges mixed with sand and chemicals. I think they'd take off the silkscreen as well as the yellowing.
Usually, they are made from melamine foam (http://en.wikipedia.org/wiki/Melamine_foam).

Quote
It is also the component of Magic Eraser and similar cleaning products.

As long as the surface you are cleaning is not softer than melamine, it will not scratch. Silkscreen may be an issue.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: dave3533 on July 01, 2013, 06:47:12 am
When you guys are cleaning the decade voltage knobs, are you removing them from the supply or just cleaning them in place?  If you are removing them, how difficult is it?

Thanks!
 8)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on July 01, 2013, 11:55:48 am
I cleaned mine in place.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on July 01, 2013, 03:45:50 pm
In place. QTip and IPA.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on July 01, 2013, 03:47:23 pm
If you are removing them, how difficult is it?

Don't even think about it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: dave3533 on July 02, 2013, 02:32:17 am
Don't even think about it.
:-+ I figured that was probably the case  ;D

I purchased this 5020 on ebay and it was in poor shape initially.  The circuit board visible from the top of the unit was coated in black dust.  I've used denatured alcohol to clean most of the grime out (think I have about 3 hours of cleaning into the top circuit board  :o). 

I still haven't figured out the best way to clean the front aluminum, any suggestions?

(http://i168.photobucket.com/albums/u186/dave3533/5020front_zpsf5266a08.jpg)
(http://i168.photobucket.com/albums/u186/dave3533/5020top_zpsd40c2f1c.jpg)
(http://i168.photobucket.com/albums/u186/dave3533/5020bottom_zpsd2ec1aae.jpg)

I also noticed that the circled component below seems to have a "loose" top, ie it will wiggle and slightly rotate.  I've essentially left it alone for now to prevent damage, as the supply seems to work well regardless.  I'll look up the component after I finish cleaning.

(http://i168.photobucket.com/albums/u186/dave3533/5020inductor_zpsfe71b1bb.jpg)

Once I finish cleaning it I'll put it through its paces :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on July 02, 2013, 02:38:44 am
I also noticed that the circled component below seems to have a "loose" top, ie it will wiggle and slightly rotate.  I've essentially left it alone for now to prevent damage, as the supply seems to work well regardless.  I'll look up the component after I finish cleaning.

That's no inductor, that's the voltage reference (LM399 is a classic precision oven-stabilized reference). It's supposed to be loose like that.

It sure has evolved from the massive red can oven in the earlier models! And woo! PCB! :P Mine's point-to-point on turrets stuck in a piece of copperless FR4-ish material.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on July 02, 2013, 03:42:49 am
I cleaned the front of mine with rubbing alcohol.  Put it on with a swab and let it soak into the stickers and then used a wide plastic alignment tool to scrape most of the paper and glue off.  then used more and wiping with a paper towel until they were clean.  Did not seem to bother the silk screened markings.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ddavidebor on July 02, 2013, 05:20:17 am
Naaa alcool don't work very well.

You should use a degreaser (for the kitchen, NOT a solvent based ones)

Il you want it like new you must remove everything from the front panel and clean it separately.

Next, you should use alcool to remove all the trace of the degreaser especially from glass surface.

Here i use chanteclair, is a  degrasser. It's so good that i buy it in 5L bottle.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ElektroQuark on July 02, 2013, 08:40:25 am
Some degreasers have NaOH as main active ingredient. NaOH eats aluminium, so beware, they can damage the panel finish.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on July 02, 2013, 11:25:32 am
Naaa alcool don't work very well.

You should use a degreaser (for the kitchen, NOT a solvent based ones)

Il you want it like new you must remove everything from the front panel and clean it separately.

Next, you should use alcool to remove all the trace of the degreaser especially from glass surface.

Here i use chanteclair, is a  degrasser. It's so good that i buy it in 5L bottle.

Why would you contradict a forum member that has cleaned more equipment than you have even seen?  :-//
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on July 02, 2013, 12:07:31 pm
Before/After
(http://www.stevenjohnson.com/web-pics/pd-before-after.jpg)

Remember to let the alcohol sit on the paper stickers to soften them.  Still watch out for any screened printing. It did OK with both my PD supplies but depending on manufacturer it could still do damage to the print.  Again, something soft plastic helps scrape off the goop without scratching the panel.

Actually sticker and label glue is not usually as bad as smoke residue.  Some of the early test equipment is so bad the panels have to be removed and soaked.  Bakelite panels and cases can be cleaned and polished using mag wheel cleaner you get at an auto supply but it removes any printing.  I would not use it on brushed metal panels though.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on July 02, 2013, 12:21:09 pm
I have found Toluene and Xylene especially effective on sticker goo.  "Goof off" and "Goo gone" are two that are readily available in the US with same or similar active ingredients. These will usualy totaly liquify the adhesives right through the stickers if the stickers are paper/pourous. If the stickers are non pourous then you need to keep a "wet front" on one edge as you gradualy peel the sticker up.  As with most things the magic sponges will enhance the cleaning action.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nukie on July 02, 2013, 11:30:47 pm
LM399 in a power supply!!! 8)

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on July 03, 2013, 01:23:35 am
Has anybody tried taking apart the rotary switches? I'd like to clean the contacts on the other right knob on my 5020. They are showing their age a bit...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SLJ on July 03, 2013, 03:13:41 am
Has anybody tried taking apart the rotary switches? I'd like to clean the contacts on the other right knob on my 5020. They are showing their age a bit...

See page 16.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on July 03, 2013, 05:07:15 am
Has anybody tried taking apart the rotary switches? I'd like to clean the contacts on the other right knob on my 5020. They are showing their age a bit...

See page 16.
Nobody seems to have tried, hence my question.

On a side note - anybody have a *clean* scan of the schematics for the 2020 or 5020? The only ones out there seem to be pretty much unreadable.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on December 18, 2013, 01:54:31 am
I'm pretty sure that this thread was to blame, but here they are, and are my two only power supplies that I use every night on the bench:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on December 18, 2013, 01:59:09 am
Glad we could help :D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on December 18, 2013, 02:40:50 am
I'm pretty sure that this thread was to blame, but here they are, and are my two only power supplies that I use every night on the bench:

Is that a 2225 above the 6050's?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on December 18, 2013, 06:37:07 am
I have noticed PD supplies going cheaply recently. Probably because this thread hadn't been bumped up for a while. There's a 5020 for $110 shipped right now. I love my 5020, but don't need another! Somebody should grab it!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on December 20, 2013, 06:00:43 pm
Its come a long way, but it has become more attractive, I think because of this and similar discussions.  As one of the early starters back when, my 5020 was ~$50 delivered, I have 4 of these types of supplies  :-+.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on March 01, 2014, 01:02:58 am
I'm pretty sure that this thread was to blame, but here they are, and are my two only power supplies that I use every night on the bench:

Is that a 2225 above the 6050's?

Yes sir it is!  I hold Dave responsible, but honestly, I am super super glad I started with the 2225... learned a lot about what all the controls are actually doing!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on March 01, 2014, 01:24:49 am
I'm pretty sure that this thread was to blame, but here they are, and are my two only power supplies that I use every night on the bench:

Is that a 2225 above the 6050's?

Yes sir it is!  I hold Dave responsible, but honestly, I am super super glad I started with the 2225... learned a lot about what all the controls are actually doing!

LOL! I love my 2225. 500uV/div is impossible to find in another analog scope.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on March 01, 2014, 01:32:14 am
LOL! I love my 2225. 500uV/div is impossible to find in another analog scope.

You missed post #142 of this thread here (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg169147/#msg169147)   10µV/div is possible ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on March 01, 2014, 03:19:49 am
LOL! I love my 2225. 500uV/div is impossible to find in another analog scope.

You missed post #142 of this thread here (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg169147/#msg169147)   10µV/div is possible ;D
LOL! Yeah... maybe I should say VERY difficult... unless you happen upon a $35 diff amp and the mainframe to plug it into.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on March 01, 2014, 02:22:45 pm
LOL! I love my 2225. 500uV/div is impossible to find in another analog scope.
I often end up recommending or at least mentioning the Tektronix 2225 just because its 500uV per division input sensitivity.

The rarer but available Tektronix 2211 and 2214 combination analog and digital storage oscilloscopes also go down to 500uV per division.

You missed post #142 of this thread here (https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/msg169147/#msg169147)   10µV/div is possible ;D
While I have a couple of 7A22 plug-ins for my 7000 series mainframes, they are tricky to use at their most sensitive setting because their drift and low frequency noise performance is not as good as it could be.  There is an equivalent plug-in for their 5000 series oscilloscope mainframes and also the stand alone AM502 which can be used with any oscilloscope.

You can get better results with a dedicated low noise amplifier but there is an easier way; if you have a DVM with the required sensitivity and noise performance that will operate in sample mode, then the standard deviation of the DC voltage readings is a good way to measure the RMS value of the low frequency noise.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on March 01, 2014, 02:44:20 pm
And I forgot about the 7A15A plug-in for the 7000 series which goes down to 500uV per division and is single ended.  They are more common, less expensive, and easier to maintain than the 7A22.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on March 01, 2014, 02:50:30 pm
What is the relationship of sample rate to what frequency band the SD represents.  Example my 8846A at 6.5 digits would give a 6Hz sample rate. Would that mean the highest frequency component I am measuring is 0.6Hz (nyquist)?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on March 01, 2014, 04:02:05 pm
The low frequency limit depends on the total period of time over which you gather samples.  You will not see noise down to 0.1 Hz if you only collect samples for a period of 1 second.

The high frequency limit depends on the sampling gate duration and not the sampling rate.  In practice for a high resolution DC voltmeter, this will be some multiple of the line frequency resulting in a best case first null at 50 or 60 Hz and the frequency response will follow the sinc function.  The bandwidth is limited by the sampling gate width and not the sampling rate in this case.  Sampling RF voltmeters work this way and while aliasing occurs, the histogram of the signal is the same so the peak to peak, RMS, and average measurements are the same.  Conveniently the standard deviation is equal the AC RMS value.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 18, 2014, 06:01:09 pm
Yet another way to measure ripple at specific frequencies in these two posts (https://www.eevblog.com/forum/testgear/hp-3410a-ac-microvoltmeter-restoration/msg446308/#msg446308)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: iampoor on September 20, 2014, 10:26:42 pm
Are there any power designs supplys with a negative rail? I would love a nice high precision +/- supply.  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: PedroDaGr8 on September 20, 2014, 11:37:08 pm
Are there any power designs supplys with a negative rail? I would love a nice high precision +/- supply.  :-+

Two HP Precision 611x series can be wired to run in series mode. According to the manual, simply ground the "center tap"  to create a +/- precision supply.

Sent from my LGLS990 using Tapatalk

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on September 22, 2014, 11:07:44 am
Are there any power designs supplys with a negative rail? I would love a nice high precision +/- supply.  :-+

Power supplies are generally not precision devices but many include two symmetrical outputs which may be connected in series or parallel.  More common are bipolar power supplies which may include tracking like the HP 6236, Power Designs TP325, TP340, and TP343, and the Tektronix PS503.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: albert22 on September 26, 2014, 05:37:33 pm
Hi. I have been trying to understand how the decade switch works on the PD 2005 schematics. It is common to use 1,2,2,5 values for a decade but I cannot figure out what is the function of the 4.7, 6.8, 27  resistors.  Also, it seems that in some cases they are paralleling .1% ww resistors with 10% carbon ones.
Please. Can someone explain this?
Thanks and Regards
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 30, 2014, 11:30:20 am
Anyone have a 2010 or 2020 they're looking to get rid of? eBay has been pretty dry lately. (I've got an offer in on a 2005.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 01, 2014, 01:33:46 am
Just after posting the above I found a 2020B buried away on eBay! Snagged it for $75, shipped. The seller says it goes into overload as soon as it’s switched on; I’m thinking it could be as simple as one of the sense or remote straps not being connected on the back, but we’ll see. Either way, it’ll be fun to fix!

I also grabbed a 2005A for $65+Shipping. Seller says it works fine. Turns out he had two available and listed both as 2005P; in actuality one is a 2005A and the other (with non-working lamps) is a 2005P. The P model is the Remote Programmable version, which appears to only have controls on the front for setting a voltage and current limit plus zeroing. You can see the 2005P in the first picture but the 2005A in the second and third. So if anyone wants a 2005P at a decent price, here you go: http://r.ebay.com/tD7RwT (http://r.ebay.com/tD7RwT)

(The 2005A only allows remote voltage setting, the 2005P can set current and voltage remotely, like the 2020Bs.)

By the way, I’m working on a simple USB adapter for the 2020B/2005P to allow remote control of voltage/current via SCPI commands over serial. If anyone is interested or has ideas, let me know!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 02:12:35 am
By the way, I’m working on a simple USB adapter for the 2020B/2005P to allow remote control of voltage/current via SCPI commands over serial. If anyone is interested or has ideas, let me know!

Neat!  I have a project in the back of the draw to do something similar for the 6050, 6050C and 6050D.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 01, 2014, 03:57:49 am
By the way, I’m working on a simple USB adapter for the 2020B/2005P to allow remote control of voltage/current via SCPI commands over serial. If anyone is interested or has ideas, let me know!

Neat!  I have a project in the back of the draw to do something similar for the 6050, 6050C and 6050D.

Do those use the same 1k/V and 1k/A formula as the 20xx Series?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 01, 2014, 11:24:21 am
You may want to consider making it also work on the very popular HP611X series supplies.
manual link here (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&sqi=2&ved=0CDMQFjAC&url=http%3A%2F%2Fcp.literature.agilent.com%2Flitweb%2Fpdf%2F5950-5976.pdf&ei=weMrVISxNc-LyAS1-YLYBg&usg=AFQjCNHzO7tE10zs9vfF6UeaTMZzHmyBig&sig2=XH6NVPtrVcDSgU0ivb-tpQ&bvm=bv.76477589,d.aWw) - remote programming starts at section 3-23
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 12:57:30 pm
By the way, I’m working on a simple USB adapter for the 2020B/2005P to allow remote control of voltage/current via SCPI commands over serial. If anyone is interested or has ideas, let me know!

Neat!  I have a project in the back of the draw to do something similar for the 6050, 6050C and 6050D.

Do those use the same 1k/V and 1k/A formula as the 20xx Series?

I wish!  The principle is the same, a resistance-controlled feedback loop, but the ratios are different. In fact, for the 6050 (which has two voltage ranges, 0-6 and 0-60) the same remote programming loop has two different ratios depending on the selected voltage range.

Originally I was going to use some sort of e-Pot to control the voltage, but I realized quickly that you need an e-pot that can handle 0-60V (for the supplies I have) so that was out due to cost. The other option (which is sorta where I left it) was to use a MOSFET in its linear range as a voltage controlled resistor. But that still requires me learning more on how to do that :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: linux-works on October 01, 2014, 01:02:42 pm
here's an idea, maybe.

one of my projects that I designed was a relay attenuator (for audio use).  its a little like a pot but uses relays and resistors.  put voltage in and get a percent of it, out.  on my board, its 8 relays at half db steps from -128db to 0 db (again, this was meant for audio use as a cpu based stepped atten).  the resistors could be changed to be more linear instead of log and this could be a nice voltage divider that is arduino controlled.

then, you just need a clean stable voltage source and put that on the input of the atten board.

the pdi boxes, iirc, are voltage controlled so having a programmable voltage send to the rear panel for control would do the trick.

search for 'lcduino' and 'delta1' (amb.org is the site) and you'll see the project I'm referring to.

see if that might be a way forward for this.  you can change the step size and range just via the series and parallel resistors that you pick.

then, you simply talk to the arduino over serial and it will translate to the relay bank values.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 01:13:43 pm
@linux-works:

I've looked at the remote control circuit, and it seems that there is a MAX_RANGE voltage (so say 60V in the case of my 6050C or D) that is placed across a pot. There is a constant current circuit that feeds this pot and what you end up with is the voltage drop across the pot is the set output voltage of the supply. I will see if I can grab a picture of the circuit and post it. Perhaps in a new thread :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: linux-works on October 01, 2014, 02:58:45 pm
its just a voltage programmed PSU.  so anything that can let you program in a control voltage (not much current is needed, of course) will let you remotely control the PDI psu.

I've been able to put 60v easily into my resistor/relay atten board and it works fine.  it has no active parts in the way (no pre or post buffers) and so its fully passive and can take even 100v if you really want to.  to test 127db of atten, I did have to put 60v thru it just to see the few microvolts coming out the other end.

the only thing that would need changing is the Rs and Rp values to make it linear instead of log (audio).

you would hear relay clacking as you change the control voltage, but its not very loud if its inside a box and those are telecom relays, not big loud power ones, so they don't make too much of a bang-bang sound.  in my circuit, it uses latching relays and so the voltage only happens (across their coils) for a few ms and then the magnetics hold the relay in A or B position until you change it.  that's kind of neat in that the circuit has a 'memory' even when powered down.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 01, 2014, 03:11:57 pm
That's over complicating for this use, I think. Here's my plan:

Grab a 60V linear MOSFET or transistor and simply hook the source and drain up to the RV lines. Then use an OpAmp with the output hooked to the gate and the non-inverting input hooked to the PSU output. Then you can use a DAC or PWM signal on the inverting input to control the whole thing. (You'll also have to either attenuate the PSU output or boost the DAC's output for feeding the main OpAmp.)

I'll draw the circuit up later.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 03:24:27 pm
That's over complicating for this use, I think. Here's my plan:

Grab a 60V linear MOSFET or transistor and simply hook the source and drain up to the RV lines. Then use an OpAmp with the output hooked to the gate and the non-inverting input hooked to the PSU output. Then you can use a DAC or PWM signal on the inverting input to control the whole thing. (You'll also have to either attenuate the PSU output or boost the DAC's output for feeding the main OpAmp.)

I'll draw the circuit up later.


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Hmm, seems simple enough. I might try that out tonight. However, did you reverse your inverting/non-inverting connections for the Op-Amp? I.e. feed the non-inverting with the smoothed PWM signal and tie the inverting input to the PSU output).  But I like it!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 01, 2014, 03:36:08 pm
That's over complicating for this use, I think. Here's my plan:

Grab a 60V linear MOSFET or transistor and simply hook the source and drain up to the RV lines. Then use an OpAmp with the output hooked to the gate and the non-inverting input hooked to the PSU output. Then you can use a DAC or PWM signal on the inverting input to control the whole thing. (You'll also have to either attenuate the PSU output or boost the DAC's output for feeding the main OpAmp.)

I'll draw the circuit up later.


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Have you not just cut out all of the original stability of the supply and taken that task on in your circuit?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 01, 2014, 03:40:22 pm
We're just using the FET as a variable resistor essentially. So I don't see how, as that's how the remote voltage works on the 20xx series. (You're bypassing the internal voltage knob resistors with an external resistor.) So I'd personally use a fast, low noise, low drift OpAmp.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 01, 2014, 04:18:52 pm
I am no EE but I think as soon as you use the PS output to drive your op amp you have two control loops.  If you supply a fixed voltage or resistance the control loop is only the original PS.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 05:05:02 pm
I seem to remember reading in the operating manual (+theory of operation) that any noise introduced onto the remote programming line will be present on the PSU's outputs. The idea was that you would use shielded cables + "shmick" pots to have near or equal noise specs at the output. But I could be very wrong about that. I need to consult The Fine Manual.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 01, 2014, 09:18:41 pm

I seem to remember reading in the operating manual (+theory of operation) that any noise introduced onto the remote programming line will be present on the PSU's outputs. The idea was that you would use shielded cables + "shmick" pots to have near or equal noise specs at the output. But I could be very wrong about that. I need to consult The Fine Manual.

Yup, this is correct. They also recommend using Make-before-Break relays if you're switching in resistors, because when it goes open circuit it causes a loss of regulation which would induce transients into your output.

And nobody wants their PSU to be like Portland.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 01, 2014, 10:03:36 pm
Yup, this is correct. They also recommend using Make-before-Break relays if you're switching in resistors, because when it goes open circuit it causes a loss of regulation which would induce transients into your output.

Actually I believe it's "worse" than that... when the control path goes open circuit, the crowbar kicks and you need to power cycle the supply. Not damaging, but it would ruin your day.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 04:26:03 am
So, my 2020B came in today… Of course the seller packed it extremely well!

(http://img.timb.us/PD2020B_1.jpg)

Look at the layers and layers of bubble wrap! Of course, you only need bubble wrap on the top, right? |O

(http://img.timb.us/PD2020B_2.jpg)

Unfortunately, despite the expert packing, it seems the fuse holder was broken in transit.

(http://img.timb.us/PD2020B_3.jpg)

Not enough to glue it back together. I also shocked the shit out of myself after plugging it in when I went to move it, because I forgot about the exposed fuse. I’ll just replace it with a modern holder.

So, upon turning it on, it does go into overload like the seller stated. I measured 40VDC on the output. Upon checking the back, I noticed there were no straps between the Sense and Output terminals, so I added some wires.

(http://img.timb.us/PD2020B_7.jpg)

Despite this, it still was outputting 40 volts. I pulled out the current limit knob and a puff of magic smoke came out the top! I opened the bottom cover and the internal fuse was blown. It also appears that R18 is deformed, so I’m thinking that’s what was burning (it smells like it).

(http://img.timb.us/PD2020B_6.jpg)

So now I’m going to review the schematics and do some tracing. Any recommendations for some things I should check for?

Finally, here’s a nice picture of the entire board. Other than R18, everything else seems in good shape.

(http://img.timb.us/PD2020B_5.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 04, 2014, 12:04:04 pm
So I threw together the circuit you were describing timb, and yes, it works great! :D  I tuned it to use a control voltage of 0-6V for the full 60V range (and 0-0.6V for the 6V range).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 04, 2014, 12:21:27 pm
Also, @timb: right above (in the pictures you posted) the burnt out resistor, it looks like there is a fuse holder. There should be a fuse in there (if there wasn't one when you got it).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 01:57:15 pm
Awesome, good to hear that circuit works! And yeah, there was a fuse there. It blew when the smoke came out.

Oddly enough that resistor measures fine! I guess the coating just melted. (Still might replace both.)

Can anyone with a 2020B measure the diode drop of Q5, Q6 and Q7 for me? (The transistors mounted to the frame of the case.)

I'm getting a drop of 0.08V on Q6 & Q7, but I'm measuring in circuit so not sure if that's the cause or not.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 04, 2014, 02:00:49 pm
One of them is shorted then.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 02:10:56 pm

One of them is shorted then.

Damn, was afraid of that. They're unabtanium, too. I can't find them in any transistor cross reference or even a data sheet online. They're MS1700G's.

Hmmm, looking at the manual, the C500 used IR4230's and the 5020 used FS1700E's. Maybe I'll have more luck finding a match for those. They're both slightly higher spec models, so I imagine they'd work. I just need some basic specs to base a modern replacement on. (Outside of voltage and current.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on October 04, 2014, 02:25:04 pm
@timb: I found this, which might give you a hint to some of the specs of that transistor: http://www.parttarget.com/5961-01-094-7330_5961010947330_A65212.html/-DB6C6E5C-DADE-4CD7-8AA4-A5D858577F9D
 (http://www.parttarget.com/5961-01-094-7330_5961010947330_A65212.html/-DB6C6E5C-DADE-4CD7-8AA4-A5D858577F9D)

Good luck!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 04, 2014, 03:10:15 pm
It is a 2N1700, with a Motorola house coding and possibly a gain binning at production. If it is in a case that bolts to the chassis I actually have some............ Or at least one, and probably more in another box somewhere.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 05:10:29 pm
Yup, it's in a TO-2 package.

If you could check and see if you have two, I will send you some $$$ for shipping (plus whatever you want for the parts) along with my eternal love!

I assume the FS1700 is a Fairchild version of the 2N1700 as well? Curious why they used a different brand for the drive transistor...


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 04, 2014, 06:06:21 pm
One 2N1721 made 0780 necxt to me right now, with its little mount and nut, but no insulating kit though ( I probably lost those somewhere) and I will have to look to find a mate for it. Sad to say I cannot post it at present, unless you are willing to pay the $150 (Yes, got a quote Friday for another reason) fee to send via courier. SAPO is doing the best it can to prove I live in a fourth world country by escalating the 6 week strike to it being total. SA is making Detroit look good as a vacation spot, I might go there instead of going to relax in Syria or Iran, even Afghanistan looks good.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 09:18:59 pm
Damn dude, that sucks! Didn't know about the strike. I might be able to find a local replacement, if not I can wait!

It's weird, I can find 2n1700's on eBay, but they're all in TO-39 metal cans, not in the TO-3 package I have.

If I were to go with a more modern replacement, what parameter do I care about matching the most (assuming Vcb, Vce and Ic are all => the current unit)? I'm thinking Hfe, right?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 04, 2014, 09:43:49 pm
This looks promising: http://www.onsemi.com/pub_link/Collateral/2N5038-D.PDF (http://www.onsemi.com/pub_link/Collateral/2N5038-D.PDF)

Available on Mouser and eBay. What do you think?


Edit: Whoops! Wrong link. Found a suitable replacement anyway, see below.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 05, 2014, 04:45:15 am
Okay, I took out all three power transistors on the side of the case. It’s Q7 that’s shorted. The driver transistor (Q5) other pass transistor and both fine. I’ll most likely still replace them as a pair.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 05, 2014, 06:18:26 am
Put in a 2N3773 if it is a TO3 package, it will be a good replacement, and will work well within it's SOA limits as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 05, 2014, 07:19:21 am
Put in a 2N3773 if it is a TO3 package, it will be a good replacement, and will work well within it's SOA limits as well.

Ah yes, designed for linear operation. Looks pretty good! Found a bunch on eBay, so that’ll work out perfectly.

Okay, so like I said above, I pulled out all three power transistors and found the one with the short. To determine if that was the only problem, I popped the best fuse I had in (1A Slow-Blo) and hooked the driver transistor and the one pass transistor up via alligator clips:

(http://img.timb.us/PD2020B_A2.jpg)

And…

(http://img.timb.us/PD2020B_A1.jpg)

This thing is pretty much bang on, and I haven’t even touched the calibration pots.

(http://img.timb.us/PD2020B_A3.jpg)

So after testing R17 and R18 with makeshift Kelvin probes, they’re both exactly at 0.75Ohms, despite R18 being a bit deformed. However, after testing most of the resistors on the board, I did find R34 (the matched resistor to the LM399 reference) is measuring 3K~, instead of the marked 7.32K. Though, it doesn’t seem to be affecting accuracy? I might still replace it; unfortunately I can’t find any 0.3W replacements on Mouser (can only find 0.125W ones in-stock). So I may have to resort to using an SMD version with a little adapter board I’ve got laying around.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 05, 2014, 08:07:11 am
Use a higher wattage one instead, a 1W resistor will fit and will run cooler. Did you measure R34 with one lead unsoldered, you will get a false reading in circuit.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 05, 2014, 08:34:12 am
Ugh. Fucking site just ate my long reply…

Short version: Can’t find a 1W in that size at 0.1% but it might not be needed as I was testing in-circuit and see now there’s a 20k trim pot in parallel with the resistor, so that’s most likely what’s causing my reading. Since the unit seems to be working and in-spec, I may not even touch it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 05, 2014, 08:52:51 am
Working means leave well alone.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 05, 2014, 09:15:25 am
Also I just ordered a 5-pack of those transistors you linked and a fuse holder for the back. Now I just have to fix the panel meter (it sticks at the bottom, you have to give it a tap to get it to working), do some cleaning and she'll be good as new.

By the way, the seller gave me a $25 refund due to the packing and broken fuse holder.

Not a bad deal for $50+$10 in parts, eh?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 06, 2014, 10:17:00 pm
I might be addicted to these... I just picked up a 2005A for $50 and a 1025P (0-100VDC Precision Remote Programmable) for $35.

Also, it looks like the edgewise panel meter on the 2020B is shot. Unless I can find someone who has one from a parts unit, I'm going to need to get creative.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 06, 2014, 10:26:33 pm
Oh yeah, can anyone with a 2020B measure the voltage on the 10V/20V indicator lights for me? Thanks. =)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 06, 2014, 11:17:05 pm
Oh yeah, can anyone with a 2020B measure the voltage on the 10V/20V indicator lights for me? Thanks. =)


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125V according to the schematic
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: iampoor on October 07, 2014, 12:08:03 am


Do the Power designs power supplys have floating outputs that I could connect togeher to make a +/- supply? Im hinking somehing along the lines of a tw5005
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 07, 2014, 12:31:30 am


Do the Power designs power supplys have floating outputs that I could connect togeher to make a +/- supply? Im hinking somehing along the lines of a tw5005

Yes :D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 07, 2014, 01:01:43 am
Oh yeah, can anyone with a 2020B measure the voltage on the 10V/20V indicator lights for me? Thanks. =)


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125V according to the schematic



Yeah, I saw that, just wanted to verify as the schematic I have is a pretty poor quality scan, so it’s hard to read some of the digits. I wanted to make sure it wasn’t 12.5V!

I’m trying to figure out the best way to replace the bulbs with LEDs.



Do the Power designs power supplys have floating outputs that I could connect togeher to make a +/- supply? Im hinking somehing along the lines of a tw5005

Just make sure the DC- terminal isn’t strapped to the GND terminal on the front panel!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 07, 2014, 01:58:06 am
IMO save yourself a lot of trouble and just buy some new neon bulbs. I have replaced several on the PD units.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 07, 2014, 02:43:09 am
IMO save yourself a lot of trouble and just buy some new neon bulbs. I have replaced several on the PD units.

One of the assemblies was broke, so I'm going to have replace the holder anyway. I guess I could get a neon panel mount assembly.

Thinking about it though, there should be no reason an LED wouldn't work so long as you used a high enough wattage resistor. Right? (I found some Amber colored panel mount LEDs in my junk bin that fit perfect. I'd need nearly a 1W resistor though.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 07, 2014, 04:54:17 am
Would work with the original value resistor, just use a 1W unit. A hyperbright led would give more than enough light at low current. If the original neon lamps are dim then reverse them, they run on DC so only one electrode wears. Eventually the whole envelope gets sputtered and it stops working.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 09, 2014, 02:28:10 am
So my 2005 came in today. After plugging it in and turning it on, I began to smell something burning, but not in the normal Magic Smoke sense. This smelled like, I dunno, it reminded me of of those toy cap guns that took those rolls of paper caps? Anyway, I don’t *think* there was any smoke (lab labs weren’t all on, so hard to tell). I unplugged it right away, investigated a bit and turned it back on. The smell seemed to go away and the supply *seems* to work (after cleaning the switches), though I don’t think the oven light is ever turning off (hard to tell because it’s flickering, though I assume it would cycle on and off for seconds or minutes).

So I’m suspecting something went toasty in the oven. Thoughts?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: c4757p on October 09, 2014, 02:49:56 am
I began to smell something burning, but not in the normal Magic Smoke sense. This smelled like, I dunno, it reminded me of of those toy cap guns that took those rolls of paper caps?

Hmm - two very distinct smells that aren't quite the same: cap guns and overpowered potentiometers. But that was my first thought. Is there (or was there) anything shorting a potentiometer?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 09, 2014, 06:08:46 am

I began to smell something burning, but not in the normal Magic Smoke sense. This smelled like, I dunno, it reminded me of of those toy cap guns that took those rolls of paper caps?

Hmm - two very distinct smells that aren't quite the same: cap guns and overpowered potentiometers. But that was my first thought. Is there (or was there) anything shorting a potentiometer?

The back panel cal pot *may* have been shorted, I'm not 100% sure, because after  the whole smell incident I started trying to get the thing in regulation; apparently I didn't have the nut loose all the way or the securing nut wasn't tight and the whole pot was turning. At this point I had the bottom cover off anyway and noticed it. I'm not sure if it was already turned and I moved it more or what. But it could have been shorted on the bottom cover. (Though it seems to work fine.)

Should the oven be physically warm to the touch? It feels warmer than ambient, but no more so than surrounding parts. (I imagine it's well insulated so it shouldn't be.)

The oven light never going off does bother me a bit.

Oh, picture!

(http://tapatalk.imageshack.com/v2/14/10/08/e6d9a4e2f4599e0050d24c9a2a6ea192.jpg)

There's a modern cap soldered across one of the metal Sprague caps on the auxiliary board.

(http://tapatalk.imageshack.com/v2/14/10/08/fddfa1e76d1175353286adbd1716d76a.jpg)

Not sure what's up with that.

I did manage to find a date code on one of the Spragues; 17th Week, 1965


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 10, 2014, 08:23:18 am
The new transistors came in for my 2020B today. Hooked them up with some jumper wires for testing and they work perfectly! Thanks @SeanB, that 2N3773 was a good call. =D

Tonight I'll get them bolted and soldered on for real. I've even got some genuine Sil-Pads to mount them with! (Fuck Mica and the greasy horse it rode in on.)

Finally, I've designed a *really* cool replacement for the broken panel meter. I think you guys will really dig it.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on October 10, 2014, 01:02:01 pm
Does anyone know wher I can get a copy of the manual for the 2020 (not the 2020B). I have one that seems to start out reasonably stable, but after sometime, maybe correlated with the oven heating up, don't know yet, the stability drops and it starts to drift a bit. Hoping I can find a schematic and board layout for it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 10, 2014, 02:04:24 pm
Not sure what's up with that.

It is a common way to repair a circuit that has a worn out aluminum electrolytic capacitor without removing it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 10, 2014, 02:24:35 pm

Not sure what's up with that.

It is a common way to repair a circuit that has a worn out aluminum electrolytic capacitor without removing it.

Hmmm, yeah, I assumed it was there to repair the cap it was strapped over; but if you don't remove it (or at least one leg of it), how do you even test it to know if it's bad? (I've got a decent cheaper LCR meter that can do in-circuit testing, but it doesn't really work well on bulk caps unless they're out-of-circuit most if the time.)

Also, removing the bad cap prevents it from leaking on stuff.

It just seemed sort of lazy and bodgy to me.

But, perhaps it's more common than I knew and I just hadn't run into it much. =)

Either way, I think I'm going to replace all the AEs in the unit; I can't imagine they'd be very stable after 40 years?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 10, 2014, 02:48:21 pm
Not sure what's up with that.

It is a common way to repair a circuit that has a worn out aluminum electrolytic capacitor without removing it.

Hmmm, yeah, I assumed it was there to repair the cap it was strapped over; but if you don't remove it (or at least one leg of it), how do you even test it to know if it's bad? (I've got a decent cheaper LCR meter that can do in-circuit testing, but it doesn't really work well on bulk caps unless they're out-of-circuit most if the time.)

Testing is easy for a power supply input capacitor.  Just measure the ripple voltage.  If you know the load current, which you will in a power supply because you can set it, then a measurement of either the peak to peak ripple or the slope of the ripple can be used to determine the capacitance.

The general rule is 8200 microfarads per amp/volt assuming 60 Hz power and full wave rectification.

Quote
Also, removing the bad cap prevents it from leaking on stuff.

It just seemed sort of lazy and bodgy to me.

But, perhaps it's more common than I knew and I just hadn't run into it much. =)

I do not recommend the practice myself for the reasons you identify. :)  It is handy as a temporary measure and for testing though.

Quote
Either way, I think I'm going to replace all the AEs in the unit; I can't imagine they'd be very stable after 40 years?

I usually replace them all or at least all of the similar ones if one goes bad or has become marginal.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 10, 2014, 02:54:35 pm
Ahh yeah, totally didn't think of measuring the ripple on for the filtering caps; that's a great tip!

I'm also wondering about all the ceramic disc caps on this as well; I've heard tales of tin whiskers and such. 50 years (not 40 as I stated before; 1965 date code) is a long ass time! Half a decade...


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 10, 2014, 03:12:22 pm
I'm also wondering about all the ceramic disc caps on this as well; I've heard tales of tin whiskers and such. 50 years (not 40 as I stated before; 1965 date code) is a long ass time! Half a decade...

Ceramic capacitors tend to fail with a short which would be apparent.

Tin whiskers are unlikely unless pure tin plating or lead free solder was used.  In a power supply, there are a lot of areas where the currents are high enough that any whisker would vaporize anyway.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: macboy on October 10, 2014, 04:00:22 pm
...
So after testing R17 and R18 with makeshift Kelvin probes, they’re both exactly at 0.75Ohms, despite R18 being a bit deformed. However, after testing most of the resistors on the board, I did find R34 (the matched resistor to the LM399 reference) is measuring 3K~, instead of the marked 7.32K. Though, it doesn’t seem to be affecting accuracy? I might still replace it; unfortunately I can’t find any 0.3W replacements on Mouser (can only find 0.125W ones in-stock). So I may have to resort to using an SMD version with a little adapter board I’ve got laying around.
7.32 k can be made with 8.2 k || 68 k, both are E24 series.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 10, 2014, 08:11:38 pm
Anecdote on 2n3773's. I once needed a pair of replacement pro Electron devices ( can't remember exact part but it was a BDYxx series one) so put in an order with stores for 2. A month later I get a call from the head stores, asking how many I would need in the next decade. They were apparently a superseded part, and while the original manufacturer ( now part of the Airbus consortium) still had the masks and the process equipment, they would be a special order. Cost was $100 each, and there was a minimum order quantity of 10k units, with a 11 month lead time from confirmation and payment up front. I was asked if there was a replacement instead for them. So looked in the "transistor bible" and on the page in particular was listed 30 or so equivalents, among stem was the 2N3773 listed as "Improved specs". Checked in stores, and they were both there, in stock ( around 30k on hand) and available for us to order. Placed the order for 4 cases, as they would also replace 2N3055 transistors in any application as well.

When they arrived I used 2 as needed and stuck the rest in stock, looking like they would be a decade or more till finished. Little did I know that next month in would come the first of a line of Tower ferroresonant UPS units, which each either used 50 of them, or a $5k transistor brick. New batteries ( all 4 car batteries), 50 new transistors ( or scrap it if it blew the big silicon block and keep for spares) and run for a week with a 2 bar heater as load after repair. Some got a big chunk of heatsink with the transistors added as replacements. Horrid with the emitter sharing resistors being 10cm lengths of 0.5mm copper wire soldered to 24 emitters, and commoned on an insulated bolt. Transistor 25 was the driver for the darlington thus made.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 11, 2014, 09:16:37 am
Holy crap, that sounds like a Super Darlington! How big we're those UPS units? 4 car batteries, must have weighed a few hundred pounds between that and the heatsinks, right?

2020B Update:

(http://tapatalk.imageshack.com/v2/14/10/11/8f2289e15a7c9c0091cb617246cfaf56.jpg)

(http://tapatalk.imageshack.com/v2/14/10/11/714f3473f9474565b994b081feb7f06c.jpg)

Holds regulation perfectly (less than 90uV output ripple) and the voltage is spot on to +/-5uV, which is crazy good considering it came to me non-working and I haven't even touched the cal controls!

I'll leave you with 6.5 digits of pure sex:

(http://tapatalk.imageshack.com/v2/14/10/11/09fbfc2fc529bcfdc6ab5ee4682b8bad.jpg)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 11, 2014, 11:44:58 am
They were 2kVA minimum units, with moving involving either a forklift or a really strong trolley and 2 people minimum to lift onto the trolley. Around 200kg of steel alone, with another 10kg of copper, and the 2 1m long heatsinks as well inside.

Most faults had a similar symptom, no working and breakers tripped ( 63A DC bus breaker), and you would find 20 transistors minimum that had delidded themselves, or which had blown a hole in the lid. Plus the internal 80A fuse would also be blown. Most common cause was dead drivers on the main board, or dry joints there, or the PCB traces going open circuit, or all three and dead caps for good measure. They use 100uF 500VAC motor run caps on the output to filter the output, so had a low distortion real sine wave, at the expense of being also a room heater.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 11, 2014, 03:05:59 pm
I have a question about the 2N3773.

I have old data showing it with a minimum Ft of 200 kHz and the current On (Motorola) datasheet is consistent with that but the Central Semiconductor datasheet says 4.0 MHz and the STM datasheet does not say but does mention a planar process which implies 4.0 MHz instead of 200 kHz.

Is this like the situation with the 2N3055 where the original process used (epitaxial base) was slow but rugged and it was replaced with a newer one (planar) that was fast but had a smaller SOE?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 11, 2014, 03:47:41 pm
Yes planar is generally an order of magnitude faster, but if the die size is not shrunk then SOA would be pretty much the same, as it is a function of current density in the silicon. To meet the  label specs the device has to be equal or better than the JEDEC spec for the particular original manufacturers device. This often means the original device specs may be well exceeded in some areas, typically in voltage and current along with frequency specs, but it must meet the rest of the specs as well, and that includes SOA curves.

You can label a 2N3773 as a 2N3055, and it will comfortably pass any test aside from how the die looks. The other way around it does not work well.

As the devices in question are Motorola and packaged in the cheaper Motorola package, the higher value and military spec Motorola parts would be in a shaped plated KOVAR package with a dome top ultrasonically sealed to the base and with gold plated leads, they do fit the cost of the devices, low cost yet reliable. The remaining old device looks like it was made by Fairchild, who also did offshore assembly of US made dice.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 11, 2014, 04:06:32 pm
If you're talking about the parts in my picture, yeah, I had a wide range of choices for the 2N3773s; from 1980's RCA units to modern ST and ON versions. In the end, I went with the mid-90's Motorola parts because the price was right and the seller got me matching date codes (so I could try and get two as closely matched as possible).

The transistors I replaced were also Motorola brand, so it adds a bit of authenticity to the whole thing. =)

One thing I don't understand though... Why did PD specifically use a FS1700E for the driver and MS1700G's for the pass elements? They're both 2N1700's, right? I tested the good MS device and the FS; both have the same curve outputs on my tracer.

Seems weird they wouldn't just use all of one type.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 11, 2014, 05:38:43 pm
They might be the same device, but different gain binnings. Typically the power devices have a large gain spread, or they were selected for a particular binning for gain within a range at low and high current. with some power devices the gain difference with current can vary from typically 15 at 1A to 0.8 at 40A, and they are still in spec.

e might be binned for good low end gain and the G for good high current capability. In any case the new units will be much better just due to the later tighter process control.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 11, 2014, 07:06:04 pm
In the end, I went with the mid-90's Motorola parts because the price was right and the seller got me matching date codes (so I could try and get two as closely matched as possible).

I just buy a few extras and grade them myself.  I recently did this with 2N5886G transistors (80V 25A 200W 4MHz TO-3) and out of four, two matched to within a couple millivolts at the expected operating current.  The original design did not even use emitter ballasting on the parallel transistors so I added that as well when I repaired it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 11, 2014, 07:12:41 pm
A lot of power supplies use equal length emitter wiring to get some matching when running devices at levels where they use 2 or more but want the lower device temp from having more dies and heatsinks. Needs matched devices, preferably to within 5% at operating conditions, but often worked using just devices from the same batch and in the same shipped pack, as they likely did come from the same die and roughly the same area as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 11, 2014, 10:23:50 pm

In the end, I went with the mid-90's Motorola parts because the price was right and the seller got me matching date codes (so I could try and get two as closely matched as possible).

I just buy a few extras and grade them myself.  I recently did this with 2N5886G transistors (80V 25A 200W 4MHz TO-3) and out of four, two matched to within a couple millivolts at the expected operating current.  The original design did not even use emitter ballasting on the parallel transistors so I added that as well when I repaired it.

That's exactly what I did as well. I needed two, so bought four (with matching date codes to up my odds) and then used my cheap Chinese transistor tester to get the Hfe and base voltages, followed by a run through my homemade curve tracer to verify the current characteristics.

I ended up with two that were about a 1% match. 


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on October 12, 2014, 02:13:13 am
I just buy a few extras and grade them myself.  I recently did this with 2N5886G transistors (80V 25A 200W 4MHz TO-3) and out of four, two matched to within a couple millivolts at the expected operating current.  The original design did not even use emitter ballasting on the parallel transistors so I added that as well when I repaired it.

That's exactly what I did as well. I needed two, so bought four (with matching date codes to up my odds) and then used my cheap Chinese transistor tester to get the Hfe and base voltages, followed by a run through my homemade curve tracer to verify the current characteristics.

I ended up with two that were about a 1% match. 

A long time ago when I first matched power transistors for parallel operation, I tried a bunch of different methods but found the most cost effective was to tie the base to the collector and measure the forward voltage at a high current but below saturation.  About equally effective was measuring Vbe at the expected base current.  Both correlated well with hfe and produced good current sharing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 12, 2014, 07:37:16 am
Figure this one out... Earlier I was fiddling with the supply I just replaced the transistors on. I was testing out LEDs in place of neon bulbs. As I finished up, I was putting some LEDs back in a box when I saw (and heard) a huge spark emanate from the transistor area on the case! I though maybe a test lead had grounded against the case; everything seemed to still work fine.

A few hours later I was load testing the supply. After I was finished, I turned it off to let everything cool down. About 30 minutes later I come back, flip the switch and CRACK, another huge spark.

WTF? I did a continuity test on all the transistors, the isolation is fine.

There's no scorch marks anywhere and nothing smells.

I've yet to see it happen again, but two times makes me suspicious...


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 23, 2014, 12:24:00 am
So, it's been s bit since my last update on the 2020B! The issue in my last post was caused by a bit of liquid trapped under the Silpad (from the IPA I used to clean the contacts with after soldering).

My parts came in from Digi-Key yesterday, so I put everything in last night.

(http://tapatalk.imageshack.com/v2/14/10/22/4ea268b9bac6c76573a2d3791d0850ed.jpg)

(http://tapatalk.imageshack.com/v2/14/10/22/cf495fd728b1a9115e17f8bb7f20670a.jpg)

New banana jacks and neon lamps.

(http://tapatalk.imageshack.com/v2/14/10/22/6d393b61c282d43a5b1561edf9fad507.jpg)

(http://tapatalk.imageshack.com/v2/14/10/22/82b96a07f1127cb81e0aff11d45005bb.jpg)

(http://tapatalk.imageshack.com/v2/14/10/22/94e59c607cb3e3e5787fb41d7d905f01.jpg)

Plus a new fuse holder to replace the one that broke during shipping!

So, I button everything up, plug it in, flip the switch and...problems. =(

If I set it to 1V, I get 1.5xx, with the x being constantly drifting digits. Anything higher than about 3V and it jumps straight up to 28V. The 10-20V range puts the output to 32V. Strangely, even though it seems out of regulation, I can still manipulate the last three digits with the dials (though it drifts up fast).

I have no idea what could possibly be wrong. Last time I checked the unit (3 days ago) it was working fine. I've only replaced what I mentioned above.

Something I did notice, Q4 is getting way too hot; it's at the point of burning your finger if touched. This is the transistor that powers the LM399's heater I think. I checked the voltage across the LM399's Zener pins and I'm getting 7.0028 volts, so that's in spec.

I wonder if Q4 is shorted, or if the heater is shorted even? Hmm.

Thoughts?


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Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 23, 2014, 11:29:29 pm
Q4 is fine, so is the LM399's heater.

I started systematically checking voltages last night and finally ran across an issue!

The two inputs of the voltage regulation op-amp are at different voltages. This has to mean that either something in the driver path or feedback loop is broken.

Time to start buzzing out all the wires I think.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ElektroQuark on October 24, 2014, 07:13:58 am
Those little beautys are really entertaining.
I really enjoy this type of thread so, I hope you find the fault and plenty of research and photos be needed. I want to see them here  >:D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on October 24, 2014, 02:50:35 pm
I love Power Designs power supplies, and use them almost exclusively on my benches short of one HP supply.  I don't have one of the precision models (yet) but have several of the lower voltage/higher current and dual supplies along with one of their 10 V to 6 kV 20 mA high voltage supplies made at Power Designs Pacific in California, who made up to several hundred kV, several hundred pound monsters!   Although decidedly old-school, PD supplies are built like concrete and can take just about anything you could ever dish out to them.  The New York based company lasted in to the 1980's then just sort of dropped off the face of the planet one day, probably bought out by someone.   :(

-Mark-

I'll take apart and post some pictures of the 6 kV supply and post them soon.  You thought this little precision model was interesting.......  ;)


Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 24, 2014, 03:12:15 pm
So all the board to control wires seem fine. I started checking diodes (in-circuit) and found two that appear to be shorted. Hmmmm...

(http://img.timb.us/2020B_Sche.png)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on October 24, 2014, 11:38:35 pm
Those will read as shorted as they have jumpers across them at the back panel. Those protect the sense inputs.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 25, 2014, 02:53:51 am
Those will read as shorted as they have jumpers across them at the back panel. Those protect the sense inputs.

I’ve got those removed for testing, as I thought about that. It may be a bad cap after some more testing. But that wouldn’t cause the problems I’m seeing I don’t think. I wonder if it could be the Op-Amp? Hmmm, looks like the OP-05CP is equivalent to the uA741. Might grab one and see.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on October 25, 2014, 07:10:30 am
Those will read as shorted as they have jumpers across them at the back panel. Those protect the sense inputs.

I’ve got those removed for testing, as I thought about that. It may be a bad cap after some more testing. But that wouldn’t cause the problems I’m seeing I don’t think. I wonder if it could be the Op-Amp? Hmmm, looks like the OP-05CP is equivalent to the uA741. Might grab one and see.

Did you check Q3?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 25, 2014, 07:28:17 am

Those will read as shorted as they have jumpers across them at the back panel. Those protect the sense inputs.

I’ve got those removed for testing, as I thought about that. It may be a bad cap after some more testing. But that wouldn’t cause the problems I’m seeing I don’t think. I wonder if it could be the Op-Amp? Hmmm, looks like the OP-05CP is equivalent to the uA741. Might grab one and see.

Did you check Q3?

It's on my short list. It's not shorted, but it could still be bad. I'll have to take it out to test it, but I need to fix my cheap Chinese component tester first, as it shit the bed the other day. (I may have blown the ATmega after hooking it to a 9000uF cap that wasn't discharged by I clipped it to a blue-yellow wire instead of a yellow-blue wire in something I was testing...)

Weird thing is, the supply semi-works at the 1V setting (I get 1.5V out), but once you pass 2V or so you basically lose regulation and get 28V. On the 10-20V setting you get 32V.

I guess Q3 could be saturating very early or something? I just don't get what could have killed it. It worked fine the other day! It hasn't even been plugged in!

And Sean, you're right, I double checked and I had the RV/RC jumpers removed (when buzzing out some wires) and thought they were the sense jumpers when I looked last night. (The supply is upside down right now, easy 5AM mistake to make I suppose.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on October 25, 2014, 07:33:44 am

Those will read as shorted as they have jumpers across them at the back panel. Those protect the sense inputs.

I’ve got those removed for testing, as I thought about that. It may be a bad cap after some more testing. But that wouldn’t cause the problems I’m seeing I don’t think. I wonder if it could be the Op-Amp? Hmmm, looks like the OP-05CP is equivalent to the uA741. Might grab one and see.

Did you check Q3?

It's on my short list. It's not shorted, but it could still be bad. I'll have to take it out to test it, but I need to fix my cheap Chinese component tester first, as it shit the bed the other day. (I may have blown the ATmega after hooking it to a 9000uF cap that wasn't discharged by I clipped it to a blue-yellow wire instead of a yellow-blue wire in something I was testing...)

Weird thing is, the supply semi-works at the 1V setting (I get 1.5V out), but once you pass 2V or so you basically lose regulation and get 28V. On the 10-20V setting you get 32V.

I guess Q3 could be saturating very early or something? I just don't get what could have killed it. It worked fine the other day! It hasn't even been plugged in!

And Sean, you're right, I double checked and I had the RV/RC jumpers removed (when buzzing out some wires) and thought they were the sense jumpers when I looked last night. (The supply is upside down right now, easy 5AM mistake to make I suppose.)


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Check those two protection diodes on the op-amp input too.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 26, 2014, 12:39:48 pm
Checked em, they seem fine as well.

Okay, so none of this makes any sense to me at all.

When I first turn on the supply, here’s what I’m seeing:

0V Position: 0.4V
1V Position: 1.4V
2V Position: 27.xV
3V Position: 28.xV
4V Position: 29.xV
(Etc.)

Now, if I turn the dial back to 0V, I get 8-9V on the output and Q4 (the LM399H heater transistor) gets hot as shit. If I pull the current set knob and push it back in, the output settles back at 0.4V and Q4 gets cool again.

Now, here’s something interesting for you: If I hook the reference (ground) lead of my scope to the negative terminal of C4 (without even having the probe connected to anything) the voltage goes down by a large margin (1V is 1.03V, 2V is 2.08V, 3V is 3.22V 4V is 4.4V, 5V is 5.6V and at 9V is starts out around 10V then drifts up to 12V after a few seconds).

Here’s a few scope captures from the Voltage Regulation Op-Amp:

(http://img.timb.us/U2-Neg-6V.PNG)
Inverting Input, 6V Output Selected

(http://img.timb.us/U2-Pos-6V.PNG)
Non-Inverting Input, 6V Output Selected

(http://img.timb.us/U2-Out-6V.PNG)
Output Pin, 6V Output Selected

(http://img.timb.us/U2-Pos-1V.PNG)
Non-Inverting Input, 1V Output Selected

(http://img.timb.us/U2-Out-1V.PNG)
Output Pin, 1V Output Selected

I’m stopping for the night as I’m getting tired (and frustrated) and don’t want to miss something or make a mistake.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 26, 2014, 12:52:29 pm
The readings you listed imply problems in the Voltage setting resistors and swithches. I suggest setting up the PS for external resistance control as a test. This will eliminate possible problems in the resistors and switches in the unit. You need know good resistances to see what the rest of the circuitry is doing.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 26, 2014, 01:18:44 pm
One of the first things I tried. 1k ohms gives exactly the same result as if the unit was switched to 1V (1.4V).

The unit worked fine a week ago and I never touched the switches aside from cleaning them with DeoxIT. I've also measured out most of the individual resistors with kelvin clips and they're spot on.

(In the numbers I gave above, I forgot to add 0V is 0.4V. Last time the unit was working, it was 0.000xxxV, so that indicates a problem outside of the switches, right?)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on October 26, 2014, 01:41:30 pm
(In the numbers I gave above, I forgot to add 0V is 0.4V. Last time the unit was working, it was 0.000xxxV, so that indicates a problem outside of the switches, right?)

Sounds like it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 26, 2014, 01:44:52 pm
I've got replacement OpAmps on the way. In the mean time I'm just going to start unsoldering one leg of everything until I find something broken I guess... Maybe start with the transistors, then diodes, then caps?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on October 27, 2014, 05:34:25 pm
This one is baffling. It almost sounds like the behavior you see when the input to something is floating.

BTW: Check out this beautiful 2010 rebuild on eBay. I especially like the power cord mod he did.

http://www.ebay.com/itm/Power-Designs-2010-Precision-Power-Supply-Unique-/111493092318 (http://www.ebay.com/itm/Power-Designs-2010-Precision-Power-Supply-Unique-/111493092318)

The seller says he's here on EEVBlog frequently, so for all I know it might be one of you guys on the thread here. I hope he gets what he's asking for it, but I suspect the market of potential buyers is too small.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 27, 2014, 09:33:46 pm
Wow, very nice looking! A bit too pricey I think IMHO though.

And yeah, it is baffling. I almost suspect a ground issue or something. (Judging by the fact that when I connect the ground lead from my scope probe to the negative side of C3 things get better; it also happens if I touch the case of Q1.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 28, 2014, 03:34:27 am
So I tested a bunch more stuff this afternoon (out of circuit), still nothing. Then I ran into a new problem! I had a jumper wire attached to the DC- terminal and it accidentally touched the case of Q1, which caused a spark. Now the thing is completely out of regulation, though the current control still works; pulling it out brings it to 0V without heating up the power transistor resistors (which would happen if Q5, Q6 or Q7 were damaged like when I first got the unit). So this really makes me think there’s an issue with the regulation Op-Amp (U2). Somehow that short-circuit killed it maybe? I replaced Q1 with a 2N3773, but no change, still out of regulation. |O

(http://img.timb.us/2020B_Sch_2.png)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 28, 2014, 06:53:14 am
Ding Ding Ding! Found a bad component! VR3 is completely shorted. Now, I’m not sure if this happened with the short circuit I described above, or was the cause of all the problems to begin with. Hopefully I’ve got a suitable replacement.

(http://img.timb.us/2020B_Sch_4.png)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 28, 2014, 11:56:27 pm
So, my fourth precision supply just arrived; another eBay steal. This is a mint condition Model 1025P Remote Programming Precision Power Source, 0-100VDC @ 0-250mA.

It was apparently US Government surplus, based on the front panel sticker. It almost looks like the thing was never used; aside from a small crack on the meter and a scuff on the top cover. The neon lamps are also OEM original and still work with ZERO flicker, which leads me to believe this thing was rarely even plugged in! (The oven lamp would always remain on.)

Speaking of the oven, it heats up perfectly and the thermostat works! I haven’t hooked a programming resistance up yet, but by using the Voltage Limit control on the front, I can get it to go through the full voltage and current range without issues. I had originally bought this as a parts unit to fix my 2005A, but since it’s in such good condition I may end up making my own custom front panel using some nice ganged switches and low PPM resistors; or I could make a small board with relays that sits inside for remote control. Hmmmm….

By the way, if anyone has a 1025/1025P manual, let me know!

If anyone wants to know the date: 1967

(http://img.timb.us/PD1025P_1.jpg)
Overview

(http://img.timb.us/PD1025P_2.jpg)
Inside the Supply

(http://img.timb.us/PD1025P_3.jpg)
Back of the Front Panel

(http://img.timb.us/PD1025P_4.jpg)
Front Panel

(http://img.timb.us/PD1025P_5.jpg)
Bottom Side
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on October 29, 2014, 02:35:01 pm
Neat  :)  In the mid 60's where just about every big player in the game was well in to mass produced wave soldered PC boards, PD continued to build all their power supplies one by one, by hand.  This continued for the most part right to their very end, and they are always a joy to look at inside.  I have yet to buy a used PD supply that didn't work perfectly right from the get go, and have never done any repairs to the several I have.  The precision models had a little more complexity to them, this is likely why many of them you come across at auction need some repair. 

-Mark-


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 29, 2014, 06:51:25 pm
Yeah, of my 4 units, one had a bad thermostat (understandable when you consider the oven ran 24/7 even with the unit off and that it's mechanical), one had a bad heating cool and the last one had a bad power transistor.

It seems like in the early 70's they went from turret boards to hand soldered single sided copper clad boards.

The green mask on the 2005A is sweet looking and I love the orange color of the 2020B!


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on October 29, 2014, 08:46:11 pm
Even with the copper clad printed boards in the later PD supplies, they were laid out like fine artwork- you could put them in a frame and hang them on the wall  :D 

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 29, 2014, 09:28:53 pm
Does anyone have info on what happened to the company? Back in the day, there was three High End power supply companies in NY, including PD, Lambda and one other name I can't remember. Lambda got bought out and the other one is still going independently.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 30, 2014, 07:31:18 am
Damn, this 1025P is pretty amazing. I’m measuring about 500uV stability (6.5 digits with an HP3456A) at 100V! I’ve got an external precision 100k resistor hooked through some cheap ass alligator leads that are twisted together. It goes from 99.9996 to 100.0001 when the heater clicks off and vice versa when it comes on. I’ve had it running for 24 hours solid now and measured only 300uV drift, which is better than the stated accuracy specs! Not bad for a piece of kit made of all discrete components produced in 1967…
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on October 30, 2014, 02:41:28 pm
It's almost scary how stable and accurate they can be.  The later PD precision supplies have the LM399A reference, which is the same zener reference used in the HP 3455A, 3456A, and 3457A multimeters, so as long as the precision resistors in the supply don't drift, they should remain every bit as stable as those 6.5 digit meters. 

I haven’t figured out the whole story, but the original PD company was more than likely bought out.  It isn’t hard to notice that the quality of Power Designs small precision bench supplies went downhill dramatically with models like the 2040A and 1001A.  These were encased in cheap ABS plastic cabinets and had meters, knobs, and binding posts that were, well, horrible to put it lightly.  They also used a, “dicky,” as Mr. Jones would put it, plastic thumb-button assembly to select the output voltage.  This led me to think there was no way the original PD company would put anything like that on the market, because it was in such stark contrast to anything they made in the past.  Looking at the manuals for these later PD supplies, the company is no longer in NY or CA, but listed at 14 Commerce St, Danbury CT- most likely the address of the new owner, thankfully no longer in business making this sort of garbage. They obviously lacked the superb metal working capabilities or any concern to retain the type of quality of the original PD power supplies.

-Mark-
   

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on October 31, 2014, 07:15:47 pm
What do you guys think about designing a replacement for the internals of these supplies? I am thinking of:

- Replacement PCB using an LM399A and other modern parts. Op-amps instead of transistors except for the output drive stage.
- LEDs instead of lamps for indicators
- Reuse the voltage and other switches, transformer, and the chassis.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on October 31, 2014, 10:46:29 pm
It's doable for sure. I've been thinking the same thing. Basically you could replicate the 2020B design. Use the existing TO-3 pass transistors. Maybe even replace them with 2N3773's. Hmmm. Maybe a joint project?

That would be a lot better time spent than me re-designing the 2005A amplifier oven. Don't you think?

Edit: Though I might still do the 2005A Amplifier.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 01, 2014, 11:18:03 am
Okay. I'm getting pissed now. I replaced VR3 on my 2020B. Along with EVERY FUCKING TRANSISTOR AND ELECTROLYTIC CAPACITOR ON THE FUCKING FUCKER. PLUS U1 and U2.

Same exact shit as before. (I guess I had fried VR3 when I shorted the body of Q1 to ground.)

Not only that, but despite being pin for pin compatible and the specs being the same, the u741 won't replace the CP02-whatever OpAmp. So I've got to locate some NOS on eBay to see if that's my issue.

I'm at a loss for what to do if that doesn't work. It has to be in the feedback loop there somewhere.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 01, 2014, 02:53:00 pm
There is another 2020B up on eBay right now. He claims it is working, but based on his listing I am skeptical. Seller might accept a lowball offer if you want to use it for parts or to compare voltages at different points in the cct
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 01, 2014, 04:53:36 pm
What do you guys think about designing a replacement for the internals of these supplies? I am thinking of:

- Replacement PCB using ... Op-amps instead of transistors except for the output drive stage.

This is not difficult to do but only the input stages of the error amplifiers matter.  An alternative to replacing them is to use operational amplifiers to correct their offset and low frequency noise and drift.

That would be a lot better time spent than me re-designing the 2005A amplifier oven. Don't you think?

Edit: Though I might still do the 2005A Amplifier.

The 2005A design shows that Power Designs used a dual transistor as the error amplifier and stuck it into the oven to do these very things.  Improve the error amplifier and change the reference and the oven can be left out.

Not only that, but despite being pin for pin compatible and the specs being the same, the u741 won't replace the CP02-whatever OpAmp. So I've got to locate some NOS on eBay to see if that's my issue.

U2 is an Analog Devices OP-05 which is *not* directly replaceable with a 741 unless the nulling circuit which Power Designs used is removed or changed.  The OP-05 specifications are significantly better than the 741 specifications in all respects.  The way I remember it, the OP-05 is an OP-07 without the offset voltage trimming done during production so the OP-07 is a direct and superior replacement.  The later improved replacements for the OP-07 like the OP-77, OP-177, and OP-1177 should also work without changes but the OP-07 is inexpensive.

Other alternatives include the LT1001 and LT1097 but the OP-07 is probably the least expensive option with the same or better performance as the original OP-05.  If you want to use a 741, then disconnect the nulling circuit.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on November 01, 2014, 05:24:01 pm
Okay. I'm getting pissed now. I replaced VR3 on my 2020B. Along with EVERY FUCKING TRANSISTOR AND ELECTROLYTIC CAPACITOR ON THE FUCKING FUCKER. PLUS U1 and U2.

Same exact shit as before. (I guess I had fried VR3 when I shorted the body of Q1 to ground.)

Not only that, but despite being pin for pin compatible and the specs being the same, the u741 won't replace the CP02-whatever OpAmp. So I've got to locate some NOS on eBay to see if that's my issue.

I'm at a loss for what to do if that doesn't work. It has to be in the feedback loop there somewhere.


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Careful on replacing opamps that use the nulling pins. There are 2 ways to use them, and the difference is in which power rail it references to. Use the wrong one and it will instantly blow up the input stage of the opamp.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 01, 2014, 11:43:13 pm
Damn, yeah you guys are right. For some reason I always thought the 741 was a direct replacement, but turns out it's only pin compatible. *Sighs*

I've got a LT1097 on the way (not very expensive) that should do the job.


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Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 01, 2014, 11:48:53 pm
What do you guys think about designing a replacement for the internals of these supplies? I am thinking of:

- Replacement PCB using ... Op-amps instead of transistors except for the output drive stage.

This is not difficult to do but only the input stages of the error amplifiers matter.  An alternative to replacing them is to use operational amplifiers to correct their offset and low frequency noise and drift.

That would be a lot better time spent than me re-designing the 2005A amplifier oven. Don't you think?

Edit: Though I might still do the 2005A Amplifier.

The 2005A design shows that Power Designs used a dual transistor as the error amplifier and stuck it into the oven to do these very things.  Improve the error amplifier and change the reference and the oven can be left out.

Sorry, I should have been more specific. I didn't mean use the 2005A error amp as part of a new control board. In moto's thread I was talking about designing a replacement for the 2005A's entire oven unit using modern SMD components, complete with a PCB based heater, to stick in a small 3D printed case.

The idea being it will fit in the hole left by the removal of the current oven on 2005A units.

An alternative to dealing with broken heaters and thermostats, etc. 


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 02, 2014, 03:22:37 pm
Sorry, I should have been more specific. I didn't mean use the 2005A error amp as part of a new control board. In moto's thread I was talking about designing a replacement for the 2005A's entire oven unit using modern SMD components, complete with a PCB based heater, to stick in a small 3D printed case.

The idea being it will fit in the hole left by the removal of the current oven on 2005A units.

An alternative to dealing with broken heaters and thermostats, etc.

I think you could get away with a modern precision operational amplifier replacing the differential pair without temperature stabilizing that part.  Power Designs needed the oven not only for their reference but also because the differential pair they used while better than discrete transistors is poor compared to an integrated transistor pair.

Looking at the schematic however, I think the easiest replacement using an operational amplifier to replace Q3 would include bypassing Q8 and Q9 because they add a lot of unnecessary gain making frequency compensation difficult but it should still be possible to leave them in with careful design.

Another alternative I would consider is using almost the same oven board schematic without the oven but replacing Q3 with a modern integrated transistor pair like an Analog Devices MAT01 or SSM2212 or Linear Systems monolithic dual transistor and using the LM399A or reference of your choice.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 03, 2014, 03:40:33 am

Sorry, I should have been more specific. I didn't mean use the 2005A error amp as part of a new control board. In moto's thread I was talking about designing a replacement for the 2005A's entire oven unit using modern SMD components, complete with a PCB based heater, to stick in a small 3D printed case.

The idea being it will fit in the hole left by the removal of the current oven on 2005A units.

An alternative to dealing with broken heaters and thermostats, etc.

Another alternative I would consider is using almost the same oven board schematic without the oven but replacing Q3 with a modern integrated transistor pair like an Analog Devices MAT01 or SSM2212 or Linear Systems monolithic dual transistor and using the LM399A or reference of your choice.

Yeah, I had already settled on Q3 being a MAT01.

So, you don't think there's any benefit to using PCB traces to keep the entire thing at a constant 50c to minimize drift?

Though I imagine with an LM399 and MAT01, you're going to have drift in other places like the selection resistors etc. so it might not matter.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 03, 2014, 06:16:26 am
Another alternative I would consider is using almost the same oven board schematic without the oven but replacing Q3 with a modern integrated transistor pair like an Analog Devices MAT01 or SSM2212 or Linear Systems monolithic dual transistor and using the LM399A or reference of your choice.

Yeah, I had already settled on Q3 being a MAT01.

So, you don't think there's any benefit to using PCB traces to keep the entire thing at a constant 50c to minimize drift?

I doubt there will be any benefit in using an oven if modern low drift parts are used.

Quote
Though I imagine with an LM399 and MAT01, you're going to have drift in other places like the selection resistors etc. so it might not matter.

Exactly.  Calculate the worst case error contributed by the LM399 and MAT-01 and see if it stays within the original specifications.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 03, 2014, 11:34:49 am
The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 03, 2014, 01:20:42 pm
The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)

It has a pass transistor and heater control circuit which operate linearly.  The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C.  At 25C, it draws about 300 milliwatts.  Operating voltage is from 9 to 40 volts.

The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 03, 2014, 01:26:03 pm

The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)

It has a pass transistor and heater control circuit which operate linearly.  The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C.  At 25C, it draws about 300 milliwatts.  Operating voltage is from 9 to 40 volts.

The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.

Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)

It would help keep things original looking too.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 03, 2014, 02:21:57 pm
I’m the fool who bought the latest 5020 that was sold on E-Bay, if only just to have some fun with it and add it to my PD collection so to say, which are all power supplies in regular use.  Not too badly priced at $129.00.  I could have waited for one to come along cheaper, but this is the exact PD precision model I have wanted.  Claimed to be, “guaranteed working.”  Yeah, I know darn well how that often goes!  Cosmetically the front doesn’t look like anything that won’t clean up fairly decent, and I’ll strip the old paint and give the outer cabinet a fresh spray of Krylon Bahama Sea blue.  This was one of the last precision models made by the “real” Power Designs company looking to have been designed around 1978 or so, and it uses the LM399 reference. 

-Mark-
 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 03, 2014, 11:36:03 pm
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 03, 2014, 11:42:44 pm

The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)

It has a pass transistor and heater control circuit which operate linearly.  The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C.  At 25C, it draws about 300 milliwatts.  Operating voltage is from 9 to 40 volts.

The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.

Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)

It would help keep things original looking too.


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Or you could use the LTZ1000, which has an internal heater but external heater control. But actually, I think that LM399 heats up so quickly that it doesn't make sense to even have an oven light. These parts don't have to heat up a giant mass since it's just a heater built into the substrate of the chip.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 04, 2014, 02:04:07 pm

The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)

It has a pass transistor and heater control circuit which operate linearly.  The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C.  At 25C, it draws about 300 milliwatts.  Operating voltage is from 9 to 40 volts.

The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.

Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)

It would help keep things original looking too.


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Or you could use the LTZ1000, which has an internal heater but external heater control. But actually, I think that LM399 heats up so quickly that it doesn't make sense to even have an oven light. These parts don't have to heat up a giant mass since it's just a heater built into the substrate of the chip.

Yeah, I was thinking about that. I measured one of my LM399H's current draw last night and it's pretty variable, so in the end I may just PWM an LED to reflect that for the oven light. This is all putting the cart before the horse anyway, just something fun I thought of.

Anyway, I built up the existing oven board into my basic simulator last night (iCircuit), just to get a feel for it and make sure I understand how everything works. I'll provide the file if anyone is interested. (I'm working on the entire 2005A as well; just breaking it down into sub-circuits). This isn't anywhere near as complex as LT Spice, but seeing the current actively flow is an invaluable reverse engineering aid I've found!

(http://img.timb.us/2005_Ref.png)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 04, 2014, 03:55:21 pm
that is great. Please share the 2005a circuit when you are done.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 04, 2014, 04:25:30 pm
You can compare the schematics of the supplies using the older style reference to those using the LM399 and see that in the late 70's PD took the time to more or less re-engineer the whole thing when they changed the voltage reference to the to LM.  That may or may not be the path you end up taking if attempting to convert to a more modern voltage reference and end up with a supply that works the way it should. 

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 04, 2014, 08:46:52 pm
Yeah, I've got a 2020B as well that uses the 399. I suspect part of the redesign was to use more modern components and techniques as well, as some of the parts in the 2005A series were EOL by the mid-70's! Luckily the LM399's nominal voltage falls in line with that of CR9 on the 2005A ref, so it might be doable.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 05, 2014, 12:04:13 pm
I picked up some paint to redo my cases today. It's Rustoleum "Lagoon".

Here's a test spot with normal house lighting:

(http://tapatalk.imageshack.com/v2/14/11/05/ab3f0f1adff949dbe0317b62fc981774.jpg)

Now under white LED lighting:

(http://tapatalk.imageshack.com/v2/14/11/05/a04ef38dffcc8497a620b2dc13aff334.jpg)

It doesn't look anywhere near that blue in person. The other option was Krylon's "Jade" but I thought it would be too green.

Personally, I kind of dig the color; sets it apart from Tektronix gear, so I might go with it, even for the units I resell.

In other news, that new OpAmp will be here today, so I need to get the front back on the 2020B!

(http://tapatalk.imageshack.com/v2/14/11/05/20e96a5c341af1f5f72c5adedb71b9e5.jpg)

I took it off to really clean and test the switches and pots. I tested the switch bank, with a four wire lead hooked up, I went through the entire range from least significant decade up. With the switches set to 9.99[10] I got 10.00001k on my 6.5 digit HP '57A. Not a signal damn resistor was out. After 35 years!

I also took the current pot/switch and vernier apart, scrubbed them out good, relubed with WD-40's White Lithium Grease (that stuff is amazing; you spray it and it "drys" into a normal film of lithium grease), then used DeOXIT Shield to protect the wiper contacts.

The switch portion of the current pot got sprayed with WD-40 Silicone Lubricant and the contacts cleaned and shielded with DeOXIT.

(http://tapatalk.imageshack.com/v2/14/11/05/896501c7e066ae873d8981eaac08de8f.jpg)

What do you guys think for the moving parts of the switch banks, lithium grease or silicone lubricant?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 05, 2014, 01:44:49 pm
Paint looks good.

I was told to use lightweight grease for the bearings/moving parts. I ended up using some firearms lubricant that I had. It is sort of like a slightly runny grease.

BTW - how did you ship that nichrome wire? I am sort of surprised it isn't here yet.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 05, 2014, 03:11:43 pm
The paint looks nice, sometimes a little change is good.  Krylon Bahama Sea is about the closest you can find to "Tektronix" blue at the store, but not everyone who sells Krylon carries the color. 

With precision instrumentation contacts I clean them with anything I know won't leave any residue film, CRC QD cleaner is pretty good as is pure isopropyl alcohol.  Sometimes heavily built up oxides make this hard to do though, and you have to break out something from Caig with a bit of acid in it- just rinse it off really good with IPA after cleaning so that the contacts are dry and film free. 

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 05, 2014, 05:40:43 pm
Yeah, I clean with 97% Isopropyl. Sometimes I use a bit of Dawn dish soap and a toothbrush first to get rid of grease and oils, then scrub with the Iso, then a final rinse with either 25/75 Iso/Distilled Water or the straight Iso, which speeds drying and doesn't leave water spots!

I use the original DeOXIT for oxidized contacts. Good stuff.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 05, 2014, 05:43:16 pm

Paint looks good.

I was told to use lightweight grease for the bearings/moving parts. I ended up using some firearms lubricant that I had. It is sort of like a slightly runny grease.

BTW - how did you ship that nichrome wire? I am sort of surprised it isn't here yet.

First class, let me know if it's not there today. I'll send another batch Priority I guess.

I should have known better as I've been having massive delays with first class stuff lately. :(


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 05, 2014, 06:07:47 pm
It has a pass transistor and heater control circuit which operate linearly.  The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C.  At 25C, it draws about 300 milliwatts.  Operating voltage is from 9 to 40 volts.

Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)

Your PWM idea is good.  What I was thinking is that since the warmup time is pretty short, an operational amplifier differentiator could be used to detect the period of time when the reference temperature has not stabilized making the oven indicator a warming up indicator.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Alex Eisenhut on November 05, 2014, 08:06:29 pm
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!


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EE dep't at a university?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 06, 2014, 09:38:43 am
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.

The new OpAmp for my 2020B came in today, yay! Still finishing up the front panel though so haven't tried it yet. I got the vernier and current pots feeling like brand new now.

I've also the power and sense wires that normally go to the banana connector soldered together with a short 2ish inch extension wire, since they were snipped too short when removing the OEM jacks. The plan is to use rung style crimp connectors for power, the original capacitor board for the caps, plus a small wire from where a cap hooks to - and + which will go to the meter switch.

This should be a lot nicer than soldering everything on outright.

(http://tapatalk.imageshack.com/v2/14/11/06/2459d068546afb2473165d3eda7f9e2b.jpg)

That front panel is in pretty bad shape. No matter how much scrubbing and cleaning I do. Eventually I'd like to have a custom one produced, with room for a long dual led bargraph and some HP bubble displays in lieu of a mechanical meter.

(http://tapatalk.imageshack.com/v2/14/11/06/aeb4c41fcd42b72ebfbdcf9b92a28070.jpg)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 06, 2014, 11:18:43 am
sounds like it is all starting to come together.

BTW - no joy on that wire. Can you PM me the address you used so I can make sure there wasn't a typo or something?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 06, 2014, 02:17:26 pm
It's looking good!  Sometimes Maguar's cleaner wax or even a little toothpaste can help to hide those old sticker shadows on aluminum panels.

The college I work at (Penn State) doesn’t keep much of anything old around as far as literature or equipment, because they don’t teach anything old school in the electrical engineering classes.  You learn the basics in physics classes, and the engineering classes are either what is around now, or what is to be.  A power supply like the Power Designs precision models would garnish little more than snickers, that from most college kids who have no understanding of what it is.  To them, it would be something tossed to the curb because it’s not what they are being taught to use for the development of the next generation of iPad. 

I got my 5020 toy yesterday.  Not too bad, about par for the course, it did power up and work to a fairly good degree on initial test.  I checked all the e-caps and most tested excellent short of the 4 Sprague 1uF 100 volt ones that had ridiculously high ESR and leakage thus will be replaced.   The switch contacts are sketchy as expected also and need a good cleaning.   But even with that, the output voltage would stabilize nicely after about 15 minutes down to the last digit on my 3456A.  So hopefully this one will end up calibrating well after repair and not turn in to one of those continuous science projects. 

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Alex Eisenhut on November 06, 2014, 03:53:19 pm
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.


I can look at Concordia here, they had 1960s stuff back when I looked for vintage Tek parts info.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 06, 2014, 03:56:15 pm
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.


I can look at Concordia here, they had 1960s stuff back when I looked for vintage Tek parts info.

Ha!  A fellow Montrealer! :D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 06, 2014, 04:27:42 pm
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!

In the case of the interesting parts, I suspect Power Designs was grading them anyway so the original specifications would be of limited use.  I usually end up reverse engineering the circuit in detail to find out what the specifications needed to be.

If I wanted to work from the part number, I would start is one of the Derivation and Tabulation Associates "D.A.T.A" books.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 06, 2014, 05:19:01 pm
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!

In the case of the interesting parts, I suspect Power Designs was grading them anyway so the original specifications would be of limited use.  I usually end up reverse engineering the circuit in detail to find out what the specifications needed to be.

If I wanted to work from the part number, I would start is one of the Derivation and Tabulation Associates "D.A.T.A" books.

They were definitely grading them. I forget where exactly it says this, but somewhere in the 2005A manual it mentions that the parts were selected from batches for specific qualities (probably transistor Beta).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 06, 2014, 05:43:15 pm
A fellow on the Antique Radio forum said they did their own semiconductor matching in house.  I have seen some Sprague electrolytics in these supplies labeled, "For Power Designs," but I'm not sure what would be so special about them.  I know at least in the HV supplies, they made their own transformers rather than buy them from suppliers. 

-Mark-


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 06, 2014, 07:25:31 pm
A fellow on the Antique Radio forum said they did their own semiconductor matching in house.  I have seen some Sprague electrolytics in these supplies labeled, "For Power Designs," but I'm not sure what would be so special about them.  I know at least in the HV supplies, they made their own transformers rather than buy them from suppliers.

I wondered about that when looking through their parts lists because almost all of the parts including capacitors have Power Designs listed as the manufacturer.  A similar parts list from Tektronix would list the source of the parts separate from any graded specifications.

I assume besides grading that Power Designs did extensive quality assurance on all of their incoming parts.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Alex Eisenhut on November 06, 2014, 07:36:06 pm
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.


I can look at Concordia here, they had 1960s stuff back when I looked for vintage Tek parts info.

Ha!  A fellow Montrealer! :D

Yup, there's also McGill, ETS, and maybe UQAM that might have musty old books.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on November 06, 2014, 09:39:59 pm
Do you have a model number of the diode, I have a reference book from 1965.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 06, 2014, 10:33:53 pm
2005A Circa 1977

Silicon Zener:
TS823H2
TS823G
TS823

Silicon Diode:
GI44

2005 Circa 1966

Silicon Zener:
AC359C
AC359D
AC359BT

Edit: You may have better luck adding 1N instead of the first two letters to some of these. It seems either PD added a two letter manufacturers code to part numbers or that's how it was back in the day? No idea who TS or AC is, but 1N823 turns up hits on Google. Perhaps the suffix was a grade or binning code added by PD?

Maybe I should sacrifice this 2005A reference and desolder the parts so I can analyze them in detail. 

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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 06, 2014, 10:46:43 pm
One other thing I've noticed about PD, is they used mainly plastic film and tantalum/tantalytics in these precision supplies. Very few AE or ceramic caps.

I replaced all the AE's in my 2020B, even though they were still spot on after 34 years, just in case. (There were two small 1uF ones, then three larger ones.)

Should I be worried about the wet tantalum caps leaking? They're in fully sealed little metal axial can packages and the values are still perfect.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 07, 2014, 02:08:35 am
Should I be worried about the wet tantalum caps leaking? They're in fully sealed little metal axial can packages and the values are still perfect.

They may eventually leak sulfuric acid but inspection of the ends will reveal any corrosion if this starts to happen.

I do not have a good idea of what an appropriate replacement is for wet tantalum capacitors.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on November 07, 2014, 04:32:37 am
If the tantalum caps have a glass end don't bother, they will outlive you. If the end is rubber they will need to be replaced. Having the caps made for them was probably to get a low ESR ( for the time) or a higher ripple current capacitor, so internally they might have thicker foil and multiple tabs for each electrode. As well they would likely have had a spec for both tolerance and voltage rating with surge rating.

TS is TRW Semiconductors and AD is AC Delco. Both no longer exist. The parts were most likely house coded parts specially made for PD, either a selected grade of regular production, a house coded part to control spares availability ( lock in for OEM spares) or a specially made part. My bets are they were regular parts with the house code so as to get the units returned to PD for service.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 07, 2014, 06:40:50 am
If the tantalum caps have a glass end don't bother, they will outlive you. If the end is rubber they will need to be replaced.

I have seen photos of hermetically sealed ones which failed as I described but it is apparently so rare that it is not something I would worry about.

Quote
Having the caps made for them was probably to get a low ESR ( for the time) or a higher ripple current capacitor, so internally they might have thicker foil and multiple tabs for each electrode.

Their claim to fame now seems to be long life, high reliability, and high temperature operation.  Once I have one fail, I will do a serious search to find suitable replacements.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 07, 2014, 10:13:55 am
Interesting info, thanks. I'll check the ends and see how they're sealed.

Here's six in a small area of the 2020B board:

(http://tapatalk.imageshack.com/v2/14/11/07/618ba461810c93176595e11cc56e54d7.jpg)

(They're the silver (metal) axial lead cans.)

I had a grey beard who restores old radios once tell me tantalytics were the best type of cap you could buy (in the 1960's at least). He said that he has to replace about 1 in 1000 he sees (this was at least 14 years ago though so things have perhaps changed).


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 07, 2014, 12:12:25 pm
There were several tantalytics in a Dymec 2401A I just finished refurbishing, made in 1962.  Not a single one of those was bad, this in a machine with a LOT of operating hours on it, so it's safe to say they are durable have a very long lifespan if in circuits where they aren't stressed too much.  If in doubt you can lift a lead and do the standard capacitance/ESR/current leakage tests, but if they are within tolerance IMHO it's probably best to leave them be in the not-broken-don't-fix-it tradition. 

Like I mentioned earlier I only found 4 bad electrolytics in the 5020.  All others tested to be in excellent condition. 

-Mark-
 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 07, 2014, 01:57:30 pm
Yeah, I randomly spot checked about 5 of the highest stressed ones I could and they all had beautiful ESR and spot on capacitance values, so I concur. Same with the low value orange plastic film caps (also seen in the photo above). I was curious about their use as well, as most modern (and even older equipment) would simply use ceramics.

In fact, the only ceramic on this thing is C10, which is a 1kvdc 100pf going from the output of the voltage regulation OpAmp to the inverting input. (So I guess they're just AC coupling the feedback?)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 07, 2014, 02:37:25 pm
As you can see from this thread I have purchased quite a few PD supplies and I was fortunate that none of them had any serious problems other than needing a thorough switch cleaning. I have also sold many of them since jumping ship to the HP 611X supplies. All that I sold were burnt in for at least 24 hours at max load before calibration without any problems.

IMO on these PD supplies if it aint broke don't fix it ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 07, 2014, 06:34:24 pm
I just got myself a Power Designs 2020B (with a pretty high serial number, woohoo) after reading this thread in its entirety, so please welcome me to the PD club. After properly calibrating the 0 V value and the highest voltage value per the calibration instructions using a 6 1/2 digit voltmeter as a reference, I have found some non-linearity in the voltage selection.

When switching between 5.000 V and 6.000 V (maybe it was between 4 V and 5 V), I noticed that the voltage coming out of the power supply goes from almost dead-on correct to about 1.4 mV higher than it should be. I realize that this is a small error, but it continues for all of the other unit voltage numbers above the threshold number (say 5 V, so e.g., 6 V, 7 V, 8V and so on). It is as if there is a resistor in place for the range 5-9 (whole) volts that kicks in after you cross the threshold and it is slightly off.

If someone can point me to the exact resistor this is among the many resistors connected to the rotary switch, I would really appreciate it, because it's really hard to tell what's what.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 07, 2014, 08:04:01 pm
I just got myself a Power Designs 2020B (with a pretty high serial number, woohoo) after reading this thread in its entirety, so please welcome me to the PD club. After properly calibrating the 0 V value and the highest voltage value per the calibration instructions using a 6 1/2 digit voltmeter as a reference, I have found some non-linearity in the voltage selection.

When switching between 5.000 V and 6.000 V (maybe it was between 4 V and 5 V), I noticed that the voltage coming out of the power supply goes from almost dead-on correct to about 1.4 mV higher than it should be. I realize that this is a small error, but it continues for all of the other unit voltage numbers above the threshold number (say 5 V, so e.g., 6 V, 7 V, 8V and so on). It is as if there is a resistor in place for the range 5-9 (whole) volts that kicks in after you cross the threshold and it is slightly off.

If someone can point me to the exact resistor this is among the many resistors connected to the rotary switch, I would really appreciate it, because it's really hard to tell what's what.

Have you cleaned the switch contacts? This almost always needs to be done, and leads to voltages being off as you move between different values. There's instructions earlier in this thread, but in general the process is:

Spray out any dust and dirt with compressed air
Clean everything with a mild, general purpose electronic cleaner
Clean the contacts with some DeOxit Red
Use the electronics cleaner to remove any deoxit red
Apply some deoxit gold to the contacts and leave this in place
Re-lube the switch bearings and points where the metal rubs with some lightweight grease (just don't get this on the contacts).

Then recalibrate, and I bet your unit will work fine.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 07, 2014, 09:00:18 pm
I just got myself a Power Designs 2020B (with a pretty high serial number, woohoo) after reading this thread in its entirety, so please welcome me to the PD club. After properly calibrating the 0 V value and the highest voltage value per the calibration instructions using a 6 1/2 digit voltmeter as a reference, I have found some non-linearity in the voltage selection.

When switching between 5.000 V and 6.000 V (maybe it was between 4 V and 5 V), I noticed that the voltage coming out of the power supply goes from almost dead-on correct to about 1.4 mV higher than it should be. I realize that this is a small error, but it continues for all of the other unit voltage numbers above the threshold number (say 5 V, so e.g., 6 V, 7 V, 8V and so on). It is as if there is a resistor in place for the range 5-9 (whole) volts that kicks in after you cross the threshold and it is slightly off.

If someone can point me to the exact resistor this is among the many resistors connected to the rotary switch, I would really appreciate it, because it's really hard to tell what's what.

Have you cleaned the switch contacts? This almost always needs to be done, and leads to voltages being off as you move between different values. There's instructions earlier in this thread, but in general the process is:

Spray out any dust and dirt with compressed air
Clean everything with a mild, general purpose electronic cleaner
Clean the contacts with some DeOxit Red
Use the electronics cleaner to remove any deoxit red
Apply some deoxit gold to the contacts and leave this in place
Re-lube the switch bearings and points where the metal rubs with some lightweight grease (just don't get this on the contacts).

Then recalibrate, and I bet your unit will work fine.

Why use deoxit gold if there are no gold contacts in there?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 07, 2014, 09:09:19 pm
It is an excellent contact lube in general. The only exception is cermet or carbon pots where Caig Fader lube is a better choice
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 07, 2014, 10:59:36 pm
Yes, +1 to what robrenz said. The DeOxit Gold is a preservative / protectant and lube for the contacts.

Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 07, 2014, 11:53:54 pm
I personally prefer the DeOXIT Shield myself on anything fully open to the free air, like the switch banks on these units are.

While putting my 2020B back together I did some experiments with lubricants and found WD-40's spray-on White Lithium Grease and Silicone Lubricants to both be excellent choices, but I feel like the Silicone Spray edges the other out in the least mess and protection factor areas, so that's what I'm going with. Though, if you want a good long lasting lube that's easy to apply and find, you can't go wrong with Hopp's #9 Gun Lube (orange bottle), available at Wal-Mart or anywhere firearms are sold.

I use DeOXIT Gold inside the  wirewound pots, plus Silicone Lubricant for the shaft and Lithium Grease for the bearings.

By the way, for really bad problems with pots or switch banks, don't be afraid to desolder the connections, remove them, use the original spray on DeOXIT and then scrub them in a sink full of warm water and dishwashing soap with a toothbrush. Followed by a hot water rinse to get the soap out, then a rinse with 90+% IPA. Followed by the prescribed lube and protect procedure above.

You can remove pots and take the cover off them (a couple of metal bend tabs) and do the same thing.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 08, 2014, 12:25:29 am
OK, I may have found what is causing the 1.4 mV drift going from 5 V to 6 V. There is a 1 k 0.05% resistor in there that I measured at 930 ohms. I don't know if this is the circuit contribution or if it has fallen out of spec over time.

If it has fallen out of spec, I am wondering if that is enough out of tolerance on such a precise part to cause the problem. It seems that this (black) resistor goes in-circuit on the switch from 5 V to 6 V. Because it measures less, I am wondering if it skews the divider circuit enough to cause the 1.4 mV drift for voltages where the 1's digit is greater or equal to 6.

I'll see if I can get a picture of the particular resistor I am talking about over the weekend and perhaps some of you with the 2020B can help out by measuring the resistance on your unit of that resistor in circuit and let me know if it's supposed to measure low (e.g., due to the contribution of other circuit elements).

I am very hesitant to clip or desolder it in order to measure it in isolation, unless I find no other way. It's easy to decrease resistance in circuit with a parallel resistor, but increasing it is kind of tough without doing some "damage," so that's my path of last resort.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 08, 2014, 01:06:48 am
Set all switches to 0 and put it on the 0-10V range, after that you you should be able to measure the resistors individually.

How are you doing the measurements? With a 4-wire kelvin clip I assume?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on November 08, 2014, 02:36:44 am
That 1k resistor at .05% should have a tolerance of +/- 0.50 ohms. So it is out of spec.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 08, 2014, 04:57:40 am
Yeah, all the switch resistors in my 2020B are dead on. Even the 5% and 1% tolerance ones are +/- 0.001Ohms. With all the switches in their full positions, I get exactly 10,000.01Ohms on my 6.5 Digit HP'57. So yours seems out for sure.

I might have a replacement here if you want it.


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Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 08, 2014, 11:59:01 am
Boom goes the dynamite! My 2020B is alive, again!

(http://tapatalk.imageshack.com/v2/14/11/08/016d92ead743199b20d8ffd9b6a7ed9c.jpg)

Set for 10V and my 3456A is showing 10.00008V there in the background.

So, what was it? It appears to be the OP05 was the culprit (one of my initial guesses).

(http://tapatalk.imageshack.com/v2/14/11/08/50ba2a0376705c71e9e92f30a8588093.jpg)

Popped in the new LT1097 and she seems to work fine with one issue: I'm about -26mV at a switch setting of zero, with no more turns on the zero pot left. I guess I could always add some inline resistance to the offset input, right? Or a larger pot.

Either way I'll read up on the LT1097 today and figure out how to modify the 2020B accordingly.

I also pretty much got everything done on the front panel. All I have left is to hook up the 10-20V switch, plus the indicator lamps and finally, cover the hole where the meter goes temporarily.

This time I used all crimp connections for the banana jacks; well worth it IMHO if I ever need to remove the panel again!

(http://tapatalk.imageshack.com/v2/14/11/08/3a2784d9624f31b81a36a3577c37f50d.jpg)

(http://tapatalk.imageshack.com/v2/14/11/08/110a3b8463b7f9ff63093cf80538a1e8.jpg)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 08, 2014, 01:55:52 pm
Nicely done.  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 08, 2014, 04:39:07 pm
Yeah, all the switch resistors in my 2020B are dead on. Even the 5% and 1% tolerance ones are +/- 0.001Ohms. With all the switches in their full positions, I get exactly 10,000.01Ohms on my 6.5 Digit HP'57. So yours seems out for sure.

I might have a replacement here if you want it.


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Say where are you measuring from/to to get that 10,000.01. I have a 3456A as well, so I can perform the measurement and see what I come out to...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 08, 2014, 05:55:07 pm
Popped in the new LT1097 and she seems to work fine with one issue: I'm about -26mV at a switch setting of zero, with no more turns on the zero pot left. I guess I could always add some inline resistance to the offset input, right? Or a larger pot.

Either way I'll read up on the LT1097 today and figure out how to modify the 2020B accordingly.

The LT1097 has a much smaller offset null range (+/- 600uV) than the OP-05 (+/- 4mV).  If they were relying on this to correct for other errors which is generally a bad practice, then something else may have to be done.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 08, 2014, 06:13:19 pm
Here are the measurements I've got. If someone can compare them to their unit I would appreciate it:

(Click on any image to view it full screen)

2020b 4-wire Kelvin resistance measurement connection location:

(http://s28.postimg.org/625pxuy5p/4_wire_connection.jpg) (http://s28.postimg.org/625pxuy5p/4_wire_connection.jpg)

2020b settings (all maxed out, including vernier):

(http://s11.postimg.org/iw79g11ub/2020b_settings.jpg) (http://s11.postimg.org/iw79g11ub/2020b_settings.jpg)

4-wire measurement results on HP 3456A:

(http://s2.postimg.org/8gqm4yae1/4_wire_reading.jpg) (http://s2.postimg.org/8gqm4yae1/4_wire_reading.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 08, 2014, 06:47:16 pm

Yeah, all the switch resistors in my 2020B are dead on. Even the 5% and 1% tolerance ones are +/- 0.001Ohms. With all the switches in their full positions, I get exactly 10,000.01Ohms on my 6.5 Digit HP'57. So yours seems out for sure.

I might have a replacement here if you want it.


Sent from my Smartphone

Say where are you measuring from/to to get that 10,000.01. I have a 3456A as well, so I can perform the measurement and see what I come out to...

With the supply off, the range set to 0-10V and the vernier fully counterclockwise, look at the board on the back of the switch array and you should see three lugs with a 10K resistor across the top two. Test from the center lug and DC- terminal.

Basically, one end of the vernier is connected to DC- and the other end to the bottom lug, which connects to the switch banks, from there it goes from S5 to S6 then the top lug of the switch board (input of that 10k resistor), the center lug (output of that 10k resistor) connects to RV2 on the back, which straps to RV1 and goes to the main board voltage OpAmp! By the way, that 10k resistor is bypassed when the front switch is in the 10V position.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 08, 2014, 07:05:32 pm

Yeah, all the switch resistors in my 2020B are dead on. Even the 5% and 1% tolerance ones are +/- 0.001Ohms. With all the switches in their full positions, I get exactly 10,000.01Ohms on my 6.5 Digit HP'57. So yours seems out for sure.

I might have a replacement here if you want it.


Sent from my Smartphone

Say where are you measuring from/to to get that 10,000.01. I have a 3456A as well, so I can perform the measurement and see what I come out to...

With the supply off, the range set to 0-10V and the vernier fully counterclockwise, look at the board on the back of the switch array and you should see three lugs with a 10K resistor across the top two. Test from the center lug and DC- terminal.

Basically, one end of the vernier is connected to DC- and the other end to the bottom lug, which connects to the switch banks, from there it goes from S5 to S6 then the top lug of the switch board (input of that 10k resistor), the center lug (output of that 10k resistor) connects to RV2 on the back, which straps to RV1 and goes to the main board voltage OpAmp! By the way, that 10k resistor is bypassed when the front switch is in the 10V position.


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I measure a 5.10539 kOhm 4-wire Kelvin resistance measurement from the center lug to DC- with:

- The power supply turned off
- The voltage range set to 0-10 V
- The vernier turned fully counterclockwise
- All voltage select dials turned to their maximum positions (i.e., (http://s27.postimg.org/tzys8fgn3/9_9910.png))
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 08, 2014, 07:19:06 pm
Hmmm, that's weird. You may have to unsolder that white and orange-brownish wire from the bottom and top lugs on the back switch board. That's the way I measured my switches, directly from those two wires after unsoldering them.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 09, 2014, 12:34:10 am
Sadly, I decided to present the 2020B with a 0.5 A load and the voltage dropped significantly. The current limit knob is set to its maximum position (i.e., turned all the way clockwise), so I am not being current limited. Also, the voltage range lamp doesn't flash to indicate that current limiting in effect. It is just misregulating.

At a 5 V, almost perfect setting with no load, I am only getting 4.319 V into the 10 ohm resistive load. I removed the bottom panel and noticed that there are three additional trim pots on the main board. Trim pot R8 controls the maximum current output. I have adjusted it for a 2.1 A output using a setting of 5 V, as instructed in the manual. Trimmer pot R104 is a mystery - I have no idea what it does and its function is not stated on the circuit diagram in the Operating Guide.

At larger voltages, such as 15 V, I am getting a drop of something like a volt and a half into a 1.5 A load (this time), again without any sort of current limiting kicking in.

Also, I noticed that the label above the current knob says, "Pull to set." However, the current limit can be adjusted without pulling the knob (tested with both an ammeter connected directly to the DC-/DC+ terminals and with a load present combined with an ammeter in series). What is even weirder is that if I do pull out the Current adjustment knob all that happens is that the current is limited to half of the available current range (i.e., instead of a 0-2 A adjustment, it becomes approx. a 0-1 A adjustment) further reducing the current output capability of the device while the knob remains pulled out. It doesn't make any sense to me. How the heck is this knob supposed to function when it's pulled out vs. pushed in?

Here is a high quality high resolution picture of the front of the 2020B's main circuit board (To see it in full resolution, click on the image and then click again on the resulting image in your browser to zoom in to 100%):

(http://s27.postimg.org/6vl9x654x/2020b_circuit_board.jpg) (http://s27.postimg.org/6vl9x654x/2020b_circuit_board.jpg)

I would like to get the supply's load voltage to match its no load voltage, so any help would be appreciated. Maybe U1b (current limiting amplifier) is bad, but if that was the case, why is the voltage into no load almost spot on? The shape and color of R38 is suspicious, I will measure it to see if it's good.

Update: I thought that R38 (the resistor that looks like a burned marshmallow under the topmost blue trimmer pot) looked a bit weird, but it checks out fine at its rated 0.15 Ohms.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on November 09, 2014, 03:37:36 am
That resistor doesn't look good. I would check it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 06:06:32 am
It could be one of the series pass transistors is bad. You can replace any of the TO3 transistors with an easy to obtain 2N3773 and it’ll work fine. Also check Q3, which is responsible for pushing the power transistors.

U1 *could* be bad, but it’s easy to obtain a replacement on DigiKey or Mouser. (You can use the normal plastic DIP package version instead of the $8 metal can package. Though I’ve got a spare metal can version if you want it.)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 06:09:30 am
Popped in the new LT1097 and she seems to work fine with one issue: I'm about -26mV at a switch setting of zero, with no more turns on the zero pot left. I guess I could always add some inline resistance to the offset input, right? Or a larger pot.

Either way I'll read up on the LT1097 today and figure out how to modify the 2020B accordingly.

The LT1097 has a much smaller offset null range (+/- 600uV) than the OP-05 (+/- 4mV).  If they were relying on this to correct for other errors which is generally a bad practice, then something else may have to be done.

I took a 100k resistor and hooked it between ground and pin 8 (one of the offset inputs) of the LT1097 and now I’m able to get it zeroed out. Though I’m not sure how this will affect things longterm? Will it hurt the OpAmp? Should I balance things out by sticking the same value resistor on the the other offset input as well?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 09, 2014, 07:11:30 am
Popped in the new LT1097 and she seems to work fine with one issue: I'm about -26mV at a switch setting of zero, with no more turns on the zero pot left. I guess I could always add some inline resistance to the offset input, right? Or a larger pot.

Either way I'll read up on the LT1097 today and figure out how to modify the 2020B accordingly.

The LT1097 has a much smaller offset null range (+/- 600uV) than the OP-05 (+/- 4mV).  If they were relying on this to correct for other errors which is generally a bad practice, then something else may have to be done.

I took a 100k resistor and hooked it between ground and pin 8 (one of the offset inputs) of the LT1097 and now I’m able to get it zeroed out. Though I’m not sure how this will affect things longterm? Will it hurt the OpAmp? Should I balance things out by sticking the same value resistor on the the other offset input as well?

I do not think you will damage it.  You can check the LT1097 schematic which shows how the nulling works.  The change in collector voltage on one side is small.

The reason it is a bad practice is that with these types of operational amplifiers, their input offset voltage drift is minimized when their input offset voltage is minimized so if you null them to a specific offset to correct for other errors, their input offset voltage drift is compromised.  Since Power Designs apparently did exactly this, I assume the increase in drift is not significant.

It still seems a little odd to me so I would try looking for other problems which would cause a large offset but that could be difficult.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 07:17:41 am
Okay, this is really fucked up. I accidentally fried the LT1097 (I grounded one of the offset inputs without a resistor attached by dropping a lead; no smoke, just stopped working), so on a whim I stuck the original OP-05 back in and… It’s fucking working. Seriously. Spot on, too.

I’ve honestly got no clue. The only thing that has changed is I don’t have the 10/20V selection switch wired in right now. I wonder if that’s somehow bad? Hmmm.

Or maybe something was messed up with the offset circuit? I un-soldered the adjustment pot, so maybe it was somehow shorting and all this fiddling has fixed it? Without the zero adjust pot even connected, I’m only getting -300uV of offset, which that LT1097 should have easily been able to null out. So, something weird is going on. (Hooking the pot back up with the OP-05 and I’m able get it down to around 5uV of offset.)

This one is truly baffling.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 09, 2014, 02:36:13 pm
Okay, this is really fucked up. I accidentally fried the LT1097 (I grounded one of the offset inputs without a resistor attached by dropping a lead; no smoke, just stopped working), so on a whim I stuck the original OP-05 back in and… It’s fucking working. Seriously. Spot on, too.

I’ve honestly got no clue. The only thing that has changed is I don’t have the 10/20V selection switch wired in right now. I wonder if that’s somehow bad? Hmmm.

Or maybe something was messed up with the offset circuit? I un-soldered the adjustment pot, so maybe it was somehow shorting and all this fiddling has fixed it? Without the zero adjust pot even connected, I’m only getting -300uV of offset, which that LT1097 should have easily been able to null out. So, something weird is going on. (Hooking the pot back up with the OP-05 and I’m able get it down to around 5uV of offset.)

This one is truly baffling.

Well, it's clear that the laws of physics stop at the door to your house  ;) . Well, except for the ones involved in frying parts that is :palm: . It's safe to say we've all been there - on both counts.

On a more serious note, I am beginning to strongly believe in the modified adage: Measure twice, replace once - don't assume anything when repairing electronics... Sometimes, eroded solder joints, bad cable connections, misbehaving pots, switches and op-amps, etc..., can lead to the most bizarre circuit behaviors.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 02:40:32 pm
I know, right? ROFL

My big problem with part frying is my desk is so cramped and I have no real storage for stuff. That's being rectified this week however as I'll finally have all my stuff unpacked, shelves up and a real lab workspace setup.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 09, 2014, 03:42:18 pm
OK, the 2020B not putting out the amps it should was due to a bad measurement cable on my part  :palm: . Anyways, with that out of the way I have only one remaining issue after fully calibrating it:

The V/A selector switch makes a poor contact when set to show Amps. I have to wiggle the switch a bit before the current measurement shows on the meter. Is it possible to take this toggle switch apart and clean it or do I need to order a replacement?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 06:37:03 pm
You can get some DeOXIT inside via the back and shaft. Spray some in and toggle it a bunch.

Otherwise it's just a small DPDT switch (ON-ON not ON-OFF-ON).


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 09, 2014, 08:40:25 pm
Hey timb -

One of my friends who is an engineer that has done some work on HVAC products had a great suggestion for a low-impact way to PWM the heater circuit. The idea is actually a very common approach and I'm sort of embarrassed not to have thought of it myself.

The approach is this: Use the unrectified secondary output (AC) to power the heater. The PWM control is via something that only switches on/off near the zero crossing (ZC). Since the heater is wound in a way to be mostly resistive, this can just be a simple solid-state relay with a ZC feature, or a opto-triac + triac. To control the power accurately, you need a zero crossing detector input to the micro. There are many circuits for this out there, but it's fairly simple to build one with an optocoupler and a few discrete components. Then in the micro, you turn om the SSR, count the on pulses of the ZC detector, turn off the SSR, count the off pulses, etc.

If you decide to go this route, read the SSR data sheet carefully. One of the "gotchas" I found when perusing data sheets is that many of the zero-crossing SSR either don't specify or specify very high zero-cross turn-on voltages. Since most of these things are meant to switch 120 or 240V mains, switching on at 20V isn't a big deal for many purposes. However, I've got a 48V AC signal, so switching on at 20V is a big deal. The units I order have a typical turn-on voltage of 2V, and a max of 5V, so that's at least a little better.

This is the ssr I ordered:

http://www.clare.com/home/pdfs.nsf/0/B76903D991990B0885256A2C006BB7A7/ (http://www.clare.com/home/pdfs.nsf/0/B76903D991990B0885256A2C006BB7A7/)$file/Ps1201.pdf

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 08:43:17 pm
Interesting, I just got in an SSR and was thinking of doing what you said, only directly off the 120VAC mains heater input and not the transformer secondary.

Can you see a downside to this?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 09, 2014, 08:47:27 pm
Interesting, I just got in an SSR and was thinking of doing what you said, only directly off the 120VAC mains heater input and not the transformer secondary.

Can you see a downside to this?


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I think this is exactly what the original circuit in my 2005A did. I remember there was a circuit attached to the SCR, and I played around with it in LT SPice a bit, and I believe it's basically a circuit to limit turn-on to near the ZC point (the SCR handles the turn-off at ZC automatically, as that's how they work).

The only downside is you're messing with A/C mains voltage with all the associated safety concerns. Oh, and also you'll obviously need significantly more wire, probably need a resistance around the 1500 ohms of the original circuit.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 09, 2014, 09:28:53 pm
This path may lead to destroying the ultra low ripple of these units. All this pwm heater stuff may be reflected in the output :(
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 09, 2014, 09:29:49 pm
This path may lead to destroying the ultra low ripple of these units. All this pwm heater stuff may be reflected in the output :(

go read the other thread. That' what all the discussion is about :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on November 09, 2014, 11:17:25 pm
You can get some DeOXIT inside via the back and shaft. Spray some in and toggle it a bunch.

Otherwise it's just a small DPDT switch (ON-ON not ON-OFF-ON).


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Anything selling on e-bay that might match?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 11:25:43 pm
Interesting, I just got in an SSR and was thinking of doing what you said, only directly off the 120VAC mains heater input and not the transformer secondary.

Can you see a downside to this?


Sent from my Smartphone

I think this is exactly what the original circuit in my 2005A did. I remember there was a circuit attached to the SCR, and I played around with it in LT SPice a bit, and I believe it's basically a circuit to limit turn-on to near the ZC point (the SCR handles the turn-off at ZC automatically, as that's how they work).

The only downside is you're messing with A/C mains voltage with all the associated safety concerns. Oh, and also you'll obviously need significantly more wire, probably need a resistance around the 1500 ohms of the original circuit.

That’s interesting. I was wondering about the SCR.

Here’s my results from iCircuit:

(http://img.timb.us/2005A_On_Pos.png)

(http://img.timb.us/2005A_On_Neg.png)

(http://img.timb.us/2005A_Off_Pos.png)

(http://img.timb.us/2005A_Off_Neg.png)

iCircuit: 2005_Thermostat.cir (http://img.timb.us/2005_Thermostat.cir)

I thought they were just using the SCR so the thermostat didn’t have to handle any current.

Anyway, I’m comfortable with 120VAC and don’t mind if I’m using an SSR anyway.

On my 2005, I’m rebuilding the heater coil and need a new thermostat, so my plan was to simply use one of those thermostat ICs and an SSR. I’ve found one that can do 1c of hysteresis which is a lot better than the 10c of the original. I was also going to add one of those small pill shaped bi-metal thermostats set at, say, 85c as an emergency shutoff. I might just wire it inline or have it trip a resettable fuse so the user is aware. (Most likely the latter.)

This unit is for resale, so I’m just looking for a simple, reliable option that will last.

Now, on the 2005A, doing PWM with an SSR is looking like a very viable option.

By the way, I know this is a PD thread, but I thought I’d share some pictures of a heated zener reference from a card in my Fluke 382A Calibrator:

(http://img.timb.us/Fluke_Ref_1.jpg)

(http://img.timb.us/Fluke_Ref_2.jpg)

(http://img.timb.us/Fluke_Ref_3.jpg)

The two power resistors on top heat the metal casing with a thermostatic cutoff in-between them, there’s also a diode buried inside the metal that acts as a temperature sensor I think (black wires going INTO the metal frame in picture two). Interesting setup.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 09, 2014, 11:26:18 pm
You can get some DeOXIT inside via the back and shaft. Spray some in and toggle it a bunch.

Otherwise it's just a small DPDT switch (ON-ON not ON-OFF-ON).


Sent from my Smartphone

Anything selling on e-bay that might match?

I’ll find a suitable match for you, give me a few.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 10, 2014, 02:23:47 am
WoW, that Fluke reference is an exotic looking thing!  I worked on cleaning up the 5020 over the weekend, the top facing side of the supply with the trace side of the board and switches was pretty dirty and grime covered with everything able to flow right down in there.  They cleaned up good.  I cleaned up the component side of the board also, all the IC's look to be dated around mid-1984.  C1, 3, 5 and 34 are out for replacement.  This thing looks to be in pretty good overall shape. 

(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/560215_867612513258650_2386621394675915075_n.jpg?oh=e8d1d24d4bcd1904158ad00fef6bbb92&oe=54E0BA6C&__gda__=1428070289_a5c5c94648fac31da2a16bfcee511d8f)

(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-xfa1/v/t1.0-9/10603246_867613399925228_7183467999609467278_n.jpg?oh=ec5ce0f411590b5b62d6cfccc8e796b4&oe=551F761D&__gda__=1423034155_3e82e5be9760a715b89196ca59cdcb97)

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 10, 2014, 02:35:59 am
I think this is exactly what the original circuit in my 2005A did. I remember there was a circuit attached to the SCR, and I played around with it in LT SPice a bit, and I believe it's basically a circuit to limit turn-on to near the ZC point (the SCR handles the turn-off at ZC automatically, as that's how they work).

I took a detailed look at the circuit and agree.  I wonder why they only used half-wave power.  I assume the heater is shielded well enough from the reference not to couple low frequency noise.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 10, 2014, 03:05:31 am
timb -

I went over this before, but maybe you missed it. I already made a thermostat that you can set the hysteresis to whatever value you want (currently set to around 0.6C). However, that won't get you temperature regulation to within 1C. The problem is, when the thermostat shuts off, a big load of heat has already been transferred from the heater coil to the metal of the tube. This heat continues to soak in, and the heat within the tube continues to rise. I don't recall the exact numbers, but it was very significant - way more than the 1C.

There are at least two ways to fix this: 1)lower the thermal "mass". 2) Introduce a control system that takes this into account and which manages the heat on/off cycles to reach some sort of steady state. That's the whole point of the PID controller, but there are other circuits that will work.

Robrenz - Regarding the PWM, the current plan is for the "PWM" to be very long cycles, and for the on/off transitions to be at or near zero crossings on the AC waveform. I am 100% positive if I ran that off the AC mains, they would be indistinguishable from the original circuit in terms of the disruption they add to the output voltage. And I think even running them off the secondary voltage, the same one powering the output regulator, it's not going to cause issues. I say this because I already have my replacement heater and thermostat running that way, and although I do see fluctuation in the output (but still < 100uV), it is correlated with the overall heat cycle, not the point where the heater turns on/off.

Anyway, that's my theory, and we'll see how it works out if I can ever get my oscilloscope back from Rigol and that nichrome wire that Tim submitted to the black hole that is the US Postal Service.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 10, 2014, 03:16:53 am
Why not just use a linear control loop?  It is not like you can get better efficiency with pulse width modulation.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ManateeMafia on November 10, 2014, 05:00:45 am
Is the linear control loop the same as a proportional control loop like the one used in the Fluke 732A? The thermal mass of the 732A seems comparatively large but they can maintain it at +/- 2 deg C.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 10, 2014, 05:44:05 am
Yes, it is pretty much a PID with just the P. But without PWM, it means you are dissapating the excess heater power in some transistor.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on November 10, 2014, 05:55:54 am
Is the linear control loop the same as a proportional control loop like the one used in the Fluke 732A? The thermal mass of the 732A seems comparatively large but they can maintain it at +/- 2 deg C.

I was not thinking of the Fluke 732A specifically but that is the type of implementation I had in mind.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 10, 2014, 06:05:38 am
timb -

I went over this before, but maybe you missed it. I already made a thermostat that you can set the hysteresis to whatever value you want (currently set to around 0.6C). However, that won't get you temperature regulation to within 1C. The problem is, when the thermostat shuts off, a big load of heat has already been transferred from the heater coil to the metal of the tube. This heat continues to soak in, and the heat within the tube continues to rise. I don't recall the exact numbers, but it was very significant - way more than the 1C.

Right, but the bi-metal thermostats originally used had 10c of hysteresis, so an IC with 1c (or hell, even 3c which is a common option) would be better than what was on there, right?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 10, 2014, 07:00:37 am
timb -

I went over this before, but maybe you missed it. I already made a thermostat that you can set the hysteresis to whatever value you want (currently set to around 0.6C). However, that won't get you temperature regulation to within 1C. The problem is, when the thermostat shuts off, a big load of heat has already been transferred from the heater coil to the metal of the tube. This heat continues to soak in, and the heat within the tube continues to rise. I don't recall the exact numbers, but it was very significant - way more than the 1C.

Right, but the bi-metal thermostats originally used had 10c of hysteresis, so an IC with 1c (or hell, even 3c which is a common option) would be better than what was on there, right?

Oh, yes definitely. I think I was seeing about 5C of drift with mine. And as you established earlier, I am running it at too high a power,so it should be somewhat better than that running at a more reasonable 6W or so.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 11, 2014, 03:25:55 am
timb -

Here's some simulation results with the LTSpice model created for the original heater thermostat with SCR circuit. An image of the schematic and the LTSpice model are also attached.

The top trace is the AC mains voltage so you can see the relative position of the waveforms in the lower window. The green waveform is the voltage controlling the simulated thermostat cycle. I'm using a voltage controlled switch to model that, so -1V corresponds to an OFF thermostat, and +1V corresponds to thermostat ON. I've deliberately picked timing on that so we can see what happens when it turns on and off in the middle of a cycle. The pink waveform is the current through the heater.

You can see that it largely limits turn on to a zero crossing (there's a little spike because the circuit isn't perfect). The turn-off is restricted to a zero crossing by the behavior of the SCR.

And BTW, if you think the schematic looks sloppy, it's because I was trying to duplicate it exactly as it was drawn on the PD2005A schematic.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 11, 2014, 02:11:43 pm
I put the new caps in my 5020 and it all looks to work at least as well as PD intended it to, I’m very pleased with it.  It’s fairly stable right from the get-go.  After about an hour under moderate load I calibrated it using a 3456A.  The dial settings are all considerably more accurate than the .1% +/- .5 mV at any set point, and after running for 10 hours under a 500 mA load overnight it didn’t drift more than the .001% tolerance.  So I’m satisfied that it’s within specs and I can trust it for reliable use. 

I ran in to the same problem with the front panel Timb did.  After removing all the old calibration stickers, there was no way on earth to remove the markings left behind.  I think PD used some type of varnish on the aluminum that gets a yellowish tint to it over time, and it came off with the stickers.  My answer to this will be…. if you could guess.....  a new set of calibration stickers from work to cover the old ugly spots- creative LOL.  I’ll post a pix later after I get a chance to paint the outside cabinet for laughs. 

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 11, 2014, 02:16:49 pm
I have never had a Power Designs front panel that would not clean up completely when using a magic sponge (melamine foam) and IPA.  They really are magic.

Check out the before and after pics of the top rail on my 3410A restoration (https://www.eevblog.com/forum/testgear/hp-3410a-ac-microvoltmeter-restoration/msg433969/#msg433969).  That was not repainted, just a magic sponge.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 11, 2014, 02:27:43 pm
I have never had a Power Designs front panel that would not clean up completely when using a magic sponge (melamine foam) and IPA.  They really are magic.

I scrubbed the thing to death with a magic eraser (melamine) and 97% IPA. I also tried a mix of 30% peroxide, baking soda, tetraacetylethylenediamine and sodium percarbonate, with a little Dawn liquid dish soap. Still nothing.

I might try to use the peroxide, TAED and PCS I used above, but in a gel form and leave it in the sun for a few hours (UV exposure). [AKA retr0br1ght]


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 11, 2014, 02:31:02 pm
All my other PD power supply aluminum fronts cleaned up well, just not this one.  Any amount more of cleaning just polishes the aluminum where the old stickers were to a shine.  All the old, "lab cigarette tar," came off the rest of the front, but there is definitely some type of varnish or coating there that I don't want to rub through.  I figure I'll just play it safe rather than risk ruining it.

I have plenty of different cal stickers to use.  They are all decent laminated ones too.  It is sort of legitimately calibrated  ;)

-Mark-
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 11, 2014, 02:35:09 pm
Mark, I'll try a few more chemical agents and see what I can come up with. You're right though, there is a varnish on there. I can see a brownish/dirty looking area several places that won't come off. I think this is the varnish or coating that has aged from UV over the years.

Worst case I destroy my panel and have a new one made. I'm milling this one out anyway for a new panel meter.


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 11, 2014, 02:39:11 pm
I found a few stickers to use in the meantime- "Periodic Calibration Not Required," and, "For Reference Only."  That way I keep it honest  :-DD  It's sort of a shame because the panel cleaned up so nice other than where those old stickers were.

I'll let it be a lesson to myself if I ever get another one of these in the future...  leave old patina in place.

The other misfortune is PD didn't etch this front panel, the legends are just printed on.  Otherwise I would buff it out down to bare aluminum.  The panels on my 3650S PD supplies are the only ones I have ran across from PD that have the legends etched in.     

-Mark-
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 11, 2014, 02:43:03 pm
timb -

Here's some simulation results with the LTSpice model created for the original heater thermostat with SCR circuit. An image of the schematic and the LTSpice model are also attached.

The top trace is the AC mains voltage so you can see the relative position of the waveforms in the lower window. The green waveform is the voltage controlling the simulated thermostat cycle. I'm using a voltage controlled switch to model that, so -1V corresponds to an OFF thermostat, and +1V corresponds to thermostat ON. I've deliberately picked timing on that so we can see what happens when it turns on and off in the middle of a cycle. The pink waveform is the current through the heater.

You can see that it largely limits turn on to a zero crossing (there's a little spike because the circuit isn't perfect). The turn-off is restricted to a zero crossing by the behavior of the SCR.

And BTW, if you think the schematic looks sloppy, it's because I was trying to duplicate it exactly as it was drawn on the PD2005A schematic.

Interesting... I just added some scope meter measurements to my iCircuit simulation and got the same thing. I bet they did this to prevent interference from the thermostat switch. I have another PD supply with a working oven based on the 2005 design (100V model) and I can see a large transient on the regulated output when the heater turns on and off.

The switch may also spark, because a pair of nearby speakers make a popping noise as well.

Switching at zero crossing would prevent this.

I guess that NPN in the circuit is there to bias the SCR low when the thermostat is off?

Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 11, 2014, 04:58:27 pm
Interesting... I just added some scope meter measurements to my iCircuit simulation and got the same thing. I bet they did this to prevent interference from the thermostat switch. I have another PD supply with a working oven based on the 2005 design (100V model) and I can see a large transient on the regulated output when the heater turns on and off.

The switch may also spark, because a pair of nearby speakers make a popping noise as well.

Switching at zero crossing would prevent this.

Yes, this is the usual reason for switching at the zero crossing level; it reduces generated EMI.

I guess that NPN in the circuit is there to bias the SCR low when the thermostat is off?

It pulls the gate of the SCR low when the half-wave rectified mains voltage exceeds 21 volts. This gives enough of a pulse to turn on the SCR, but only near the start of the voltage ramp-up.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 11, 2014, 09:32:35 pm
I see. Makes more sense now. I couldn't see that happening in my simulation and haven't gotten to a PC to load up the LTSpice one.


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Luap2 on November 12, 2014, 10:31:26 pm
I have been a reader of this forum for a year of so, lots of info here and a lots of it over my head. This thread got me to buy a 6050a off Ebay.
Like the few pieces HP equipment I have the in sides are a pleasure to look at. On to the 6050a I works ok. However  I have measured 47v across the 40v cap. I have the info that was posted in this thread ( thank you to those that did it )but I need more. I would like some service info to run this down  I do not mind buying it, but would like to do a PDF down load and not pay for the manual to be sent to Alaska. I have looked and all I find is a bound manual  to be shipped. Any one know where on the web I can do a PDF down Load, thanks in advance

  Luap2   
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 12, 2014, 10:36:27 pm
I have been a reader of this forum for a year of so, lots of info here and a lots of it over my head. This thread got me to buy a 6050a off Ebay.
Like the few pieces HP equipment I have the in sides are a pleasure to look at. On to the 6050a I works ok. However  I have measured 47v across the 40v cap. I have the info that was posted in this thread ( thank you to those that did it )but I need more. I would like some service info to run this down  I do not mind buying it, but would like to do a PDF down load and not pay for the manual to be sent to Alaska. I have looked and all I find is a bound manual  to be shipped. Any one know where on the web I can do a PDF down Load, thanks in advance

  Luap2   

Not sure about 6050A. I see a link to a manual for a TW6050D here:

http://www.ko4bb.com/manuals/index.php?dir=09)_Misc_Test_Equipment/Power_Designs (http://www.ko4bb.com/manuals/index.php?dir=09)_Misc_Test_Equipment/Power_Designs)

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 12, 2014, 10:48:37 pm
So I got the 2020B all wired back up last night.

I did something a bit different with the 10-20V selection switch. PD had it so that by default the output wire (blue) came directly out of the 10k resistor on the back of the switch board. When you had the switch set to 10V, there were two wires that connected to each end of the resistor and it would short it.

The problem with this approach is that the 10V range would pick up an extra 0.5Ohm from the switch.

So when I rewired it, I hooked the blue output lead to the center of the switch and connected the 10V contact to the top of the 10k resistor (where the output of the switch bank cones in) and the 20V switch contact to the output of the 10k resistor. This way both ranges have the same added resistance.

(http://tapatalk.imageshack.com/v2/14/11/12/0d54b4b5d008f2a6e8c8a9e9e9151fee.jpg)

(http://tapatalk.imageshack.com/v2/14/11/12/f5a842bcd3c3fa4ffca1c1aea417733c.jpg)

(http://tapatalk.imageshack.com/v2/14/11/12/6aa8249051d619daebe30e8488f23edc.jpg)

I got the calibration spot on from 1V to 20V!.. Well, until I hooked up the indicator lamps. As soon as I did that, I started getting weird drift from 20V down. If I calibrate for 20.0000V, I'll be at 1.996xxxV at the bottom.

I think the HVDC going through the same switch is introducing something into the range selection output.


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 13, 2014, 10:05:00 am
Tonight I realized I had a small issue with my 2005 heater rebuild. It seems that the thermostat module is what physically presses against the bottom of the ref board socket to hold it against the ring. With the OEM thermostat now gone, I had to find another solution. Enter my friend: JB

A little JB Weld and the socket is now permanently apart of the mounting ring. Huzzah!

(http://tapatalk.imageshack.com/v2/14/11/13/dff1019cc43af79b43f643308a370db9.jpg)

(http://tapatalk.imageshack.com/v2/14/11/13/7ab436bdbf89167edf5c7f6031e466f8.jpg)

Since the socket sticks out a bit from the top of the ring, I couldn't just straight up clamp it. I needed a tube that only touched the edges of the ring... Now I remember why I save pill bottles! (Aside from being handy for parts storage, they're great for stuff like this.)

(http://tapatalk.imageshack.com/v2/14/11/13/0df353e9e8fad6eec1eca057e5332d1e.jpg)


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 15, 2014, 06:23:09 am
So, I got another PD supply in! This one isn’t a precision unit and in fact appears to have been made in the early 90’s, surely one of the last units they made. Here’s the odd thing though, some of the parts date back to the mid-1970’s! I’ve noticed this is some of their precision supplies as well; since they had custom binned parts, I think they kept quite a stock on hand.

They also appear to be using Illinois Capacitor [ic] brand caps, which I had honestly never heard of until I googled them, but turns out they have been around since the 1930’s and hold quite a few important patents on high temperature electrolytes. That said, I’m not certain of their quality.

Overall the construction seems fairly good; I don’t see any glaring safety issues. They’re still even using turret boards! The one thing that does bother me is the fact that the main boards are only secured halfway up. There’s a bracket that attaches to the back of the unit, which in turn extends half the length of the main PCBs on both sides, which they’re screwed into. The remaining length of PCB is just hanging there; I can touch it and make it flex, which seems not optimal.

After inspecting the insides and doing some basic tests, I decided to do a full load test. Out of the box, without tweaking any adjustment pots, I set each source to 5.00A and hooked the outputs directly to two of my 5.5 digit multimeters (which have been calibrated against a transfer standard recently) set to the 10A range. You can see the results for yourself:

(http://img.timb.us/TW6050D_0.jpg)

The Keithley 197A is connected to Source B; the Tek DMM4020 is hooked to Source A. This is after running for 10 minutes or so. I let it run for an hour (with banana shunts, not through my meters) and nothing got over temperature. I also set the max current adjust pots up to 6.5A (the unit is rated for 5A@0-6V or 1A@0-60V max) and ran it for another 15 minutes; I only saw a 10c rise in the series pass transistors, but it stayed in regulation, so I’d say they’ve got appropriate derating on all the parts.

The unit is physically split into two identical power supplies, completely isolated from each other. Source A is the top board, Source B is the bottom board. The transformer is pretty big with eight secondaries (four for each source), six of which are center tapped.

Anyway, enough talk, here’s some pictures!


(http://img.timb.us/TW6050D_1.jpg)

(http://img.timb.us/TW6050D_2.jpg)

(http://img.timb.us/TW6050D_3.jpg)

(http://img.timb.us/TW6050D_4.jpg)

(http://img.timb.us/TW6050D_5.jpg)

(http://img.timb.us/TW6050D_6.jpg)

(http://img.timb.us/TW6050D_7.jpg)

(http://img.timb.us/TW6050D_8.jpg)

(http://img.timb.us/TW6050D_9.jpg)

(http://img.timb.us/TW6050D_10.jpg)

(http://img.timb.us/TW6050D_11.jpg)

(http://img.timb.us/TW6050D_12.jpg)

(http://img.timb.us/TW6050D_13.jpg)

(http://img.timb.us/TW6050D_14.jpg)

(http://img.timb.us/TW6050D_15.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 15, 2014, 06:39:21 am
That's pretty cool. I didn't know they had supplies like that. I think you qualify as an official Power Designs addict at this point. How many of these things do you have now?

Fortunately, space constraints on my lab bench limit me from acquiring any more :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 15, 2014, 07:15:11 am
That's pretty cool. I didn't know they had supplies like that. I think you qualify as an official Power Designs addict at this point. How many of these things do you have now?

Fortunately, space constraints on my lab bench limit me from acquiring any more :)

Five…with a sixth on the way! (http://img.timb.us/emoticon/science.gif)

Honestly, I do plan on reselling most of these. I’m buying broken ones off eBay to fix up and give new homes to, rather than seeing them end up in a scrap yard.

I’m keeping the TW6050D I just posted, plus the 2020B I’ve been working my ass off to fix.

I’d also like to build a sort of oven restoration kit to sell on eBay, so people can modernize the oven and keep them going. But we’ll see how my own attempts go on this 2005.

Life’s been pretty stressful lately due to a family member with some medical issues and my addict cousin staying with me while he gets clean, so working on these at night gives me some “zen” time.

Anyway, I did get the 2020B case repainted, and it came out pretty great I think!

(http://img.timb.us/PD2020B_Case.jpg)

(http://img.timb.us/PD2020B_Repaint.jpg)

I also snapped a picture of three other cases together (with the original paint) to show the slight color variations:

(http://img.timb.us/PD_Colors.jpg)

It’s interesting to note that the 2005A is about 0.5” longer than the 2005; so they obviously used an entirely different frame. My 1025P was produced in ’67 judging by the caps, while my 2005 has a ’65 date on the oven; meanwhile my 2005A has ’73 stamped on the upper lefthand corner of the from panel’s backside. According to the official 2005 schematics, it would have entered production in ’65; the 2005A schematics are dated ’69 so that would most likely mean early 1970 for the first production run. I can’t find schematics for the 1025P, but it’s constructed like the 2005 (all point to point wiring) so I’d say 1967 is a good bet for initial production. Why am I saying all this? Well, if you look at the 2005’s top cover, you’ll notice it only has a couple of vent slots, meanwhile the 1025P has the hole pattern they used for all the other precision supplies. However, the 1025P and 2005 both have the circular indents, which were intended for stacking the supplies onto of one another; the 2005A omits this. Why?

Well the 2005 and 1025P both included circular rubber feet that simply screwed into the bottom covers, the 2005A on the other hand included molded plastic feet with a metal tilting bail; this setup appears to have been used on all of the following precision supplies (including my 2020B).

Speaking of the bottoms of these supplies, one final curious point: The 2005 and 2005A both used non-painted metal bottom panels, however, the 1025P (which chronological came in-between the two aforementioned supplies) had a painted metal bottom panel, with the same normal hole pattern as the top. This was also the way all future supplies would be constructed, except the 2005A.

I know none of this matters, but for some reason Power Designs really fascinates me. I wish I could find someone who worked at the company for a long time to interview. Companies that produced lab equipment in the 1960’s were constantly popping up and going out of business. There’s a few great articles about multimeters that talk about it. The history of calculators from about 1950 to 1990 is very interesting as well. The ’70s saw an explosion in the production of calculators; it went from huge mechanical desktop adding machines, to solid state, to pocket calculators to personal computers. Okay, I’m rambling now, sorry.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MarkPalmer on November 15, 2014, 07:03:37 pm
I enjoyed the photos of the TW6050.  Funny you mention the history of calculators, as that's one of my biggest electronic fascinations- vintage USA made calculators and computers.  I have quite a few early Bowmar, Commodore, Novus, and HP calculators and enjoy fussing around with them.  Other than HP's most vintage calculators can be found dirt cheap.  MY HPIB instrument system works through an HP 85 computer, just as it would have been used in the 1980's and I can actually program it, still remembering BASIC from high school. 

Here are the power supplies I use on my workbenches.  TW5005, 3650S (X2), 5020 (new to me), and 1556 HV, a LKB 2500V/250mA modified electrophoresis supply is on top of it.  I have a few small HP supplies on the shelf.  I just respect Power designs as an American company that (until bought out) didn’t seem to ever compromise their quality principles.  These bench supplies are extremely reliable and I’m sure mine will still function for many generations after I am gone.  There is something much more satisfying in using these supplies along with my other 70’s and 80’s vintage lab grade equipment in comparison to this white plastic with Playskool rubber bumper crap that is made today, much of which only runs a few years until meddled with issues that can’t be resolved in a realistic manner.  My PD supplies I trust and I don’t worry about- when I turn them on to use them, they always work as they should.  And hey, they are cheap enough on E-bay where even too many of them doesn’t set you back much.   :blah:

(https://scontent-a-iad.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/1385751_870523686300866_4916830783204302136_n.jpg?oh=ee18d5da162b9321733743613cef6114&oe=54DD22D2)

(https://scontent-b-iad.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/1236178_870521466301088_8966436301138954633_n.jpg?oh=4326ae3a0965ee3b44a139e061f5a20b&oe=54E8EE9A)

(https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-9/p526x296/10304427_870521049634463_652657346145393042_n.jpg?oh=fd9d98191b0e006f9dff442f9d46eb34&oe=54E55CA6&__gda__=1423709652_0b747a88544f7658714bf3baa7193770)

-Mark-

 

Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 16, 2014, 06:35:24 am
Wow, that’s awesome! I really want one of those HV units.

So, I got the 2020B all buttoned up. I ended up putting an LT1001 in there, which basically has no drift compared to the OP-02 *and* it has a 4mV offset. So this is basically the highest Op-Amp upgrade you can get. The next down would be the OP-177.

(http://img.timb.us/PD2020B_LT1001.jpg)

(http://img.timb.us/PD2020B_Complete1.jpg)

(http://img.timb.us/PD2020B_Complete2.jpg)

I ended up replacing all the electrolytics, every transistor, both Op-Amps and all the power resistors; taking every pot physically apart, cleaning, re-lubricating (Silicone or White Lithium Grease) and applying DeOXIT Gold or Shield to the contacts. Even the "sealed" Helipots used for zero and cal got the treatment (you can use super glue to reapply the bottom cap afterwards).

The only thing left to do is build a replacement meter. It's either going to be some sort of an LED bargraph or perhaps an Intersil 3.5 Digit LED driving DMM-in-a-chip. (Maxim make newer versions that are Delta Sigma, requiring few external components and can do 4.5 digits.)

Of course I'd use two of those adorable HP four digit 7-segment bubble displays to display voltage and current at the same time. Simply use the mounting holes from the old panel meter with short standoffs to hold the board and get a piece of red acrylic cut to fit into the existing cutout with a bit of glue.


Anyway, the new color looks amazing.

(http://img.timb.us/PD2020B_Complete3.jpg)

(http://img.timb.us/PD2020B_Complete4.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on November 16, 2014, 02:18:17 pm
What a great job you did, timb  :clap:

I was surprised by how out of shape your unit was and how you've brought it back to life, and looking forward to seeing your upgrades.

I'd be curious to see whether the panel meters will inject a tiny bit of noise into the output if you build it into the chassis. 

I'm like MarkPalmer on maintaining the original look and technology as much as possible, and when I do need better metering of the power output, just drop my eload in series or use separate DMMs. 

I've kept original labels from the primary owner whenever possible [ not the seller].  The top one was from Boeing, and one of the others is either Martin Marietta, or Grumman but fell off, and one from a cal lab that has stickers on the screws not to open it  ;).  Aside from cleaning and some Dexoit, the units are working as they came OOB from eBay.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 16, 2014, 02:25:38 pm
Agreed! very nice job  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 17, 2014, 08:04:08 am
What a great job you did, timb  :clap:

I was surprised by how out of shape your unit was and how you've brought it back to life, and looking forward to seeing your upgrades.

I'd be curious to see whether the panel meters will inject a tiny bit of noise into the output if you build it into the chassis. 

I'm like MarkPalmer on maintaining the original look and technology as much as possible, and when I do need better metering of the power output, just drop my eload in series or use separate DMMs. 

I've kept original labels from the primary owner whenever possible [ not the seller].  The top one was from Boeing, and one of the others is either Martin Marietta, or Grumman but fell off, and one from a cal lab that has stickers on the screws not to open it  ;).  Aside from cleaning and some Dexoit, the units are working as they came OOB from eBay.

Agreed! very nice job  :-+

Thanks guys! Yeah, I worked hard on this one and I appreciate all the help from everyone here. Physically, I would have *liked* to keep this 2020B stock, but the panel meter was broken beyond repair and I haven’t been able to locate a suitable replacement edgewise meter, so I figure doing some sort of retro looking digital meter would be my best bet.

That’s why I was thinking of using the HP bubble displays, to keep it from the same era:

(http://img.timb.us/hp-bub1.jpg)

(http://img.timb.us/hp-bub2.jpg)

As for noise, I doubt it will inject any noise. I can always use an Op-Amp on the input of the panel meter chip so I don’t place any load on the output itself (though I imagine that’s already part of the chip). I can also use one of those cheap 5V supply isolators to power the chip if I do see any noise. I highly doubt that will be an issue though.

I also did consider rebuilding the old meter with a Switec X27.168 servo, which could have been cool.

The other option is using tiny individual LEDs on a board to make a custom bar graph type deal. I’d custom print markings on translucent vinyl and place it in-front of the LEDs and behind a clear piece of acrylic glass in the meter cutout.

Not sure what would look the best, though I’m going with the LEDs.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 18, 2014, 09:33:41 am
Okay, tonight I started breadboarding the 2005A replacement reference. I'm starting out without the LM399 and just using a generic 6.2V Zener for testing.

I'm basically following the circuit as-is, just using a MAT01 to see how it functions. My resistor values are closest-match and I'm using a 2N2222A as the other transistor. I think I've got a 1N4007 where the only non-Zener (a "GI44") is.

I tried desoldering one leg of that diode from my working board and, while trying to unwrap the lead, the diode literally split in half. So I can't characterize what they had in there.

I guess spending close to 40 years in a 75c oven will make anything brittle!

Anyway, I'll have results tonight!

(http://tapatalk.imageshack.com/v2/14/11/18/1e149dbc86d662d02970a2e953116659.jpg)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 18, 2014, 06:36:52 pm
Very nice! I was wondering who bought that TW6050D ;)  Glad it went to a good home. As for the display mod, that will be a very nice upgrade!   :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 18, 2014, 07:56:31 pm

Very nice! I was wondering who bought that TW6050D ;)  Glad it went to a good home. As for the display mod, that will be a very nice upgrade!   :-+

Were you the seller or just watching it?


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 18, 2014, 08:49:10 pm
Just a creepy watcher ;). Although i had thought to buy it a couple of relists before, but the seller creeped me out with the way he described the shipping to me in answer to a question on shipping cost.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 18, 2014, 10:11:06 pm
Haha, what was his description?

I ended up getting it for $100 shipped. After shipping he told me it ended up costing him just over $50 to ship it, so he lost out on the deal but wasn't mad, as that's the way it goes sometimes.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 18, 2014, 11:02:38 pm
Yeah, he gave me a similar story... I put a best offer of 80$ on it (and he had listed shipping as 45$), and countered 120$ saying that he had to cover shipping... I refused the counter offer and messaged him that I was under the impression that the shipping was aside from the offer/bid/BIN price. Just weird. But glad you got it... I love my 6050D ;D  (and my 6050C that I modded the display to larger 7-segment modules).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 19, 2014, 12:13:29 am
Oh post pictures of that 6050C!

Personally, I doubt shipping cost $50. I had a Fluke 382A shipped for $30 which is about double the length of the TW6060D and weighs 60lbs. I also had an HP3456A ship for $19.

Those were from professional sellers though. Maybe this was $50 if the guy took it to the UPS Store and had them pack it?

Either way, not my problem. I figure I got a good deal on this. It fits in a nice gap between my Keithley 2200-30-3 and my 2020B. (And other smaller things like my HP6235A which is GREAT for analog work since it has a tracking negative rail.)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 19, 2014, 11:26:45 am
Oh post pictures of that 6050C!

I already did! ;)   But in the Projects area...  https://www.eevblog.com/forum/projects/power-designs-6050c-display-mod/msg535294/#msg535294 (https://www.eevblog.com/forum/projects/power-designs-6050c-display-mod/msg535294/#msg535294)

Perhaps this will get it some more view loving ;)
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 19, 2014, 01:01:33 pm
Sweet! I'll have a look. So, #6 arrived today in absolutely gorgeous shape. Everything works a treat and it seemed to be perfectly in cal, too. The dust inside has been undisturbed for quite some time, so I'd say it hasn't been messed with recently. What is it?

Power Designs Model 4010

(http://tapatalk.imageshack.com/v2/14/11/19/da8a36e23016a3ac1a56a6f7ed291c92.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/870f0d9bc9451d3bd335b11c390e1c2e.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/cb70e3d39448be234ab3eab22a250ebd.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/c60557d1aa40c7b71cb6120e5265cdf2.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/4024e30c816889afb66207c645da2013.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/7a0f21697744117b046eff7c5e753e15.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/67a56c6eff1ebbc82fc4e7b0907d89cf.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/1c6bab9711fb009cfbadb7e2fa5d0163.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/aff2823ad64cf17d9b966140f6a3f054.jpg)

(http://tapatalk.imageshack.com/v2/14/11/19/be00120142efa485e03847d2f3b6684f.jpg)

Dates from about 1967 so far as I can tell. It uses the exact same reference oven as the 2005A (down to the model number) but is constructed like the 2005. The cover also was painted in a totally different shade of blue than any other PD supply I've seen.

I like the funky square resistors too.

Even the original neon lamps work... This is the best looking supply I've received to date. Just wish I could get the schematics for it.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 19, 2014, 01:11:13 pm
Damnit!  I was watching that one TOO.  But I really couldn't talk myself into buying it.   |O   Damn conscience.
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 19, 2014, 01:18:40 pm
Any others you're watching? XD

It's really accurate, too. At full load (40V@1A) I was seeing basically no ripple and very little noise. Short term stability is on par with my 2020B; though I'm sure the 24H specs won't be. Once I clean and lube everything it should make a good supply.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 19, 2014, 01:27:18 pm
At the other end of the range, I was looking at this beauty:  eBay auction: #381047047785.  And then of course, there is my new favourite eBay auction: #121171745722 (although the shipping is 84$  :o )
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 19, 2014, 01:35:13 pm
Yeah, I'd like one of those kV supplies as well. BTW, if you're interested in the 4010 let me know. I'm open to trades for other equipment. I'm currently looking for a DC load, PD supplies, bi-polar operational supplies and anything interesting or unique.


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 19, 2014, 01:39:24 pm
Well, I do have this zooming in my direction: eBay auction: #201218241093  No idea what the operational status is of it yet.  And I will probably get violated in all holes by UPS when it shows up (note to self: do NOT buy anything shipped via UPS only anymore!)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 20, 2014, 03:39:37 am
Damn, that looks nice! :-+

Honestly, I’ve always had a better experience with UPS. One time I had a 19” rack mount server shipped back to me from a data center. Where I lived at the time was in this little rural area off a suburb, we had a gravel driveway that came in from the main cul-de-sac and lead to a motorized gate. We had our zip code programmed as a valid code during certain hours of the day that all the delivery people knew about. I guess this guy was a temp or new or something, but he left this big ass package outside of the gate. In the pouring rain. I know they fucking carry large plastic bags in those trucks, he didn’t even wrap it. Anyway, FedEx paid me $2500, no questions after I showed them the pictures.

Personally, I think the biggest problem is packing. I posted a picture earlier in the thread of how my 2020B arrived. In a box about 1” larger than the unit itself. A smattering of bubble wrap and packing peanuts. I always instruct the sellers to wrap the item in 5+ layers of large bubble wrap in each direction and then (for bonus protection) line all four sides of the box with that stiff styrofoam board stuff. Ideally the item should snuggly fit inside the box with just the bubble wrap; if not add more bubble wrap until snug. Packing peanuts are a waste on large heavy items as they get crushed and the item settles to the bottom anyway. This way, if the item arrives broken and it wasn’t packed to my specifications, I basically get a refund either willingly or from eBay.

In other news, day 3 of the LT1001 burn-in on my 2020B continues. According to my 3456A, the unit has *drifted +0.001% in three days. Tonight I’m going to set it to 1V to collect more precise data, now that I know it’s stable.

*I’ve got the unit set to 20.000V and did a zero calibration to +0.000005 and a range calibration to +20.0000V three days ago. It’s been connected to the ‘56A the entire time with PLI at 100, Auto Zero and Auto Filter On and 6.5 Digits displayed. I’m running it in %Error mode [100(X-Y)/Y] on the front panel and collecting raw voltage data via GPIB on every trigger.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on November 20, 2014, 06:34:39 pm
That supply is coming to my office, so I'm not worried about the delivery per-se… it's more the brokerage fee(s) that I'm worried about. Which they don't need to tell you up front everything they could charge. Anyways, we will see.  It is stuck in customs at the moment, maybe 20mins from me. :(
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 24, 2014, 10:15:50 am
So, I got the 4010 pretty much cleaned up. I'm getting good at revamping front panels on these things now! =D

I took the switch assembly out (forgot to take detailed pictures of if, doh!) and cleaned it, put DeOXIT Shield on on the contacts and Lithium Grease on the bearings and such. Pulled the 10-turn rotary pot completely apart, cleaned it and applied DeOXIT Fader lube. I also scrubbed all the knobs, re-inked some of the faded numbering, disassembled, cleaned and greased the DigiPot control knob and replaced all the lamps.

Put it all back together and it's working better than before.

I've got to say, this thing is really stable, maybe more so than the 2020B.

I can literally dial in 1uV changes...and it's stable! I actually set it to 0.000001V, came back an hour later and hasn't drifted.

This thing was made in 1967. All discrete parts connected with point to point wiring on a turret board.  Think about that for a minute. How the hell do they get that kind of stability out of it?! (http://img.timb.us/emoticon/psyduck.gif)

Anyway, pictures!

(http://tapatalk.imageshack.com/v2/14/11/24/11903fa39d56e12253fa893f48d233c4.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/c21fc2f7bbdfa90296cfc924804b2e93.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/5bb7b3e7780ffdfe54578f0965c270e8.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/8c229fc2a45ce79bae561947b75ec2c5.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/ec766389636503d8f63984fd724eaa7f.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/63ac93873d375a25310432179d11496d.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/04d9d81e88515a8f00ae55e3273407e4.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/acf83cfb5f74d690a3e895633aa77d07.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/70daa852f84ed4e6cb27d15a293f39fe.jpg)

(http://tapatalk.imageshack.com/v2/14/11/24/f5d881e8413465f2a3cae6275ca88029.jpg)


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on November 24, 2014, 12:07:05 pm
Looking very good  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on November 24, 2014, 05:55:34 pm
YEs, nice indeed. What is that cylinder in the photo?

BTW - still no sign of the heater wire. I am beginning to wonder if you are just jerking me around on that, and haven't sent anything. A month is a long time...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on November 24, 2014, 08:12:22 pm
That's the 10-turn pot.

I dropped the package in the mail whenever I sent you the last PM. Along with some stuff for a friend and she hasn't gotten hers yet either. I think USPS is slow right now or something, maybe being the start of the Christmas season? It should be in this week I'd imagine. I've also got an incoming eBay package that's been last scanned at my local hub since Thursday, so maybe it's just my post office/hub bring horrible? :(


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Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on December 09, 2014, 12:44:37 am
Well this thread and others had me Jones'n for a PD 2005A for some time. Finally spotted THIS ONE (http://www.ebay.com/itm/201231324918?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT) for $72.   

With a bit of clean up it's looking nice. Pure beauty from a bygone era.

I have to say that I was pleasantly surprised by the size - smaller than I expected.  Out of the box it was within spec and easily even better with a quick and easy calibration.

No, I don't need this kind fo precision or stability for anything but damn it is nice to have.. does that make me a Volt Nut??? :-[

My vintage power supply habit is satiated again, at least for now.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: radhaz on December 09, 2014, 03:31:33 am
must...resist...urge...to...buy...

That sure looks nice! I've got one of their tracking supplies. New power device and it works perfect. Plus it's satisfying to look at the innards, seeing how stuff used to be built.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Sparky on March 06, 2015, 07:53:22 am
Hi folks! Since this thread has lots of Power Designs restoration info, I thought it appropriate to ask here about the control knobs used on many of the supplies.  I just picked up a Power Designs TP340A on eBay in excellent condition, though the voltage control knobs seem to have been replaced --- black plastic instead of the typical Aluminium.

The picture below shows the control knob of a TP340A identical to what is on my unit, compared to aluminum knobs on TP343A and TP325. 

I would like to restore the knobs on my unit to the classic aluminium version.  I've seen tons of "control knob" sellers on eBay, but wanted to check here if anyone knows a source for replacement knobs of the same Power Designs design?  (The shaft of the voltage control pots is 1/4" diameter.)

Thanks for any help!  I would love to see this unit looking classy again!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Sparky on March 09, 2015, 12:30:41 am
Hi folks! Since this thread has lots of Power Designs restoration info, I thought it appropriate to ask here about the control knobs used on many of the supplies.  I just picked up a Power Designs TP340A on eBay in excellent condition, though the voltage control knobs seem to have been replaced --- black plastic instead of the typical Aluminium.

The picture below shows the control knob of a TP340A identical to what is on my unit, compared to aluminum knobs on TP343A and TP325. 

I would like to restore the knobs on my unit to the classic aluminium version.  I've seen tons of "control knob" sellers on eBay, but wanted to check here if anyone knows a source for replacement knobs of the same Power Designs design?  (The shaft of the voltage control pots is 1/4" diameter.)

Thanks for any help!  I would love to see this unit looking classy again!

Anyone happen to have a TP343A or TP325 or model with similar size voltage control knobs?  If anyone could provide dimensions of the knob (width at base, width at finger grip part, overall height) that would be a big help to sourcing suitable replacements.  Thanks!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: radhaz on March 09, 2015, 03:16:18 am
There's a BIN Power Designs TP325 for $50 on ebay described as not working.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Sparky on March 10, 2015, 06:18:44 am
There's a BIN Power Designs TP325 for $50 on ebay described as not working.

Thanks for the heads up!  Salvaging from a broken unit is certainly one way to do it, though I hate to cannibalize something that doesn't look to be in too bad shape (plus the expense is much more than just the knobs).  Seems like I will eye-ball the dimensions based on photos and try to find a reasonable match in eBay.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: blueskull on March 10, 2015, 11:07:40 am
Uni trend is completely junk, and the link you gave is 404.

Almost all test equipment dealers (in China) tell me not to buy uni-t, even if they carry those.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on March 25, 2015, 03:52:36 pm
Hi, I just scored a Power Designs 4010 for a great price  :-+ It appears to have all it's original dust inside! I'm hoping that someone has a PDF of the manual or the schematic for this unit. I haven't been able to find one online yet. It would be much appreciated. So far, I've just done a quick voltage check. It works, but is not quite "spot-on" The 10-turn pot seems a bit squirrelly. Right now I'm doing a cosmetic clean up on the front panel and outside case. Thanks for anyone that can help.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: skyjumper on March 26, 2015, 04:40:08 am
Searching Ebay for one of these, I see that there are many "transistor" versions, which I assume are switching supplies. I realize switching supplies are going to be more noisy, but they are also smaller and lighter. I'm wondering, how much more noisy are they?

And I might grab one anyhow, since many of my projects are designed to be powered by a really dirty automobile power adapter.

Thanks!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on March 26, 2015, 04:45:14 am
Transistor just references it to being solid state(no vacum/electron tubes.)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on March 26, 2015, 04:54:38 am
Hi, I just scored a Power Designs 4010 for a great price  :-+ It appears to have all it's original dust inside! I'm hoping that someone has a PDF of the manual or the schematic for this unit. I haven't been able to find one online yet. It would be much appreciated. So far, I've just done a quick voltage check. It works, but is not quite "spot-on" The 10-turn pot seems a bit squirrelly. Right now I'm doing a cosmetic clean up on the front panel and outside case. Thanks for anyone that can help.

Very nice vindoline!

I don't know where to find a manual for the 4010 but the 2005A is probably similar enough that its manual which can be found HERE (http://exodus.poly.edu/~kurt/manuals/manuals/Other/POWER%20DESIGNS%202005A%20Technical%20Data.pdf) might be useful.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on March 26, 2015, 06:03:04 pm
Thanks mtdoc, I actually already have a 2005A and the manual thanks to Robrenz! I'm just uptight enough to want the "real" schematic before troubleshooting!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: skyjumper on March 27, 2015, 03:11:52 am
I just picked up this one for $67 delivered:

http://www.ebay.com/itm/290930177869 (http://www.ebay.com/itm/290930177869)

Other than the little dent in the upper right corner it looks pretty good and has a 14 day warranty. Should be fun to play with!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on March 27, 2015, 04:45:15 pm
Here's the status. On my initial check-out on receiving the 4010 I noted that the supply "worked" in as far as voltage appeared at the output. The output voltage did not track exactly with the setting and I noticed that the value would jump around as the setting dials were touched. OK, I expected the range switch assembly to need cleaning and lubrication. I also noted that the Oven light was unlit. I crossed my fingers hoping that the neon light was bad. Nope, the heater is open circuit  :--  I know there have been a few projects documented here about repairing or replacing these heated voltage references, I'll have to look into it further. Any advice is welcome! Also, I'm still looking for the schematic for this model. Thanks.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on March 30, 2015, 05:30:04 pm
I've got the Reference Amplifier Oven pulled from the 4010 now. Here are a couple of pictures with the cover and insulation removed. It's easy to see where the heater wire shorted and burned out  :--
The adhesive on the tape has completely failed and the insulation is pretty crusty. Does anyone know the specs of this wire? Is there a "best practice" or consensus on rebuilding these parts yet? Thanks.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on March 31, 2015, 09:54:33 am
There's a link for nichrome back a few pages in this thread IIRC (pg. 32?).

Just in case you're unable to rewind the nichrome wire & get it working however, perhaps A new, improved, oven for the PD 2005 Precision power supply (https://www.eevblog.com/forum/projects/a-new-improved-oven-for-the-pd-2005-precision-power-supply/) might be of interest.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on April 04, 2015, 05:57:39 am
Good evening, all.

Earlier today, I decided that rather than spending time and money putting cheap Chinese adjustable power modules in cases, I'd be better off just buying a triple output lab PSU and spending my time actually learning electronics and experimenting with circuits. It didn't quite go as planned though. You see, this afternoon, I won the auction on this Power Designs 5020 Precision Power Source (http://www.ebay.com/itm/DV68-Power-Design-Inc-Precision-Power-Source-Model-5020-/231517054298).

I know what you are thinking: That's not a triple output lab PSU! Clearly, something strange has happened, but what? I'm sure I'm not the first person who has had something like this happen! Can anyone help?

Or, perhaps more pragmatically, does anyone have any info that can help me track down a suitable replacement knob for the current control? As you can see from the photo in the listings, there is just a bare shaft.

I'm sure I'm going to have lots more questions once I actually have the unit in hand, and I still need a ready-to-use lab PSU, but that's a question for another thread.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on April 26, 2015, 07:50:22 am
My 5020 Precision Power Source arrived. Its in pretty good shape, except for a tiny bit of rust on some scratches on the case, and more than a little on the transformer core. There are also some signs of some corrosion on the front panel, I suspect it was stored near salt air at some point. Calibration is pretty good, though there is something out of wack on some of the positions on the 0-9v dial. I'm hoping that cleaning the contacts will take care of it. Load regulation seems pretty solid too across the voltage and current range.

I also found a TP340A for $99 that arrived today. Its in great shape, just a few scuffs on the outside. Rather than turn it on, I took it apart. Insides look great, very little dust. I noticed an obviously bad cap though, along with two identical ones that haven't failed yet.

Being that I'm a novice, and buying these to use in learning more about electronics, I could use some help picking and sourcing replacement caps. The caps in question are marked "Sprague, 5000, 100-25 DC, USA, 8405H." They are metal cans with a clear sleeve and a red cap with  axial leads.  I know from the users manual and googling that they are 100uF 25v polarized DC caps. I find plenty meeting that general description on digkey, etc, but don't really know what else to look for besides operating temp range and rated life, and I haven't been able to figure out those specs for the original parts.

Based on the date codes on the power transistors and some other components, this unit appears to have been built in the later half of 1996.

I also would appreciate advice on whether I should think of replacing the other electrolytic caps. There are 3 axial 10,000uF 25v Nichicon (with navy blue wrappers, if that encodes any info) and two axial 2200uF 60v with a -40-85°C range marked on the (lavender) wrapper without an obvious makers mark. There are also some capacitors marked "NASA, CE85°C" which according to the manual, are 330uF, 50v DC. None of these show obvious signs of failure.

So, I'd appreciate any guidance on picking and sourcing replacements for the failed cap, and also whether or not to replace the other caps.

Thanks.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on April 27, 2015, 05:51:29 pm
Hi

I recently bought a Hitachi V-1050F  (500 microvolts/div 100 MHZ) off of Ebay in the US.  The seller was selling it "as is" and the screen showed a faint light on it.  The controls did not look right (I am not an expert and it has been 45 years since I even touched a scope), so I asked if he would be willing to change the controls to what seemed better to me and he agreed.  He got two traces and revised the listing and put up new photos.  I knew I probably would have to pay more, and I paid $65 vs the starting price of $50.  But I felt better bidding on a working scope.  The seller had a HP 1200A ( 100 microvolts/ div  500k) and I could not resist it.  So now I am waiting to get 2 scopes.

SO  my question is --->

Is there a way a no experience seller could test one of these power supplies ( I just love the looks of these things) so I would know something about it.  Like for example, plug in and then see what lights should come on?  Could the seller short out the terminals with something like a knife (cannot assume they have bare wire) with the current set to min.  etc.

Here is what I guess -->

OFF  -- turn current limit to the left (I do not know how to use the other switch that is near by) -- set V to 20.00  -- nothing connected to terminals -- meter set to V  ---> turn ON   --  the meter should read 20  ??  Turn OFF

then if the above test passes do the following -->

set current limit all the way to the right (CW) -- set V to 00.00 --  meter to MA  -- short terminals with something (can a knife be used ?  I cannot assume everyone will have a bare wire) -- turn ON -- turn up  V very slowly ( how much would the dial have to move ?  would it get to 0.1 V ? )  See if the MA gets to max.   Would all 3 terminals need to be shorted?

What happens if V is increased too much ?  ie does a fuse blow or is there a protection circuit?

I know I will not learn about the pots

thanks for the advice and I am glad I found a really cool PS

Added -->  I forgot model numbers since there are many.  I like the ones with the cool voltage dials and vertical meter.  The only one I can find now on ebay is a 2020  (and $220).  It is turned on but the dials are set wrong.  It is set at 26 volts but reads 13 volts.   So lets start with the models with the cool dials like the 2020 (I do not know all the numbers yet).  I will also go for the ones with the horizontal meters and cool dials.

Update 4/27/2015  2:30 PM PST -->  found this 2010 on ebay (see pic)

on the dials is  " 26  40 "   I thought this was 26.40 v so I sent this msg to the seller:

"Do you have time to do a test on this? The controls in the picture are set wrong. It looks like it is set to 26.40 v but the max it puts out is 20v.

Can you set it to 16.40 volts? You would only have to move the left inner dial from 2 to 1

then tell me what the meter reads"

The seller sent me this:

"I quickly looked at this and if its a 20V max there would be dials going higher, so the switch on top is 0-10V and 10-20V, then the inner left dial is 0-9v and outer is 10th, so what your saying cannot be correct"

Since I do not have this (and cannot understand him), I guess I made a mistake.   What does it read?  How would you set the dials to 20v?

Also the threads on this subject are very long and I need to start over on them.  I have the manuals for the 2005 and 2020 but not the 2010.   I assume the manuals I have are good enough unless I do repair work (not skilled enough to do that)?  Tonight I will start reading about my love.

Falling in love with this PS is like falling in love with someone, common sense goes out the window.  Now to find the For Sale section of this forum and see if anyone has one of these for sale.


The price on ebay is buy it now at $199 + 9% tax  + 13.45 shipping    with Make Offer



thanks



Roger
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: helius on April 27, 2015, 06:03:06 pm
You don't say what kind of power supply it is. Lab power supplies (and any that I know of from Power Designs) can run forever into a dead short without damage. If the meters are working, they should show the current that is set on the current knob when shorted.

One thing to be aware of is the crowbar circuit (if the supply has one, they almost always require a screwdriver to turn). If the voltage exceeds the setting of the crowbar, it will cut the power until the unit is switched off or unplugged. The fuse is to protect the device in case of internal failure. In normal operation, it would not blow even if the output was set to max and shorted.

The third terminal (ground) is not needed for any functional test on a power supply. It is for referencing the output to mains earth only.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on May 10, 2015, 09:01:12 pm
I picked up a 2005A (not a 2020A, as I initially posted) from the mid 1970s on ebay. It arrived on friday. Before firing it up I took it apart so see if there were any obviously blown capacitors or anything. I didn't see any obvious problems, so I plugged it in and powered it up.

The oven control circuit seems to work. The light comes on and cycles, and the oven becomes warm to the touch.

Unfortunately, there is no output.

I'm not entirely surprised, since the the seller described it as powers on, unable to test, but pulled from a working environment. When I see that description from someone who deals in a lot of test equipment, I assume they are bending the truth, and that the probably doesn't work. In this case though, the seller seems to deal primarily in used office coffee equipment though, so I thought there would be some chance it worked and would just need some clean up.

Anyway, long story short, the seller has asked how I want to resolve this. As a starting point I was hoping others had thoughts on what seems a fair price for a 2020a in good physical shape but in need of repair.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on May 10, 2015, 09:19:45 pm
Hi eas, I don't know what you paid and I couldn't find any info for a 2020A. Is it a 2005A or a 2020B? Anyhow, it seems to me that the most problematic part in these supplies is the heated reference amp. Since you say this seems to be working I bet you can get the supply running. Mine have an internal fuse. Perhaps this is blown in your unit. In my opinion, anything under $100 is a real bargain for these units. In non-working condition I would take a chance at $50. Good luck!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on May 10, 2015, 09:31:33 pm
I had little brain fart. Its a 2005A (corrected my post).

I don't know if the reference amp itself is working, just that the oven control seems to be.

I figure I can get it working, but I paid what I paid assuming it already worked, even if it wasn't in spec.

Thanks for your take on $50 for a non-working unit. I think I paid about $85, shipped. I'm thinking A $30-40 refund would be fair.

It looks like some repairs were done in the distant past, and not necessarily all that well, since there are one or two partially lifted traces :(. That was a risk I took though.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on May 11, 2015, 01:20:38 am
"Do you have time to do a test on this? The controls in the picture are set wrong. It looks like it is set to 26.40 v but the max it puts out is 20v.

Can you set it to 16.40 volts? You would only have to move the left inner dial from 2 to 1

then tell me what the meter reads"

The seller sent me this:

"I quickly looked at this and if its a 20V max there would be dials going higher, so the switch on top is 0-10V and 10-20V, then the inner left dial is 0-9v and outer is 10th, so what your saying cannot be correct"

Since I do not have this (and cannot understand him), I guess I made a mistake.   What does it read?  How would you set the dials to 20v?

Roger

The PS is set for 12.640V just like the voltmeter reads.  The left most dial is 0-9 volts and the right most dial is 0-9 millivolts.
When you move the range switch to the 10-20V position you just add ten volts to the dial readings.The lower dial is for sub millivolt adjustments.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on May 11, 2015, 02:20:32 am
Quote
The PS is set for 12.640V just like the voltmeter reads.  The left most dial is 0-9 volts and the right most dial is 0-9 millivolts.
When you move the range switch to the 10-20V position you just add ten volts to the dial readings.The lower dial is for sub millivolt adjustments.

thanks I finally got it
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on May 11, 2015, 01:17:23 pm
2005a is an old, and simple design with a full schematic available making repair very viable.

http://www.rako.com/Articles/29.html (http://www.rako.com/Articles/29.html)

http://exodus.poly.edu/~kurt/manuals/manuals/Other/POWER%20DESIGNS%202005A%20Technical%20Data.pdf (http://exodus.poly.edu/~kurt/manuals/manuals/Other/POWER%20DESIGNS%202005A%20Technical%20Data.pdf)

If you have no output but the unit powers up insure the current limiting pot is OK as it tends to get squirrely with age.




Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on May 11, 2015, 04:25:45 pm
Check both fuses (there should be a fuse on the /inside/ of the case, right after the transformer on the secondary side). If there is a high draw (bad current limiting, higher than normal voltage, etc) this internal fuse can blow. I got two units (different models however) with this fault.  I am uncertain if the 2005 has this internal fuse.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on May 20, 2015, 06:30:22 pm
OK, As I posted above, I recently got a Power Designs 4010 for a great price, but the heater for the ovenized reference was burned out  :palm: My goal is to keep the repair as simple as possible and true to the original design. My initial plan was to find some suitable nichrome wire and rewind the heater. The original nichrome is insulated with something (fiberglass?) but I was unable to find any suitable replacement. I didn't want to worry about the bare nichrome shorting out. I also found that nichrome is a hassle to solder.

My solution was to use two 1"x3" adhesive backed, flexible kapton heating strips I found on eBay. I stripped off all the original nichrome wire and the plastic insulating material underneath until I was down to the bare metal can. The heaters were attached to opposite sides of the can, one near the top and one near the bottom, and wired in series. The heaters were then wrapped in a bit of extra Kapton tape to make sure they stayed put. I then insulated the heater with ordinary pink fiberglass insulation and secured that with more Kapton tape. Unfortunately, I neglected to take any photos before the oven was reassembled. The outer housing was replaced and the ovenized reference reinstalled in the power supply. A small notch was cut in the outer aluminum can to allow the heater wires to exit.

These heaters were rated for about 24-28V each, so with two in series I still needed to drop around 60 V. I used a 150 ohm 50W chassis mound resistor which works perfectly. It's mounted right to the side of the chassis with some thermal grease. It gets warm, but not hot to the touch. Unbelievably, there were two holes already in the chassis that fit the mounting tabs of the resistor perfectly! All I needed were a couple of self-tapping screws to affix the resistor.

During the repair process, I checked the large electrolytic caps. All of them checked fine for capacity and ESR. However the 680 uF across the supply output looked physically rather crusty, so it got replaced with a new 125C rated unit.

As a final modification, I wired the heater to power on only when the power supply was turned on. I've always felt that for my needs having the oven "always on" was wasteful as well as stressful on the heater and thermostat. The 4010 is again working great!  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on May 20, 2015, 06:35:28 pm
Sorry, I botched the attached images in the last post! Here they are.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on June 30, 2015, 02:48:43 am
Hi folks! Since this thread has lots of Power Designs restoration info, I thought it appropriate to ask here about the control knobs used on many of the supplies.  I just picked up a Power Designs TP340A on eBay in excellent condition, though the voltage control knobs seem to have been replaced --- black plastic instead of the typical Aluminium.

The picture below shows the control knob of a TP340A identical to what is on my unit, compared to aluminum knobs on TP343A and TP325. 

I would like to restore the knobs on my unit to the classic aluminium version.  I've seen tons of "control knob" sellers on eBay, but wanted to check here if anyone knows a source for replacement knobs of the same Power Designs design?  (The shaft of the voltage control pots is 1/4" diameter.)

Thanks for any help!  I would love to see this unit looking classy again!

I have a TP340A that also has black plastic knobs, as have a few others I've seen on ebay. As I recall, I also saw a scan of some old promotional materials for this model that had the plastic knobs. I think they are factory original, though perhaps not all TP340As shipped that way. The identifiable datecodes on  components in mine are circa 1996, which is quite late in the life of the company/brand. Perhaps it was a cost-cutting measure.

If so, it was like moving deck-chairs on the titanic. I think of how other stuff was manufactured in the mid-90s and compare it to this. The Keithley 2000 DMM I have, which I think was designed earlier in the decade, has two machine-poplulated PCBs with a ribbon cable between them. This thing has three hand-soldered PCBs and a serious wiring harness. That sort of hand-building might have been viable with the precision supplies, but this seems like more of a commodity. They may have been able to command a premium from individuals, but that would have been a small part of the market.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on June 30, 2015, 08:31:26 pm
Check both fuses (there should be a fuse on the /inside/ of the case, right after the transformer on the secondary side). If there is a high draw (bad current limiting, higher than normal voltage, etc) this internal fuse can blow. I got two units (different models however) with this fault.  I am uncertain if the 2005 has this internal fuse.

Thanks. I've checked both fuses. The internal fuse on the PCB was open, but replacing it didn't make an obvious difference. I need to give this unit a closer look, but I've been spending most of my repair energy on a TP340A that I'm trying to get back into spec (http://techobsessed.net/2015/06/power-designs-tp340a-repairrefurb/).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JoeB83 on July 07, 2015, 10:02:59 am
Hi all, I just acquired a PD 3650- 0-36V, 0-5A. Weighs about 35-40 lbs. I tried searching this thread for this particular model, but didn't find much.

This thing is a beast. So far, I love it, but I've only been using it for a couple weeks.

I'm curious, does anyone have a manual or just some general info on the PD 3650?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 07, 2015, 10:12:52 am
Hi all, I just acquired a PD 3650- 0-36V, 0-5A. Weighs about 35-40 lbs. I tried searching this thread for this particular model, but didn't find much.

This thing is a beast. So far, I love it, but I've only been using it for a couple weeks.

I'm curious, does anyone have a manual or just some general info on the PD 3650?
You'll find it in K04BB's Manuals Directory: 06 Misc Test Equipment/Power Designs page (http://ko4bb.com/manuals/index.php?dir=06_Misc_Test_Equipment/Power_Designs) (.pdf's available for the operator manual, schematic, and service manual).  :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JoeB83 on July 07, 2015, 07:52:35 pm
You'll find it in K04BB's Manuals Directory: 06 Misc Test Equipment/Power Designs page (http://ko4bb.com/manuals/index.php?dir=06_Misc_Test_Equipment/Power_Designs) (.pdf's available for the operator manual, schematic, and service manual).  :)

Thanks, I always seem to forget about that site!
I didn't realize it was so old-schematics are dated 1965! It's more stable than any other power supply of mine, I'm impressed.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Capt. Apparatus on September 05, 2015, 03:46:11 am
Just picked up a nice little Power Designs 4005 (a single not a twin) off eBay for like $14. The voltage while dead on won't go under 1v which I'm not sure was normal operation or a calibration issue. The pilot lamp is also burnt out, does anyone know the general specifications for the neon lamps used by Power Designs? Also I can't seem to find the service info anywhere not even on KO4BB's site so I really don't want to start playing with the trimpots just yet. ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on September 05, 2015, 05:08:07 am
Just picked up a nice little Power Designs 4005 (a single not a twin) off eBay for like $14. The voltage while dead on won't go under 1v which I'm not sure was normal operation or a calibration issue. The pilot lamp is also burnt out, does anyone know the general specifications for the neon lamps used by Power Designs? Also I can't seem to find the service info anywhere not even on KO4BB's site so I really don't want to start playing with the trimpots just yet. ;)

I doubt not going under 1v is normal.

The supply is probably pretty similar to the sources in a TW4005 of similar vintage. I've been hoarding every Power Designs PDF I come across, and unfortunately, I don't have a manual for the 4005 or the TW4005.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 05, 2015, 05:55:14 am
FYI guys, I've got PD2005 parts available if anyone needs them. A working reference board, pots, the switch array, transformer, freshly repainted cover, chassis, meter parts. Pretty much anything you'd need to fix a 2005. Send me a PM if you need anything! I've also got a 4010 Precision unit for sale in the Buy/Sell/Trade area that I've restored. (Very rare model. I've seen two on eBay in the last year, and that's one of them!)


Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on September 05, 2015, 11:42:00 am
Just picked up a nice little Power Designs 4005 (a single not a twin) off eBay for like $14. The voltage while dead on won't go under 1v which I'm not sure was normal operation or a calibration issue. The pilot lamp is also burnt out, does anyone know the general specifications for the neon lamps used by Power Designs? Also I can't seem to find the service info anywhere not even on KO4BB's site so I really don't want to start playing with the trimpots just yet. ;)

I have used these  (https://www.alliedelec.com/vcc-optoelectronics-2ml/70152563/)successfully.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on September 05, 2015, 01:32:50 pm
FYI guys, I've got PD2005 parts available if anyone needs them. A working reference board, pots, the switch array, transformer, freshly repainted cover, chassis, meter parts. Pretty much anything you'd need to fix a 2005. Send me a PM if you need anything!

What's missing from the 2005 to prevent you from restoring the one you have?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 05, 2015, 05:57:43 pm
Hi

I have a TP340 and everything works (all ranges will go to the max volts and amps).  Except the bottom meter.  On volts it works on amps it does not.  I can use a multimeter to monitor the amps if needed but I wonder if this would be an easy fix or maybe not worth the effort?

thanks
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 05, 2015, 08:13:40 pm

FYI guys, I've got PD2005 parts available if anyone needs them. A working reference board, pots, the switch array, transformer, freshly repainted cover, chassis, meter parts. Pretty much anything you'd need to fix a 2005. Send me a PM if you need anything!

What's missing from the 2005 to prevent you from restoring the one you have?

The meter, oven and rectifier board. I've got the parts to build a replacement rectifier board, but I'd need a base/socket assembly for the oven (this one is completely crumbled). The unit is completely in pieces too, which is the main reason I thought I'd keep it for parts.

I've also got a 2005A that's in immaculate shape, aside from a missing oven assembly/reference board.


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MaxFrister on September 06, 2015, 02:52:15 pm
Of course it is worth fixing!  This is a great power supply.

I may be very simple.  I bought a 340 that had probably been bumped on face and breaking the lowest V/A switch.  I opened it up to replace it and found all of the switch pieces parts although some of the plastic was broken.  With a little tiny cable tie, I put the switch back together and it all works now.

Max


Hi

I have a TP340 and everything works (all ranges will go to the max volts and amps).  Except the bottom meter.  On volts it works on amps it does not.  I can use a multimeter to monitor the amps if needed but I wonder if this would be an easy fix or maybe not worth the effort?

thanks
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Capt. Apparatus on September 07, 2015, 02:40:59 am
I doubt not going under 1v is normal.

The supply is probably pretty similar to the sources in a TW4005 of similar vintage. I've been hoarding every Power Designs PDF I come across, and unfortunately, I don't have a manual for the 4005 or the TW4005.


By going through the manuals from a few similar models and using a little common sense I've been able to mostly suss out what the three trim pots do. Meter seems to track dead on now still out of spec on the low end though as far as minimum values go. minimums should be 0v and 25ma, however mine settle at 1 volt and 23ma. I'm sure more than a couple of components drifted off spec but for now I'll leave it as is until I can muster the energy to go through the whole unit.


I have used these  (https://www.alliedelec.com/vcc-optoelectronics-2ml/70152563/)successfully.

Thanks for the heads up on the lamps, I've got a few extra neons from a tektronix refurb I did a few years back kicking around here somewhere. Can't remember if they're 60 or 90 volts though, I'll probably give them a try though. I also hope the what I assume is a lamp holder isn't too much of a pain in the behind to open up.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on September 13, 2015, 04:21:28 pm
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 13, 2015, 07:21:27 pm
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.

I am the high bidder

I assume this model does not have an oven - since there is no oven light

I will probably ask the seller to turn it on and tell me what happens.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on September 13, 2015, 08:18:04 pm
Manual says no oven. Doesnt specify the v-ref.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 13, 2015, 09:56:57 pm
I thought the v-ref in the non-oven models was an LM399 with different tolerances. Ah, here's the thread about it:

https://www.eevblog.com/forum/projects/pd-2020b-question/ (https://www.eevblog.com/forum/projects/pd-2020b-question/)

And schematics (it's U3):

http://exodus.poly.edu/~kurt/manuals/manuals/Other/POWER%20DESIGNS%202020B,%205020,%20C500%20Instruction.pdf (http://exodus.poly.edu/~kurt/manuals/manuals/Other/POWER%20DESIGNS%202020B,%205020,%20C500%20Instruction.pdf)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 13, 2015, 10:26:03 pm
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.

Any suggested max bids?  I am currently at $177 but I have missed several over the last year so I am thinking of going to $233.  I am in love with these power supplies.

Anyone want to sell theirs?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on September 13, 2015, 11:35:33 pm
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.

Any suggested max bids?  I am currently at $177 but I have missed several over the last year so I am thinking of going to $233.  I am in love with these power supplies.

Anyone want to sell theirs?

Ahh, so you are the one! I was the original bidder. I already have a few PD precision supplies of different vintages & specs, including another 5020. The 5020s seem pretty rare, so I thought I'd bid. I'd already decided not to get into a bidding war on it though. 

You are already past what I'd be willing to spend. If you like the look and the precision, you could probably get a lower-specced supply for closer to $100. I got both of my 2005a's for ~$60 shipped. Neither of them were working, but one just needed a new fuse and power cord. The other probably doesn't need much either, but I haven't spent the time to finish troubleshooting it yet.

If you like the precision and the volt/current range, you should be able to pick up an HP6114 on an auction or best-offer. The 6114 doesn't have the nice brushed aluminum aesthetic, but I still find the industrial design pleasing and evocative.

I'll also say that from a human-factors perspective, the dials on the PD precision supplies have a shortcoming, in that the meaning of the inner vs outer knob isn't consistent -- of the two digits handled by the right-hand controls knob sets the least significant digit, while the knob sets the most-significant digit of the two digits handled by the left-hand controls. Yes, there is a logic, but the fact that there are alternative mental models puts an added cognitive burden on the user, which can lead to mistakes. I think the HP 6114's dial controls have less ambiguity.

A few things I've noticed about the 5020 in that listing:

As for the Vref, definitely not one of their custom ovenized references. Probably an LM399
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 14, 2015, 01:09:45 am
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.

Any suggested max bids?  I am currently at $177 but I have missed several over the last year so I am thinking of going to $233.  I am in love with these power supplies.

Anyone want to sell theirs?

I've got a restored 2020B I could sell you for $250, shipped. It uses an LM399 ovenized vref.

I replaced all the power and signal transistors with modern versions (the power transistors were changed from MS1700's to 2N3773's with 1996 date codes since the originals were unobtainable anymore; signal transistors were replaced with current production versions of the original part number).

Replaced both op-amps with modern versions (the original voltage regulation op-amp was an OP-05 which I changed to a more stable and precise LT1001; the current regulation op-amp was an LM358, which I replaced with a current production version of).

Replaced every electrolyte on the unit and put in a brand new (old stock) meter. I also repainted the case and cleaned, lubed and applied DeoxIT to the switches.

It should last another 30 years now.

It's ultra, ultra stable. You can dial in 1uV changes and it'll stay there.

Edit: Added part numbers.


Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: The Doktor on September 14, 2015, 01:47:25 am
I just received a 4010 restored by timb. It's exactly what he said it was, in case you're considering his offer.

Ed
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 14, 2015, 01:55:10 am

I just received a 4010 restored by timb. It's exactly what he said it was, in case you're considering his offer.

Ed

I hope you're happy with the unit! It's a very nice little box. :)


Sent from my Smartphone
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 14, 2015, 01:58:19 am
I just received a 4010 restored by timb. It's exactly what he said it was, in case you're considering his offer.

Ed

Yes I did.  I missed the 4010 and was pissed  :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: uoficowboy on September 14, 2015, 02:10:48 am
For anybody interested in a PD precision supply - there's a 5020 on Ebay here: http://www.ebay.com/itm/252087857361 (http://www.ebay.com/itm/252087857361) (I have no connection to this auction, BTW)

5020s are pretty rare. I'm quite a fan of mine.

Any suggested max bids?  I am currently at $177 but I have missed several over the last year so I am thinking of going to $233.  I am in love with these power supplies.

Anyone want to sell theirs?

Ahh, so you are the one! I was the original bidder. I already have a few PD precision supplies of different vintages & specs, including another 5020. The 5020s seem pretty rare, so I thought I'd bid. I'd already decided not to get into a bidding war on it though. 

You are already past what I'd be willing to spend. If you like the look and the precision, you could probably get a lower-specced supply for closer to $100. I got both of my 2005a's for ~$60 shipped. Neither of them were working, but one just needed a new fuse and power cord. The other probably doesn't need much either, but I haven't spent the time to finish troubleshooting it yet.

If you like the precision and the volt/current range, you should be able to pick up an HP6114 on an auction or best-offer. The 6114 doesn't have the nice brushed aluminum aesthetic, but I still find the industrial design pleasing and evocative.

I'll also say that from a human-factors perspective, the dials on the PD precision supplies have a shortcoming, in that the meaning of the inner vs outer knob isn't consistent -- of the two digits handled by the right-hand controls knob sets the least significant digit, while the knob sets the most-significant digit of the two digits handled by the left-hand controls. Yes, there is a logic, but the fact that there are alternative mental models puts an added cognitive burden on the user, which can lead to mistakes. I think the HP 6114's dial controls have less ambiguity.

A few things I've noticed about the 5020 in that listing:
  • The top-case isn't as perforated as my 5020, 4010 and 2005a.
  • The current and vernier settings knobs are unusual. First, they match, which is odd because most of the 5020 4020 and 4010 supplies I've seen have a 10-turn counting knob for the vernier. Second, they don't look like the knobs used on most PD supplies. They might be replacements, but I've seen similar knobs on one triple output supply. It might be that they are factory original, some of their other later supplies also have different knobs (Bitseeker and I both have TP340a supplies with similar black resin knobs.
  • The markings on the precision dials are a plastic appliqué, not the engraved and painted markings seen on most PD precision supplies. My PD5020 is a hybrid. It has engraved markings on the right-hand controls, and plastic applique on the left.
  • The meter needle is black, rather than the high-visibility color pink used on most of my PD supplies, including others with that same style of meter. My TP340a, from the mid-1990s, has that same style meter too, but also has black needles on the meters, along with newer, less awesome knobs. It's still a nice, solid supply though.

As for the Vref, definitely not one of their custom ovenized references. Probably an LM399
I noticed that it's different from my 5020 as well - the things that stood out were the different meter and the lack of a counting dial on the mv knob.

As for if it has an oven - no. I believe it uses a very similar circuit to that of the 2020.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 14, 2015, 10:28:49 am
The meter may be a replacement. The standard edgewise meter used in these supplies is a GE Type 185 with 1mA movement. You can find them on eBay as new old stock. (If you buy one, make sure it's 0-1mA as they also made 500-0-500uA versions with the needle in the center of the scale instead of at the bottom. The one you want will say "RTG 1MA" on the label of the meter.)

Just pop the scale out of your old meter and pop it in the new one.

(Also, ask the seller for a picture of the meter in question if he just has a shot of the box; they made needles in white, black and orange.)


Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: The Doktor on September 16, 2015, 03:13:09 am

I just received a 4010 restored by timb. It's exactly what he said it was, in case you're considering his offer.

Ed

I hope you're happy with the unit! It's a very nice little box. :)


Sent from my Smartphone


Yes, I am quite satisfied with it. I was pleasantly surprised when I took it out of the box, I was kind of expecting the packaging material to be stuck to the fresh paint. Based on my experience with other peoples repaints, I was seriously hesitant to purchase the supply at all. I have seen a lot of repainted equipment at hamfests, the paint is usually sticky or at least so soft you can leave fingerprints in. Your paint job was very nicely done, you would be doing many people hear a favor if you explain your technique and what materials you use.

As for function, I was expecting it to work perfectly, and it does. Can't really say too much more than that. I turned on the supply and my HP 34401a and let them warm-up for a few hours, then I sent the supply to 5.00V and noted that it was less than 150 µV low. I set the meter to min/max mode and have monitored it at this setting for 24 hours three times, each time the total variation over that period is less than 200 µV, I did not record the actual numbers each time, but I believe it was probably actually within that tolerance over the entire three days. The meter and power supply were both close to a wall, and most of the voltage variation occurred the first time the central air cycled on and off. Not bad at all for a 40-year-old power supply.

This little supply should have a long and happy life with me, it will only be getting used where I want a very stable and accurate voltage source, such as when I am playing with high-resolution analog sensors. It will be a rare occasion when it needs to supply more than a few tens of milliamps. Its first use will come sometime over this winter, when I attempt to repair/restore a Fluke 301E power supply which I purchased about 25 years ago at a farm auction, I believe for the princely sum of $5 :-) it is also a high precision power supply, but a pure tube design looking like it was built sometime in the 50s or 60s. It is a rather impressive beast, delivering 1.02-512V at 300ma, and claiming .1% accuracy. The 4010 will be standing in for an Eppley miniature standard cell until I am sure the Fluke is in good enough condition to be worth repairing, then I will need to design a permanent replacement for the standard cell.

Now if I could only find a PD 6150 that was not rackmount...


Ed
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 16, 2015, 03:25:54 am
Quote
(Also, ask the seller for a picture of the meter in question if he just has a shot of the box; they made needles in white, black and orange.)

I do not understand what you mean.

Just in case here is the listing:

http://www.ebay.com/itm/252087857361?_trksid=p2055359.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/252087857361?_trksid=p2055359.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Someone talked about how confusing the dials can be.  I missed a unit one time because I could not understand how they worked and the seller did not know either.

What ever short comings this has does not matter to me.  This thing is just too sexy.
I'll probably put it on the fireplace mantle.  It would make me feel like I am living in the Outer Limits.  :-+


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: The Doktor on September 16, 2015, 04:04:24 am
Quote
(Also, ask the seller for a picture of the meter in question if he just has a shot of the box; they made needles in white, black and orange.)

I do not understand what you mean.

Just in case here is the listing:

http://www.ebay.com/itm/252087857361?_trksid=p2055359.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/252087857361?_trksid=p2055359.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Someone talked about how confusing the dials can be.  I missed a unit one time because I could not understand how they worked and the seller did not know either.

What ever short comings this has does not matter to me.  This thing is just too sexy.
I'll probably put it on the fireplace mantle.  It would make me feel like I am living in the Outer Limits.  :-+

The dials are not confusing at all, each dial sets one digit in the output voltage. It is just like entering it on a keyboard, except you do it with four dials. The numbers are read from left to right, just like any other number. In the listing you referred to, it is set to 03.30V, note how those numbers show up in the little "window" in the piece of plastic.

The little knob below the center of this window is a fine voltage adjustment, it adds anywhere from 0 to 10 mV to the output voltage.

The little knob to the left of that, marked "Current Limit"sets the maximum current the supply will deliver. If you turn this all the way to the right, current limit will occur at the supplies maximum rating, you cannot damage these applied by turning it up too high. As you turn to the left, the supply will begin current limiting at the lower level, operating in constant current mode. IOW, it will raise or lower the output voltage until the current is at the set level, but under no circumstance will it exceed the voltage set by the knobs above.

Besides the constant current feature being useful in some situations, you should understand that the supply is designed in such a way that it can be connected to a short-circuit indefinitely without being damaged.

And yes, it is a very sweet looking supply. If you need something with a bit more power, consider a 6050 or a 6150.


Happy shopping  :)
Ed
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 16, 2015, 04:14:43 am
Quote
(Also, ask the seller for a picture of the meter in question if he just has a shot of the box; they made needles in white, black and orange.)

I do not understand what you mean.

He's referring to the color of the needle in the volt/amp meter. Notice how the needle is black on that 5020, as compared to the orange/red one on this 2005:

http://www.ebay.com/itm/Power-Designs-MODEL-2005-Precision-Power-Supply-LOC1112-/291535984529 (http://www.ebay.com/itm/Power-Designs-MODEL-2005-Precision-Power-Supply-LOC1112-/291535984529)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 16, 2015, 04:20:24 am
The dials are not confusing at all, each dial sets one digit in the output voltage. It is just like entering it on a keyboard, except you do it with four dials. The numbers are read from left to right, just like any other number. In the listing you referred to, it is set to 03.30V, note how those numbers show up in the little "window" in the piece of plastic.

The part that might cause some confusion after acclimating to the general operation of the dials is the rightmost value, since it goes from 0-(10) instead of 0-9. Since the maximum value that could be reached under normal circumstances would be 49.99, that last digit goes to 10, instead of 9.

49.9(10) = 49.99 + 0.01 = 50.00
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 16, 2015, 04:47:37 am
The dials are not confusing at all, each dial sets one digit in the output voltage. It is just like entering it on a keyboard, except you do it with four dials. The numbers are read from left to right, just like any other number. In the listing you referred to, it is set to 03.30V, note how those numbers show up in the little "window" in the piece of plastic.

The part that might cause some confusion after acclimating to the general operation of the dials is the rightmost value, since it goes from 0-(10) instead of 0-9. Since the maximum value that could be reached under normal circumstances would be 49.99, that last digit goes to 10, instead of 9.

49.9(10) = 49.99 + 0.01 = 50.00

This is what happened to me  - thanks
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 16, 2015, 05:03:08 am
The part that might cause some confusion after acclimating to the general operation of the dials is the rightmost value, since it goes from 0-(10) instead of 0-9. Since the maximum value that could be reached under normal circumstances would be 49.99, that last digit goes to 10, instead of 9.

49.9(10) = 49.99 + 0.01 = 50.00

This is what happened to me  - thanks

Glad that helped. It may seem weird to do it that way, but if PD made the leftmost digit go to 5 instead of 4, then people might expect the supply to go up to 59.99, which it can't since it's a 50V supply.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 16, 2015, 07:17:24 am


I just received a 4010 restored by timb. It's exactly what he said it was, in case you're considering his offer.

Ed

I hope you're happy with the unit! It's a very nice little box. :)


Sent from my Smartphone


Yes, I am quite satisfied with it. I was pleasantly surprised when I took it out of the box, I was kind of expecting the packaging material to be stuck to the fresh paint. Based on my experience with other peoples repaints, I was seriously hesitant to purchase the supply at all. I have seen a lot of repainted equipment at hamfests, the paint is usually sticky or at least so soft you can leave fingerprints in. Your paint job was very nicely done, you would be doing many people hear a favor if you explain your technique and what materials you use.

As for function, I was expecting it to work perfectly, and it does. Can't really say too much more than that. I turned on the supply and my HP 34401a and let them warm-up for a few hours, then I sent the supply to 5.00V and noted that it was less than 150 µV low. I set the meter to min/max mode and have monitored it at this setting for 24 hours three times, each time the total variation over that period is less than 200 µV, I did not record the actual numbers each time, but I believe it was probably actually within that tolerance over the entire three days. The meter and power supply were both close to a wall, and most of the voltage variation occurred the first time the central air cycled on and off. Not bad at all for a 40-year-old power supply.

Wow, I really appreciate the compliment! These are the first ones I've sold, so it's really, I dunno, validating. :D

My cousin is a professional  auto-body painter and taught me a good deal last year. These cases were originally done in some type of heavy duty enamel with a textured impression. To preserve that texture, I use ultra fine grit sanding blocks to *evenly* remove a thin layer of the existing paint. Then I use Rustoleum (Lagoon Blue is the best off the shelf match, it's a bit more blue than the original blue-green) and apply it from about 24" away. The trick is to just "mist" the paint on in broad, even strokes.

I do at least 3 coats like that, letting each dry under a heat lamp for 24 hours (don't place the heat lamp too close or the paint will bubble up; I keep my lamp about 5' above the counter). After the last coat I do a single coat on the inside and let it dry naturally for 48-hours. Finally, I use a clear matte enamel overcoat for extra scuff protection and solvent resistance. (Though, your case was one of the first ones I did, and I think I used a Krylon brand clear overcoat; I'm not sure if it's enamel or not.)

Finally, I leave it under a heat lamp for about a week to fully cure.

Patience is the biggest key to painting. That and preparation.

If anyone is interested, I can do a short video showing the spray technique and the ins and outs of various off the shelf paints. Plus how to prepare the surface, etc.




Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 16, 2015, 07:47:25 am
If anyone is interested, I can do a short video showing the spray technique and the ins and outs of various off the shelf paints. Plus how to prepare the surface, etc.

+1 for timb vintage equipment restoration videos (cleaning, painting, and more)!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: robrenz on September 16, 2015, 11:07:24 am
+2  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 16, 2015, 04:10:35 pm
+3  :-+   Maybe on the next one I get
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on September 16, 2015, 05:50:46 pm
+4  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on September 17, 2015, 01:03:18 am
The dials are not confusing at all, each dial sets one digit in the output voltage. It is just like entering it on a keyboard, except you do it with four dials. The numbers are read from left to right, just like any other number. In the listing you referred to, it is set to 03.30V, note how those numbers show up in the little "window" in the piece of plastic.

The part that might cause some confusion after acclimating to the general operation of the dials is the rightmost value, since it goes from 0-(10) instead of 0-9. Since the maximum value that could be reached under normal circumstances would be 49.99, that last digit goes to 10, instead of 9.

49.9(10) = 49.99 + 0.01 = 50.00

I'm the one who noted the potential for confusion. The issue I had in mind isn't that you need to turn the least significant digit up to 11 10 to get the full voltage range, nor is it a problem figuring out how to read the dials (though some people seem to have had that problem). The problem is in setting them.

The meaning of the inner knob and outer ring isn't consistent between the left and righthand controls. On the right, the inner knob sets the least significant digit. On the left, the inner knob sets the most significant digit. This is unlikely to be a problem when you set and forget. It could be a problem when incrementing through a range of voltages, perhaps while focusing on something else, like the response of a meter and you jump from 0.99v to 10.99v while intending to go to 1.99v. This confusion is much less likely with the dials on an HP precision supply, or the non-concentric decade knobs any number of devices, like a GenRad decade box.

Some people may never have a problem with it. Others will only have a problem now that I've pointed it out. I discovered the problem on my own, and because I care about human factors, considered whether there was something about the device that tripped me up. It isn't enough reason for me to sell off my PD precision supplies -- I only mentioned it because it might give ez24 a pretense for not kicking himself if he misses out on winning this auction.

Another +1 on a painting tutorial video. The paint on my PD 5020 is compromised by rust. I've cleaned it and oiled it, but its really going to need more than that.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on September 17, 2015, 10:41:15 pm
The first step is admitting you have a problem...

We're going to have house guests in a few days, so I've been moving stuff down to basement storage so I can convert my "lab" back to a dining room. I was  struck by how many PD supplies I've accumulated looking for deals on eBay over the past six months.

(https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=171574;image)

All but one of the precision supplies are nominally operational. The 5020 (lower left), and 2020a (top center) needed cleaning and adjustment. One of the 2005a (both 2005a are stacked in the lower right) needed a new cord and fuse, cleaning and adjustment. It is nominally functional, but may need more troubleshooting and repair to get stability and ripple in spec. The 2020 is functional but settings are out of wack after cleaning and adjustment. I want to replace caps and revise some earlier repairs and perhaps trim some of the resistors in the decade divider. The TP340a needed a lot of troubleshooting (described elsewhere in this forum and on my blog). It is now functional and stable, but I've seen some evidence that the crowbar on Source B may need attention. The 6010 (top right) needed a new fuse and pot, its now somewhat functional, but voltage tops out at 15v. I suspect something in the "uniply" solid-state tap-switching or one of the output transistors and need to do more troubleshooting and repair. I've spent some time on the non-functional 2005a and need to spend more, because it powers on, the oven cycles, but there is no output.

Once I've got them all tuned up, I'll probably keep the TP340a 5020, 2020a and the 2020 and sell the 6010 and one or both of the 2005a.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 18, 2015, 12:40:51 am
That's quite a collection, eas. Thanks to you, so far I've been able to hold steady at one TP340A. But those precision versions sure are purdy. :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 18, 2015, 02:19:27 am
Quote
The first step is admitting you have a problem...

Glad to know I am not the only one.  PM when you start selling the 2005s
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 18, 2015, 06:28:33 am
ez,

Looks like you got a good deal on the 5020. Looking forward to hearing all about it when it arrives.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on September 18, 2015, 03:15:10 pm
@ eas, impressive  :clap:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 18, 2015, 05:55:14 pm
ez,

Looks like you got a good deal on the 5020. Looking forward to hearing all about it when it arrives.
Thanks will do
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on September 19, 2015, 07:24:44 am
The first step is admitting you have a problem...

You're a sick man eas! and I mean that in a good way...

I've only got 2 PD supplies.  So far.. ::)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: fcb on September 19, 2015, 07:56:05 am
I've hankered after one of these units for quite awhile now - I absolutely love US gear of that era.

Has anyone got a link that details the history & what happened to Power Designs Inc???
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 19, 2015, 08:22:09 am
Has anyone got a link that details the history & what happened to Power Designs Inc???

A few months ago, I tried to find some info on PD, but their name is rather generic, which yielded a lot of irrelevant search results. I'd like to know more about their history too.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SeanB on September 19, 2015, 01:04:33 pm
Try Ambitrol, they seem to have taken over the PD business. I was bidding for one, but it went for $1.25 with $30 shipping.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on September 19, 2015, 07:16:40 pm
Try Ambitrol, they seem to have taken over the PD business. I was bidding for one, but it went for $1.25 with $30 shipping.
Ambitrol seems to have been one of their trademarks, along with UNIPLY, REDULE, and PD (source (http://www.trademarkia.com/company-power-designs-inc-972591-page-1-2)). PD trademark expired in 2008, and on a previous search, there hasn't been any activity with the corporation (filing) since 1991.

Precious little information it seems (there is a NY Times article regarding share reacquisition, but it doesn't give a year; here (http://query.nytimes.com/gst/abstract.html?res=9F04EFD6173BE033A2575BC0A9639C946391D6CF)).
Title: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 19, 2015, 09:37:47 pm
They also had several locations in NY during their history, plus they had a west coast division in California that made high voltage supplies and dividers.

Last year I spent weeks trying to find information on the company, I posted what I found somewhere in this thread, but it's not much. They seem to have gotten acquired and vanished into thin air.

They made some versions of the 2020B and 5020A that were in plastic cases, with fans and used those push button plastic digit switches. Nearest I can tell, these were made post-acquisition, built to a cost and basically junk, despite using the same basic circuit and being part of the precision line. This would be circa the early 90's. Avoid these if you see them on eBay.

You know, I even spent time going through issues of Pop Elec from the 60's and Byte from the 70's, looking for ads. Never found anything. (Though I did find an ad for Lambda supplies in Byte.)

You know, the 2020B, 5020A and C500 designs are all pretty damn good and could easily be modernized. Just replace the switch array with a precision DAC, which would increase the stability since you wouldn't have to worry about the resistors on the switch array drifting. The rest of the circuit would be the same, just with modern transistors, op-amps and the same ovenized LM399. I've actually thought about doing it, but I'm not sure how much of a market there is for an affordable lab grade precision supply.


Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 19, 2015, 10:19:22 pm
Quote
They seem to have gotten acquired and vanished into thin air.

Maybe they came from the same place as Mat Franco.  Aliens do not have to be extreme and go around blowing up the world.  I believe Mat Franco is an alien with supernatural powers.  What better way to live among earthlings than act like a magician?  Why would a large company just disappear?  It would be interesting to find out if Mat worked for Power Designs, he could make them disappear.

So for those that work on these things, keep your eye open for unusual tool marks or components or construction methods.  Can you imagine how valuable these will be if we can prove they were made by aliens?

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on September 19, 2015, 10:33:28 pm

Quote
They seem to have gotten acquired and vanished into thin air.

Maybe they came from the same place as Mat Franco.  Aliens do not have to be extreme and go around blowing up the world.  I believe Mat Franco is an alien with supernatural powers.  What better way to live among earthlings than act like a magician?  Why would a large company just disappear?  It would be interesting to find out if Mat worked for Power Designs, he could make them disappear.

So for those that work on these things, keep your eye open for unusual tool marks or components or construction methods.  Can you imagine how valuable these will be if we can prove they were made by aliens?

At least they weren't made by David Copperfield. I don't want my power supply to assault and rape me, then offer me large amounts of money to keep quiet.

(Also, Penn Jillette is totally the best magician ever. The bullet trick will confound me until the day I die.)


Sent from my Tablet
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on September 21, 2015, 12:35:41 am
I pulled some information from archived versions of the Powerdesigns web site a while ago. I compiled it into a Power Designs Inc. timeline (http://techobsessed.net/power-designs/) and posted it on my site. Right now its more about the death-throws. I'd like to fill in more information from their glory days.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 21, 2015, 01:43:22 am
If enough info can be cobbled together, especially if it includes online references, a Wikipedia page could be started on it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on September 21, 2015, 03:04:20 am
If enough info can be cobbled together, especially if it includes online references, a Wikipedia page could be started on it.
I do not thing aliens will allow this.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on September 21, 2015, 04:04:58 am
I do not thing aliens will allow this.

Shhh! If they know that you know, it could mean big trouble for us Earthlings. :-X
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: fcb on September 22, 2015, 04:58:31 pm
If enough info can be cobbled together, especially if it includes online references, a Wikipedia page could be started on it.
Do it!!!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 02, 2015, 07:36:26 pm
A Power Designs 2020b Precision DC Power Source (http://www.ebay.com/itm/Power-Designs-Model-2020B-Precision-DC-Source-Tested-Free-Shipping-/181891221870) just showed up on eBay for $129.99 or best offer + shipping. It looks to be of similar vintage to the 5020 that ez24 bought a few weeks ago. It has the same housing, knobs, and decals markings on the decade dials.

The serial number starts with 92, which I think means it was made in 1992, a convention I think they adopted around 1990, based on a comparison of serial numbers and component date codes on a few of my supplies.

Last week, I was tweaking my power designs eBay searches, and in the process, I found a poorly listed "6005" supply. I've never seen this model before, and the price was good, so I bought it. After waiting for the better part of a week to get a tracking number, I started looking more closely at the seller, and found they also had a 60's or early-70's era 2020 Precision DC Power Source, also at a good price, so I bought it. Both are on their way, should be here next week. I'll post photos when they arrive.

Which reminds me, ez24, you must have your 5020 by now. How is it? Any photos of the internals so we can do some comparative anatomy?  Also, bitseeker, how's your TP340a comping?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 03, 2015, 03:03:48 am
A Power Designs 2020b Precision DC Power Source (http://www.ebay.com/itm/Power-Designs-Model-2020B-Precision-DC-Source-Tested-Free-Shipping-/181891221870) just showed up on eBay for $129.99 or best offer + shipping.

That's a nice one, alright.

Quote
Last week, I was tweaking my power designs eBay searches, and in the process, I found a poorly listed "6005" supply. I've never seen this model before, and the price was good, so I bought it. After waiting for the better part of a week to get a tracking number, I started looking more closely at the seller, and found they also had a 60's or early-70's era 2020 Precision DC Power Source, also at a good price, so I bought it. Both are on their way, should be here next week. I'll post photos when they arrive.

Wow! Looking forward to seeing those.

Quote
Also, bitseeker, how's your TP340a coming?

It's coming along quite well, I'm happy to say. I started a post on it with some pics and notes. https://www.eevblog.com/forum/repair/power-designs-tp340a-repair-and-facelift/ (https://www.eevblog.com/forum/repair/power-designs-tp340a-repair-and-facelift/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on October 03, 2015, 05:45:42 am
Quote
Which reminds me, ez24, you must have your 5020 by now.

Yes among other ones.  I will fire it up tomorrow.  Do you want me to take pics of the inside?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 03, 2015, 06:38:33 am
I'll definitely get pix up of both 2020 supplies, once I get the second one. I think they are my favorite power designs supplies. I like the rounded square GE meters, and I like the symmetry of the vertical orientation. The handle in the depression on top is nice too.

Quote
Which reminds me, ez24, you must have your 5020 by now.

Yes among other ones.  I will fire it up tomorrow.  Do you want me to take pics of the inside?
Of course!!! Don't turn it on, take it apart!



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on October 04, 2015, 03:15:29 am
I'll definitely get pix up of both 2020 supplies, once I get the second one. I think they are my favorite power designs supplies. I like the rounded square GE meters, and I like the symmetry of the vertical orientation. The handle in the depression on top is nice too.

Quote
Which reminds me, ez24, you must have your 5020 by now.

Yes among other ones.  I will fire it up tomorrow.  Do you want me to take pics of the inside?
Of course!!! Don't turn it on, take it apart!

How funny. 
I ran it (5020) through its paces in 10 volt steps at min and max amps.  I have a Uni-T 139C that I used for voltages.  The range of the last digit .0x  ranged from 0 to 2 different than my meter, mostly on the high side.  Example:  set at 30.00 volts, Uni said said 30.01
The meter works both in volts and amps

It is really cool to be able to dial in the volts, first instrument that I have that does this.

Bad thing is the knob for the current set is lost.  I emailed the seller but my guess it is lost. 

Edit: Model number  :palm:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 04, 2015, 06:00:33 am
Well, that 2020B sure went fast. Looks like it sold for between $100 and $125.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 05, 2015, 04:30:00 am
Another 5020 sold today a few hours after listing. Anyone we know?

http://www.ebay.com/itm/151838460142 (http://www.ebay.com/itm/151838460142)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 05, 2015, 07:22:37 am
Yeah.

I waffled for a while, made a best offer, waffled a while longer, noticed someone else had made an offer, started to buy-it-now, waffled, started-to-buy it now...

So, yeah, it took me a few hours to pull the trigger.

Part of what pushed me over the edge to just paying what they were asking is that it looks like they have some original manuals for the both the 5020/ 2020b and also the 6050, and so I saw it as an opportunity to make and share publish some higher quality scans.

I wondered if the person listing it might be a member here, since they opened it, and took some pictures of the LM399H, LM358H, and the pass transistors, one of which appears to be a replacement.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 05, 2015, 08:02:52 am
LOL! I had a sneaking suspicion it might have been you, eas. Well, I waffled more than you did because I only went so far as making an offer rather than going for the asking price, although I thought about it too. The manuals are a nice bonus, alright. Congrats on your new addition! I look forward to hearing all about it when it arrives.

Some of the things that held me back (which you can soon help shed some light on):

- Not sure if that mV counter knob is original. I haven't seen a lot of 5020's, but I wasn't too concerned about it.

- Silkscreen wearing off the voltage dials. As far as I could tell, they aren't engraved (except maybe on one of the dials), so not sure how best to restore them (scrub the rest off and glue on a laser-printed transparency?). It'd be nice to have my own engraver for stuff like this and for making panels. Robrenz did an amazing job engraving and filling the lettering on Tek scope buttons during one of his restorations.

- No photos of the rest of the case. From the rear view, it appeared that there might be a fair amount of rust and missing paint. That leads to wondering about what dents might also exist.

- No photos of it in operation, not even just turned on. However, the vref looked fine, all the rear jumpers were present, and the fuse cover was still present.

- Odd misalignment of the voltage dials. Since I don't have any hands-on time with the precision models, I don't know what that could mean. Maybe just a silkscreen misalignment? Maybe a broken switch?

You know, we've got to stop meeting on eBay like this. People might start talking. :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: onlooker on October 05, 2015, 12:46:19 pm
I have a 5020.

Quote
- Not sure if that mV counter knob is original. I haven't seen a lot of 5020's, but I wasn't too concerned about it.

The mV adjustment knob looked the same. It has a black knob with a silver dial and a black lock level.

Quote
- No photos of it in operation, not even just turned on. However, the vref looked fine, all the rear jumpers were present, and the fuse cover was still present.

Ebay listed it as for parts(?).

Quote
- Odd misalignment of the voltage dials. Since I don't have any hands-on time with the precision models, I don't know what that could mean. Maybe just a silkscreen misalignment? Maybe a broken switch?

Mine also slightly misaligned like that. I tried to align them and did not improve much. It did not affect the function in any way otherwise.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 05, 2015, 07:29:22 pm
The mV adjustment knob on my 5020 also looks like that. I think it was original, but I have a nice brushed aluminum Kilo counter knob that I'll probably replace it with.

The misaligned voltage dials are probably a result of slippage. Most of my PD Precision supplies have been a little out of wack, and most of them have been noticeably loose. Loosening the set screws, realigning, and tightening again fixes the problem.

Not sure what, if anything, I'll do about the worn labeling. If I can get some of the old rub-on lettering in a suitable typeface I might try that, and cover it with a coat of protective matte clearcoat.

As for the case, I admit I didn't look too closely at what little was shown. Now that you mention it, I definitely see the signs of chipping/rust. I'm not too worried about dents. I've been pretty successful at banging things out with a hammer and hardwood blocks, though most of my experience is with aluminum, rather than steel. As for the rust, the 5020 I already have was/is somewhat rusted on the case, and the top surface of the transformer core. I'll probably repaint it at some point, but for now, cleaning it off with a melamine sponge and applying some light mineral oil has been enough to stabilize things.

For some sellers "for parts, not working" just means that they don't have the skills / equipment to do proper tests and/or that their business is focused more on volume than maximizing value. For others though, they really mean it. Given that this seller knew enough to show the critical precision components, I think they probably ascertained that it wasn't operational. On the other hand, they may not have gone to the effort to do any troubleshooting. I'll post updates once I have the unit in hand. My hope is that its just a fuse. My fear is that it is the transformer.

Once I receive this supply, with its bubble meter, I feel my collection will cover major variations in the PD Precision Supplies. My 2020s have the proprietary ovenized reference and the old rounded-square GE meter. This 5020 will has the vertical bubble meter (Yokogawa?) and an LM399. My PD 2020b and my existing 5020 have the flat vertical meter and LM399. I think one result is that I have fewer reasons to hold on to any of my 2005a supplies, since the my higher current/voltage supplies cover the same functional and aesthetic territory. Perhaps I'll keep one, just to have an example from the early 70s. In any case, I'll probably finish troubleshooting and functional restoration of those supplies before unloading either or both of them. When I am ready to sell them, I'll let people here know.


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 05, 2015, 08:10:39 pm
I have a 5020.

Thanks for the confirmations relative to your unit, onlooker.

Quote
Ebay listed it as for parts(?).

Yes, though that means many different things, as eas mentioned in his reply. If it had some signs of life, I'd have been more willing to just pay the asking price. Fortunately, there was a photo of the primary components, so at least it wasn't just a shell.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 05, 2015, 08:14:08 pm
Thanks for your interpretations, eas. Since you've had hands-on time with the precision versions, you're in a better position than I am to assess the risk of a "parts" unit. Glad you got it.

Do you already have lots of high resolution photos of your mini museum? You're getting a great collection going.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JBeale on October 12, 2015, 10:58:00 pm
Has anyone seen the 2015 Horowitz & Hill "Art of Electronics" 3rd ed. chapter on power supplies? They tested a lot of them including Agilent, etc. and the quietest model (apart from a lead-acid battery) was a Power Designs model.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 13, 2015, 12:20:25 am
Has anyone seen the 2015 Horowitz & Hill "Art of Electronics" 3rd ed. chapter on power supplies? They tested a lot of them including Agilent, etc. and the quietest model (apart from a lead-acid battery) was a Power Designs model.

I haven't, but I am interested to know more about the comparison, especially which models were compared. I took a look at the table of contents and it looks like chapters 8 and 9 are likely to contain that info. Chapter 8 covers noise and 9 is primarily about power supply design. Chapter 9 is available online, but I don't see any comparison of commercial products in there. However, there is a table about various types of batteries.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on October 13, 2015, 12:35:29 am
Has anyone seen the 2015 Horowitz & Hill "Art of Electronics" 3rd ed. chapter on power supplies? They tested a lot of them including Agilent, etc. and the quietest model (apart from a lead-acid battery) was a Power Designs model.

It's in Figure 8.123 on p. 580. The PD4010 is a winner! They measured 1.2 uV rms for their 1967 vintage unit.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 13, 2015, 01:14:13 am
Nice! I don't think I've seen a 4010, yet.

Correction! Tim restored a 4010 precision supply. https://www.eevblog.com/forum/buysellwanted/fs-power-designs-4010-40v1a-precision-power-supply/ (https://www.eevblog.com/forum/buysellwanted/fs-power-designs-4010-40v1a-precision-power-supply/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on October 13, 2015, 03:15:19 am
Has anyone seen the 2015 Horowitz & Hill "Art of Electronics" 3rd ed. chapter on power supplies? They tested a lot of them including Agilent, etc. and the quietest model (apart from a lead-acid battery) was a Power Designs model.

It's in Figure 8.123 on p. 580. The PD4010 is a winner! They measured 1.2 uV rms for their 1967 vintage unit.

Cool! I hadn't looked at that figure before The HP 6114 is not far behind at 2 uV. Hooray for vintage power supplies!

I need to check my PD 2005A and 2010 to see how they compare.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on October 13, 2015, 04:43:37 am

Quote
They measured 1.2 uV rms for their 1967 vintage unit.

Is this 1.2 ripple?

Can a Rigol DZ1054Z measure this 1.2 uV easily?  How to hook up? I am worried about stray signals.  And would this ripple be 60 Hz?  I tried to measure my 5020 once and failed because of noise.

If I ask this question under General, I will probably be laughed off this forum  :-DD

thanks

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 13, 2015, 04:48:49 am
Yes, ripple. I don't think the 1054z is quiet enough to see it, but I don't recall what the exact noise floor is. There's sure to be a post about it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 13, 2015, 07:00:15 am

Quote
Quote
They measured 1.2 uV rms for their 1967 vintage unit.

Is this 1.2 ripple?

Can a Rigol DZ1054Z measure this 1.2 uV easily?  How to hook up? I am worried about stray signals.  And would this ripple be 60 Hz?  I tried to measure my 5020 once and failed because of noise.

If I ask this question under General, I will probably be laughed off this forum  :-DD


1. The DZ1000z series has, at best, 1mv resolution. Dynamic range is, what 10mv? The ADC has 8-bits of resolution. so, that's 10mV/256 = ~40uV resolution. Unless I've had a major lapse of brian-thingyness, it doesn't sound promising, at least not without a low noise pre-amp.

2. How to hook up?
https://www.youtube.com/watch?v=Edel3eduRj4 (https://www.youtube.com/watch?v=Edel3eduRj4)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 13, 2015, 07:44:25 am

1. The DZ1000z series has, at best, 1mv resolution. Dynamic range is, what 10mv? The ADC has 8-bits of resolution. so, that's 10mV/256 = ~40uV resolution. Unless I've had a major lapse of brian-thingyness, it doesn't sound promising, at least not without a low noise pre-amp.


i.e., if you can see the ripple on your 1054z, the PD precision supply is waaay out of spec.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on October 13, 2015, 04:21:29 pm

1. The DZ1000z series has, at best, 1mv resolution. Dynamic range is, what 10mv? The ADC has 8-bits of resolution. so, that's 10mV/256 = ~40uV resolution. Unless I've had a major lapse of brian-thingyness, it doesn't sound promising, at least not without a low noise pre-amp.


i.e., if you can see the ripple on your 1054z, the PD precision supply is waaay out of spec.

Thanks bitseeker and eas.  Now I do not feel so bad.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on October 13, 2015, 05:40:00 pm
Well, that 2020B sure went fast. Looks like it sold for between $100 and $125.

I've got a 2020B I am going to sell at some point on eBay.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on October 13, 2015, 09:35:17 pm
Cool. What compelled you to sell it? Collection getting too big?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on October 22, 2015, 11:20:03 pm
The PD 5020 came last week. I unpacked it and checked it over. The case is in pretty good shape, there are some rusted nicks, but not as many as on the case of my first 5020. I didn't see any obvious problems with any of the components, but when I powered it on, the AC light turns on, but is no output and the meter doesn't move. I haven't started troubleshooting it yet, beyond confirming the internal fuse was intact.

None of this was a surprise. The seller listed it as "For Parts/Repair" and knew enough to photograph the LM399 and pass transistors to show what physical state they were in. I bought it because the higher voltage/current precision supplies don't come up very often in working condition, or otherwise, the price was reasonable, and it came with not one, but three different printed manuals. Two different versions of the 5020 and one for the 6050.

The two 5020s manuals aren't identical, they are different versions.

The first seems to date from right around the original release of the 5020. It includes a number of pages that seem to have originated on a high-quality dot matrix printer. These cover the technical specs and parts list for the 5020. One prefaces the pages with the general description, operating instructions, and theory of operation with the explanation that the 5020 is an improved version of the 4010. The following pages are xeroxes of typewritten pages and refer to the 4010. The schematics at the end are for the 5020.

The second 5020 manual also covers the 2020b and C500. It seems to be of similar or identical vintage (Both have Rev G schematic drawings) to the scanned manual for those supplies I found online earlier this year. The image quality of my scan is much better, and they also have hidden OCRed versions of the text for searchability (not such a big deal on smaller manuals like these, but still nice to have)

I took some time to make high-quality scans of all three manuals, and I've posted them on my site (link below). I haven't uploaded them to KOBB or elsewhere yet. If someone else wants to, that's fine, though I'd hold for a week because I might post updates if I can manage to reduce the file-size significantly without a significant loss of quality. Right now they are about 30MB each.


I hope people find them useful.

If anyone has good printed manuals for any other PD supplies, it would be great if you could make good quality scans of at least the diagrams and share them. I'm personally looking for complete (or any) docs for the 2020 precision supply, and 6050a, 5005T, and 6010 bench supplies. I'd also love better quality versions of the TP340a and 2005a precision supply manuals.

Speaking of the 2005a, there is a complete manual/schematic available online, but the component layout diagram doesn't match the boards in my 2005a supplies, which both appear to have the same PCB but manufactured a few years apart. I've started trying to reverse-engineer my own annotated layout diagram, but if someone else has one, it would be great to see it and see if it saves me some trouble.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: fpliuzzi on October 23, 2015, 01:45:59 am
Thanks eas for taking the time to scan some of the Power Designs manuals. The 6050 manual will come in handy when I get the time to look into an anomaly in my 6050A.

Prior to your contribution, all I was able to find online was a fuzzy scan of the 6050A's schematic and another site had a copy of the supply's spec sheet.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on October 23, 2015, 02:15:30 am
Thanks for scanning and posting your manuals.  :-+  Excellent quality too. :clap:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on October 25, 2015, 10:19:23 pm
Does anyone have the manual or schematic for the 4050? It's my first (and only, so far) power supply and I would like to have some sort of reference to go by if I ever need to repair it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on November 10, 2015, 11:54:18 pm
I've been saving every PD manual PDF I come across, but I don't have one for the 4050. There are some out there for the 3650, which I think is the previous generation of that model.

People interested in the precision supplies would do well to look on eBay right now. After a lean period, there are currently multiple units at reasonable prices.
I will say that this 2020b (http://www.ebay.com/itm/Power-Designs-Precision-Dc-Power-Supply-Model-2020B-0-20V-0-2A-LOAD-TESTED-/272015224731) looks like one of the last of the old-style precision supplies. Don't be fooled by it at first glance, there are some obvious compromises in build quality, probably a result of both cost cutting, and discontinued products from suppliers.

There is also a late model 2040a for $129. It has none of the physical charm of the older units. It's in an off-the-shelf plastic enclosure that I've seen used on some ESI (or was it IET) equipment. The decade dials are thumbwheels. The only thing to recommend it is that it can output 4A, and, I assume still has the precision and stability of the older models.



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: jeffsf on December 02, 2015, 11:40:42 pm
Thanks to @nanofrog at pointing me in the direction of these older Power Designs supplies! With a couple of these in hand, I'm getting back to the point where my equally vintage skills can be applied again.

One of mine came without feet. Has anyone located a current source for appropriate screw-through rubber feet?

(I've also got some Collins S-Line gear that will need a few.)

Edit:

Looks like Budwig is perhaps the lone remaining US manufacturer of these kind of feet
http://budwigmoldedproducts.com/rubber-bumpers/ (http://budwigmoldedproducts.com/rubber-bumpers/)

One potential supplier of small quantities is https://www.westfloridacomponents.com/screw-on-recessed-bumpers.html (https://www.westfloridacomponents.com/screw-on-recessed-bumpers.html)
(I have not done more but find them on the Web.)

Budwig has suggested that Linear Motion Labs may be able to supply small quantities. I haven't contacted them yet.
1.866.888.4006
http://linearmotionlabs.com/ (http://linearmotionlabs.com/)

Edit:

OK, I'll admit I apparently still haven't mastered the Digikey "catalog" and often wish they had a current PDF version

Another option might be the Keystone 728 -- http://keyelco.com/userAssets/file/M65p134.pdf (http://keyelco.com/userAssets/file/M65p134.pdf)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rdl on December 03, 2015, 01:30:36 am
You can find rubber feet like that on ebay, but maybe not the exact shape of the originals and smaller sizes are not that common.

http://www.ebay.com/sch/i.html?&_nkw=rubber+feet+recessed (http://www.ebay.com/sch/i.html?&_nkw=rubber+feet+recessed)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on December 15, 2015, 02:51:45 am
I bought an original Power Designs 2020 Precision Power Source manual and it arrived today. I made high quality scans of all the pages, including 600dpi scans of the tabloid-sized schematics and component diagrams.

I've turned them into a searchable PDF, uploaded them to my site, and linked them from my page of Power Designs manuals (http://techobsessed.net/power-designs-manuals-and-schematics/). The page also links to previously uploaded original high quality scans of manuals for the 5020 and 2020b precision supplies, and the 6050.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 15, 2015, 03:08:56 am
Thanks, eas!  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on December 15, 2015, 04:20:14 am
Thanks, eas!  :-+
I concur.   :) Very nice indeed.  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on December 15, 2015, 04:45:14 am
Yes, thanks eas. I recently picked up a 2010  to keep my 2005A company. I can't find a manual for it online but the 2020 manual is probably close enough.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on December 15, 2015, 05:38:04 am
No oven light on that 2010? Probably uses an LM199 or LM399 rather than the old custom Power Designs ovenized reference amplifier used in the 2020. My guess is that it may be closest to the 2020b and 5020.

The 2020 I posted the manual for is a similar vintage to the 2005, but uses Power Designs "heatrans" technology which includes power resistors as part of the dissipative element.

My pleasure, Bitseeker and Nanofrog!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 15, 2015, 11:53:12 pm
Yes, thanks eas. I recently picked up a 2010  to keep my 2005A company. I can't find a manual for it online but the 2020 manual is probably close enough.

I recently picked up a 2010, too. Yours is better looking, mtdoc.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: MaxFrister on December 16, 2015, 05:38:19 am
I've turned them into a searchable PDF, uploaded them to my site, and linked them from my page of Power Designs manuals (http://techobsessed.net/power-designs-manuals-and-schematics/). The page also links to previously uploaded original high quality scans of manuals for the 5020 and 2020b precision supplies, and the 6050.

How did you make the pdf searchable. I've strougle with some huge but unsearchable pdfs in the past.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JoeO on December 16, 2015, 01:47:45 pm
I've turned them into a searchable PDF, uploaded them to my site, and linked them from my page of Power Designs manuals (http://techobsessed.net/power-designs-manuals-and-schematics/). The page also links to previously uploaded original high quality scans of manuals for the 5020 and 2020b precision supplies, and the 6050.

How did you make the pdf searchable. I've strougle with some huge but unsearchable pdfs in the past.
I use Adobe Acrobat 9 Standard.  It came with my scanner.
Once the document is scanned in as a pdf, the OCR software runs to make it searchable.
The accuracy is dependent upon the quality of the document that is scanned.  It is not perfect but it does an excellent job of OCRing. 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on December 17, 2015, 12:32:12 am
My scanner came bundled with a version of Abbyy FineReader. It does OCR and stores the converted text as a transparent layer to allow searching and copy/paste. Its a great way to work with the limitations of OCR. It isn't an uncommon feature, these days.

I'd like to find some inexpensive OS X software to allow me to add a hyper-linked table of contents to scans, but I haven't looked very hard.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 18, 2015, 06:44:06 pm
Anyone know where I can find a manual for the 5005R? It seems to be an oddball with no manual to be had...

Update: Found it, in case anybody else is looking for it, it is obscurely included in the TW5005T manual:

http://www.nscainc.com/uploads_2014/product_guides/POW_TW5005.pdf (http://www.nscainc.com/uploads_2014/product_guides/POW_TW5005.pdf)


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 18, 2015, 06:56:27 pm
I guess they were cutting back on the cost of printing manuals even more than slipping in the R version. In the one you linked to, they just inserted a note, "Where reference is made to models 5005R and TW5005 in Section 1 and Section 2 of the following manual, substitute model numbers 5005T and TW5005T."
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 18, 2015, 07:04:05 pm
I guess they were cutting back on the cost of printing manuals even more than slipping in the R version. In the one you linked to, they just inserted a note, "Where reference is made to models 5005R and TW5005 in Section 1 and Section 2 of the following manual, substitute model numbers 5005T and TW5005T."

"All instructions in this manual apply equally to the Model 5005R and to both sections of the model TW5005T."

I had to fish through it to make sure it applies...

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 18, 2015, 07:20:14 pm
Yeah, there are so many models of PD supplies and then variations of them to boot.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 18, 2015, 07:31:08 pm
Yeah, there are so many models of PD supplies and then variations of them to boot.

I got this one for a song (http://item.ebay.co.uk/301828710191?item_hash4=b3e767fe&LH_Complete=1&LH_BIN=1&LH_BO=1&_ipg=200&_pgn=1&rc=nt&rmvSB=true), because it's older than dirt and is lacking remote sense. I just hope I can get the thing to work. I'll probably wind up using it to "burn in" 5 ppm resistors and voltage references into the thousands of hours of on time range. That's pretty much all I use my PD supplies for - a damn shame.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 18, 2015, 07:37:44 pm
Cool. It should clean up nicely too -- not all banged up like some I've seen.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 18, 2015, 07:45:56 pm
Cool. It should clean up nicely too -- not all banged up like some I've seen.

I'll post pics after I get it to work and clean it up.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 22, 2015, 03:52:42 am
How do you clean the big old pots on these things. I am getting voltage spikes up the wazoo trying to adjust the voltage setting. Do you have to actually open them up and spray them?

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 22, 2015, 03:40:49 pm
How do you clean the big old pots on these things. I am getting voltage spikes up the wazoo trying to adjust the voltage setting. Do you have to actually open them up and spray them?

Any thoughts?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 22, 2015, 06:43:32 pm
Are you referring to the Bournes multi-turn pots? I had a busted one in my TP340A and tried to fix it, but the contact inside is fiddly and never behaved correctly at the limits. So, if you do open one to clean inside, it may or may not work correctly afterward. It might be OK if you just pop the rear cap off to flush it with contact/electronics cleaner.

I don't know what the single-turn pots are like inside.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 22, 2015, 06:45:14 pm
Are you referring to the Bournes multi-turn pots? I had a busted one in my TP340A and tried to fix it, but the contact inside is fiddly and never behaved correctly at the limits. So, if you do open one to clean inside, it may or may not work correctly afterward. It might be OK if you just pop the rear cap off to flush it with contact/electronics cleaner.

I don't know what the single-turn pots are like inside.

Yep, I'm talking about the multi-turn pots that are some two inches in diameter and quite thick. I see that there are metal tabs in impressions holding the metal back to the sides and was wondering if I need to deform these tabs to take the back off and then flush the insides with potentiometer cleaner. Or, is there an easier way to pop the rear cap off or do this without any disassembly of the pots?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 22, 2015, 07:06:05 pm
The housings on mine were all plastic. No metal tabs.

I haven't yet opened my 2010 precision supply, but it might have one like you describe since it's older than the TP340A. The other PD supplies I have use single-turn pots.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 22, 2015, 07:08:53 pm
I see that there are metal tabs in impressions holding the metal back to the sides and was wondering if I need to deform these tabs to take the back off

That sounds very similar to the all-plastic pots. See if you can lift each tab without permanently deforming it and ease the cover off in order to minimize hardening the metal.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: eas on December 24, 2015, 05:11:45 am
I think someone (robertz?) mentioned that he drilled one or two small holes in the ends of the pot housing, used a syringe to inject contact cleaner cleaner, blew it out with compressed air, repeated if necessary, and then added some electrical lube through the same holes.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 27, 2015, 02:01:01 am
Well I opened up the Power Designs 5005R  in an effort to repair it. Let me start by giving you some background:

This model is fairly old like most Power Designs supplies and has a low granularity (coarse) single turn voltage knob (0-50V) with a higher precision single turn 0-1 V control knob inside of it. Inside the unit, there are two pots piggy back mounted with the fine on top and the coarse on the bottom. It was a real bitch trying to separate them to clean them. The two pots are wired in series and the sum of their resistance is presented to the voltage regulation circuit.

Now, the problem presented itself when I tested the unit. Because all of these analog pots are older than dirt, tiny crap inevitably got inside of them. The result of this is a very VERY serious problem. To make matters worse, the main voltage control pot is not wirewound. It has a solid circular (ring) resistive metallic (or more likely ceramic because it's a Cermet pot) element inside and offered (notice the past tense here) seemingly true contiguous adjustment. Unfortunately, because the thing is older than dirt, crap managed to get inside of it, whether it's the lube used to lubricate it (and there's quite a bit in there) or metal/ceramic dust from too many turns or the environment (or whatever). So, when the wiper (which is tiny and barely makes contact with the resistive element) gets dirt between it and the smooth track, guess what happens? Basically, you get a "break before make" open circuit scenario telling the supply to shoot a full fifty volts to its output terminals. So, any reasonable circuit you have connected, save for your current limit setting, gets instantly fried. This made me appreciate modern digital circuits with rotary encoders providing inputs to microcontrollers (i.e., solving this entire problem).

I first noticed the spikes when I tried to test the supply through its entire 50 volt range. As I turned the coarse voltage control pot from 0 to 50, I saw occasional brief spikes to 50 V along the way. More surprisingly, the fine tune control (which has a wirewound pot backing it) also caused spikes. This behavior makes the supply not only useless, as is, but also dangerous, both to DUTs and small furry animals. One can argue that you can set the voltage first and then connect a circuit or device, but I feel that this is too much to ask and a mere touch of the voltage control pot can shoot a 50+ V spike (i.e., infinite resistance in the regulation circuit) through the device connected to it, because a single grain of crap got under the wiper or it (i.e., the wiper) left the resistive element for ten milliseconds due to vibration and tight tolerance (combined with a crap speed-bump it was balancing on partially).

I tried to take the pots apart and clean them, but this was futile. The things are just way too old and the tolerances too tight inside. They were never meant to be taken apart and cleaned. There's lube inside and the wiper is at such tight tolerance with the cermet track that any shift when it is taken apart will result in more of that "break before make" action when put back together. It's just not worth the effort and danger. I certainly would not trust any sort of "drill holes, blow and clean solution," because even if it works perfectly on day one, all it takes is for a single particle to get in between the wiper and track and your circuit under test is literally toast.

So, the solution to the dilemma was to take a single 10 kOhm Chinese Bourns imitation 10-turn pot and replace the two (coarse and fine) with the single multi-turn pot. Sadly, the hole in the metal front panel was too small and I had to drill it slightly larger to fit the fake Bourns pot. The whole endeavor including removing the old pots, examining them and mounting the fake Bourns took about two hours.

In the end, this seems to have worked fine and allows, with some manual dexterity, adjustment on the order of about 5-10 mV. Also, there is no longer a "break before make issue," because with a new non-corroded, non-polluted wirewound pot, it's always "make before break." My only concern is not knowing how many watts of power are being placed through the pot itself to make sure that this is within the 0.6 W or so that it is rated for. In a conventional voltage regulator circuit, the current flowing between the Adj and Out pins is tiny. In this particular supply's circuit, who knows...

I have two TW4005 dual-supplies I got recently that need similar treatment due to the same voltage spike issue when the coarse control is turned. The bottom line is that unless you are willing to replace the pots on Power Designs analog supplies that use pots for regulation (i.e., the non-precision supplies), they are a bad idea (to buy). Even on the precision units, you absolutely must properly clean the switch contacts for them to work properly and without danger. All it takes is one open circuit caused by "crap interference," even in a switch designed to make before break, and you can kiss your DUT goodbye.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on December 27, 2015, 03:18:21 am

So, the solution to the dilemma was to take a single 10 kOhm Chinese Bourns imitation 10-turn pot and replace the two (coarse and fine) with the single multi-turn pot. Sadly, the hole in the metal front panel was too small and I had to drill it slightly larger to fit the fake Bourns pot. The whole endeavor including removing the old pots, examining them and mounting the fake Bourns took about two hours.

In the end, this seems to have worked fine and allows, with some manual dexterity, adjustment on the order of about 5-10 mV.

Hey, waaaiiit a second.  Didn't you  raise a ruckus about these fake pots, contact the FTC, Bournes, etc (https://www.eevblog.com/forum/projects/fighting-chinese-sellers-of-counterfeit-parts-on-ebay/) to try and prevent them being sold.  Now it turns out (no pun intended) that after getting a refund, one of them was used to fix your power supply.  What the .. ???
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 27, 2015, 04:37:47 am

So, the solution to the dilemma was to take a single 10 kOhm Chinese Bourns imitation 10-turn pot and replace the two (coarse and fine) with the single multi-turn pot. Sadly, the hole in the metal front panel was too small and I had to drill it slightly larger to fit the fake Bourns pot. The whole endeavor including removing the old pots, examining them and mounting the fake Bourns took about two hours.

In the end, this seems to have worked fine and allows, with some manual dexterity, adjustment on the order of about 5-10 mV.

Hey, waaaiiit a second.  Didn't you  raise a ruckus about these fake pots, contact the FTC, Bournes, etc (https://www.eevblog.com/forum/projects/fighting-chinese-sellers-of-counterfeit-parts-on-ebay/) to try and prevent them being sold.  Now it turns out (no pun intended) that after getting a refund, one of them was used to fix your power supply.  What the .. ???

Yep, you are right. It just so happens that this 10k version I bought knowing full well it's a fake, it wasn't advertised as genuine and came with a ten turn indicator (and I had to pay $1.50 for shipping). So, the seller didn't really lie about anything in the listing, although it does say Bourns on the back of the pot. If you look carefully at the link to my prior post that you yourself provided, you will notice that the items pictured were 2k pots (1k and 5k units were also part of that purchase).

I didn't refund this 10k pot, since there was no pre-conceived notion or advertisement of authenticity and therefore I felt no desire in making the seller refund and take a loss. If I really wanted to pursue this, I could have easily gotten a refund under eBay's "no counterfeit goods" policy, but I am fair to sellers that don't make false claims in their listings, even if they still sell counterfeit "junk" for counterfeit junk prices.

So far, the pot is working pretty well. I don't expect it to last through 100,000 turns though...

My goal in the prior post was not so much eliminating the fakes off of eBay, it was about punishing sellers that market fakes as genuine/original goods and/or post BS specs that are not even remotely accurate. Those are the ones I go after when I feel like "making them pay for scamming us." Counterfeit good will always be sold, but claiming they are originals, that's where I draw the line on punishment. The "notifying the FTC and Bourns" were just scare tactics used on the seller when he insisted they were genuine and wanted me to send them back at my cost. Of course if he persisted, I would have definitely sent all the pics and info I collected to eBay and would have still gotten a refund, as I did with the boost converters mentioned several pages down in that forum post when the (other) seller began to act like an ass.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on December 27, 2015, 06:36:35 am
It's all good. I was just tugging on your (Sharp)ears.  :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Joule Thief on December 27, 2015, 07:51:00 am
I have a PDS 5005 coming next week to add to the bench. I will be on the lookout for noisy pots.

I just refurbed an older HP 6113A displaying noise while setting the output voltage with the 0 - 100 uV control.

Upon disassembly of the control (pic below), dried lube was the culprit. The dried lube cleaned off easily with IPA and a light coating of Rheo-Lube returned the performance to being repeatable at the 10 uV level. I hope the PDS supply is just as accessible

 :-+

.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on December 27, 2015, 08:57:54 am
So who on here bought the 2020(B???) on ebay?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 27, 2015, 02:35:27 pm
So who on here bought the 2020(B???) on ebay?

That was a very good deal on it. If I didn't have one already, I might have jumped on it. I am not too big of a fun of it now that I have one, because the 1 million and 1 switch contacts take forever to clean and they do need to be cleaned.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 27, 2015, 02:37:27 pm
I have a PDS 5005 coming next week to add to the bench. I will be on the lookout for noisy pots.

Cermet pots are a whole different ball game, one dust particle = "infinite" voltage through your circuit... If you do get a 5005, please report back on what you did.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Joule Thief on December 27, 2015, 08:44:15 pm
I have a PDS 5005 coming next week to add to the bench. I will be on the lookout for noisy pots.

Cermet pots are a whole different ball game, one dust particle = "infinite" voltage through your circuit...

Maybe we should look into design and construction of an add-on (or add-in) adjustable crowbar over volt protector for the smaller, higher voltage PDS supplies?

a "micro bar" to borrow from an EEV Blog theme.   :-DD


http://www.onsemi.com/pub_link/Collateral/MC3423-D.PDF (http://www.onsemi.com/pub_link/Collateral/MC3423-D.PDF)


I know Lambda used to offer these as an attachment to be bolted on to the rear panel of some models of their supplies.

https://www.surplussales.com/Semiconductors/pdf/ps-lmov-2.pdf (https://www.surplussales.com/Semiconductors/pdf/ps-lmov-2.pdf)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 27, 2015, 10:48:47 pm
I have a PDS 5005 coming next week to add to the bench. I will be on the lookout for noisy pots.

Cermet pots are a whole different ball game, one dust particle = "infinite" voltage through your circuit...

Maybe we should look into design and construction of an add-on (or add-in) adjustable crowbar over volt protector for the smaller, higher voltage PDS supplies?

a "micro bar" to borrow from an EEV Blog theme.   :-DD


http://www.onsemi.com/pub_link/Collateral/MC3423-D.PDF (http://www.onsemi.com/pub_link/Collateral/MC3423-D.PDF)

Or just do the sensible thing and not attempt to repair pots that cannot be repaired/cleaned reliably. Put in a multi-turn Bourns pot (or fake version thereof) like I did and be done...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Joule Thief on December 28, 2015, 03:44:24 am
In the "good old days". some pots had multiple contacts on the wiper element in attempt to avoid this scenario.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 28, 2015, 07:34:08 pm
So who on here bought the 2020(B???) on ebay?

Is that the one that was looking a bit long in the tooth and had mismatched dials? Wasn't me. Although I'd like to "upgrade" my 2010 by getting a 2020B, the aesthetics matter too and I didn't want to deal with mismatched parts.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 28, 2015, 07:43:16 pm
Now, the problem presented itself when I tested the unit. Because all of these analog pots are older than dirt, tiny crap inevitably got inside of them. The result of this is a very VERY serious problem. To make matters worse, the main voltage control pot is not wirewound. It has a solid circular (ring) resistive metallic (or more likely ceramic because it's a Cermet pot) element inside and offered (notice the past tense here) seemingly true contiguous adjustment.

Although there probably is a way to resurface those kinds of pots, I never looked into it. I just replace them.

Quote
So, the solution to the dilemma was to take a single 10 kOhm Chinese Bourns imitation 10-turn pot and replace the two (coarse and fine) with the single multi-turn pot.

Cool. I noticed that the imitation 10-turn pots take a little more torque to rotate than the genuine ones, but I find that to be a good thing for voltage controls (i.e., minimize accidents).

Quote
My only concern is not knowing how many watts of power are being placed through the pot itself to make sure that this is within the 0.6 W or so that it is rated for. In a conventional voltage regulator circuit, the current flowing between the Adj and Out pins is tiny. In this particular supply's circuit, who knows...

Yeah, I'd be surprised if there was much going through it. Of course, if you really want to know, "take it apart"...again.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 31, 2015, 12:54:15 am
Does anybody know what an "ammeter electrical zero" adjustment does. I've calibrated the voltage, 50 mA current, 500 mA current settings and there is one more calibration knob called "ammeter electrical zero" and I can't for the life of me figure out what it effects. I tried full load, no load, no voltage, high voltage and that trimmer does absolutely nothing.

What it definitely does not do is control positive, zero or negative current into the load, which is what I thought it would do.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on December 31, 2015, 12:57:05 am
Does it deal with the range switchover on the transformer?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: SharpEars on December 31, 2015, 01:47:26 am
Does it deal with the range switchover on the transformer?

I don't think so. The 100 Ohm (R26) trimmer is just left of center on page 16 of the manual:

http://www.nscainc.com/uploads_2014/product_guides/POW_TW5005.pdf (http://www.nscainc.com/uploads_2014/product_guides/POW_TW5005.pdf)

I found the following in a manual for a completely unrelated piece of equipment. Perhaps it offers a hint as to what an ammeter electrical zero adjustment is for:

Quote
ELECTRIC CORPORATION
VOLT AMPERE TESTER
SUN VAT -40

AMMETER ELECTRICAL
ZERO ADJUSTMENT

This adjustment knob is used to periodically set
the ammeter pointer to the zero (0) line
electronically. When adjusting zero, the TEST
SELECTOR must be set to #2 CHARGING position
with the Load Leads connected to the battery
(Figure 1).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: dom0 on December 31, 2015, 02:43:48 am
Quote
My only concern is not knowing how many watts of power are being placed through the pot itself to make sure that this is within the 0.6 W or so that it is rated for. In a conventional voltage regulator circuit, the current flowing between the Adj and Out pins is tiny. In this particular supply's circuit, who knows...

Yeah, I'd be surprised if there was much going through it. Of course, if you really want to know, "take it apart"...again.

Most single lab supplies are basically inverting amplifiers, so you'll have a positive voltage reference somewhere, often also used to supply the op amps, and a fixed reference resistor to the inverting input (at control loop GND / positive output potential). The pot connects from the same node to the negative output sense line. Power dissipation is easily calculated for this kind of supply, the current is fixed (reference voltage / reference resistor) and the voltage across the pot is the full output voltage. Usually the current is low, about 1-2 mA would be typical for a supply up to 50 V output voltage.

So ideally if you have the schematic you can basically read that info right on it, if you don't the quickest way is to simply connect an ammeter in series with the pot.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 31, 2015, 07:13:45 pm
What it definitely does not do is control positive, zero or negative current into the load, which is what I thought it would do.

Sounds like it just electrically sets the panel meter's needle to read zero amps when no current is flowing, rather than mechanically positioning the needle to zero at the meter movement.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: boborjan on March 19, 2016, 09:24:01 pm
A beginner's question: do PD models that do not have dedicated CC/CV signalling bulb have any means to notify the user when control is switched to CC? Or one should recognize the decreasing voltage level on the meter?
I plan to buy a nice vintage PD supply but I have never used any yet.

thanks,
Viktor
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 19, 2016, 09:46:06 pm
A beginner's question: do PD models that do not have dedicated CC/CV signalling bulb have any means to notify the user when control is switched to CC? Or one should recognize the decreasing voltage level on the meter?
I plan to buy a nice vintage PD supply but I have never used any yet.

I don't believe so. You could probably add this quite easily.

Are you in the US? I have one that I've modified a bit to fix a broken heater. I'm not really using it, and I'd love to see a beginner get some use out of it. I'd be willing to give it to you if you can pay shipping.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: boborjan on March 19, 2016, 10:30:36 pm
First: thanks for the offer. In fact I am sitting in Europe but I do have a US address for shipping. But: I am a newbie to PD supplies only. I am an electrical engineer myself, so maybe you would like to preserve your supply for a real beginner who needs a starter kit.
But still, I am looking for a DC supply for daily use (I am not satisfied with my current one) and I believe keeping these vintage stuff alive is a good thing (and they also look nice). Your offer is thus interesting to me and I am also willing to pay a reasonable price for it (I am currently searching on ebay).
What modifications have you made on your model? I will have to modify my one anyway because of the different input voltage levels here.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 20, 2016, 01:17:44 am
First: thanks for the offer. In fact I am sitting in Europe but I do have a US address for shipping. But: I am a newbie to PD supplies only. I am an electrical engineer myself, so maybe you would like to preserve your supply for a real beginner who needs a starter kit.
But still, I am looking for a DC supply for daily use (I am not satisfied with my current one) and I believe keeping these vintage stuff alive is a good thing (and they also look nice). Your offer is thus interesting to me and I am also willing to pay a reasonable price for it (I am currently searching on ebay).
What modifications have you made on your model? I will have to modify my one anyway because of the different input voltage levels here.

Yes, I was thinking about giving it away as a prize if I ever get around to delivering that presentation on op-amps that I promised last year but have yet to deliver on.

As far as the mods/repairs, the heater coil and thermostat were gone when I got the unit. There were some other minor issues, but nothing major. The heater being out just means that the voltage reference wasn't inside a nice temperature controlled chamber. I rewound the heater with some resistance wire. I didn't want to mess with the mains voltage that was powering the heater, so I have rewired it to the unused phase of the secondary that supplies unregulated DC to the series regulator. The thermostat is just a simple comparator with hysteresis and a MOSFET. It seems to maintain the oven temps with a little better variation than how (I've read) the originals perform, and I am not able to measure any disruption in the output from the heater switching on/off. Of course, my circuit is just a hand-soldered protoboard mounted to the main PCB via some screws, standoffs, and holes I drilled in the PCB. Not pretty, but functional.

If you're OK with voltage adjustment via a potentiometer, there are lots of the older HP supplies like the 6237B on eBay for very cheap. IMHO the nicest "vintage" supplies are the HP 6114A and 6115A. I've repaired and completely refurbished several of these, and I love them and will never part with them :) They are really scarce now, but if you're not in a hurry, put a watch on eBay. Unfortunately, there are a few sellers up there with completely ridiculous asking prices and what amount to permanent auctions on these. This tends to mislead the usual eBay surplus scavengers into thinking that's what they can get for the partially functional or physically damaged units that they bought for next to nothing. But if you watch, you can still occasionally find one at a reasonable price, or maybe even talk a seller down by showing him what they actual sell for. The last one I bought I paid $75 (shipped). This is all eBay US, so maybe the situation is different where you are.

There are other good, but inexpensive, supplies out there, I am sure. This might be a good topic for a separate thread on the forum. Another option, if you want a project, is to get one of these old supplies and scrap everything except the chassis, KV divider, and transformer. Building a very good quality series regulator is not very complicated with all the wonderful ICs out there now.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: iampoor on March 20, 2016, 08:26:10 pm
First: thanks for the offer. In fact I am sitting in Europe but I do have a US address for shipping. But: I am a newbie to PD supplies only. I am an electrical engineer myself, so maybe you would like to preserve your supply for a real beginner who needs a starter kit.
But still, I am looking for a DC supply for daily use (I am not satisfied with my current one) and I believe keeping these vintage stuff alive is a good thing (and they also look nice). Your offer is thus interesting to me and I am also willing to pay a reasonable price for it (I am currently searching on ebay).
What modifications have you made on your model? I will have to modify my one anyway because of the different input voltage levels here.

Yes, I was thinking about giving it away as a prize if I ever get around to delivering that presentation on op-amps that I promised last year but have yet to deliver on.

As far as the mods/repairs, the heater coil and thermostat were gone when I got the unit. There were some other minor issues, but nothing major. The heater being out just means that the voltage reference wasn't inside a nice temperature controlled chamber. I rewound the heater with some resistance wire. I didn't want to mess with the mains voltage that was powering the heater, so I have rewired it to the unused phase of the secondary that supplies unregulated DC to the series regulator. The thermostat is just a simple comparator with hysteresis and a MOSFET. It seems to maintain the oven temps with a little better variation than how (I've read) the originals perform, and I am not able to measure any disruption in the output from the heater switching on/off. Of course, my circuit is just a hand-soldered protoboard mounted to the main PCB via some screws, standoffs, and holes I drilled in the PCB. Not pretty, but functional.

If you're OK with voltage adjustment via a potentiometer, there are lots of the older HP supplies like the 6237B on eBay for very cheap. IMHO the nicest "vintage" supplies are the HP 6114A and 6115A. I've repaired and completely refurbished several of these, and I love them and will never part with them :) They are really scarce now, but if you're not in a hurry, put a watch on eBay. Unfortunately, there are a few sellers up there with completely ridiculous asking prices and what amount to permanent auctions on these. This tends to mislead the usual eBay surplus scavengers into thinking that's what they can get for the partially functional or physically damaged units that they bought for next to nothing. But if you watch, you can still occasionally find one at a reasonable price, or maybe even talk a seller down by showing him what they actual sell for. The last one I bought I paid $75 (shipped). This is all eBay US, so maybe the situation is different where you are.

There are other good, but inexpensive, supplies out there, I am sure. This might be a good topic for a separate thread on the forum. Another option, if you want a project, is to get one of these old supplies and scrap everything except the chassis, KV divider, and transformer. Building a very good quality series regulator is not very complicated with all the wonderful ICs out there now.

If you ever decide to give that supply away I will sign up. I have been wanting to get a Power Designs supply for awhile, and my current bench supply is really starting to act up. Oh and Im also a relative beginner. I just like high quality gear that you can actually repair (My background is in technician work).

Those HP supplies look beautiful. Remind me of this one...
http://www.ebay.com/itm/272157564667?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/272157564667?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
What are some general usages of a supply with so much precision? Maybe setting bias currents on transistor pairs? Most of the opamp circuitry I have worked with hasnt been too fussy (yet atleast  >:D)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 21, 2016, 04:10:22 am
First: thanks for the offer. In fact I am sitting in Europe but I do have a US address for shipping. But: I am a newbie to PD supplies only. I am an electrical engineer myself, so maybe you would like to preserve your supply for a real beginner who needs a starter kit.
But still, I am looking for a DC supply for daily use (I am not satisfied with my current one) and I believe keeping these vintage stuff alive is a good thing (and they also look nice). Your offer is thus interesting to me and I am also willing to pay a reasonable price for it (I am currently searching on ebay).
What modifications have you made on your model? I will have to modify my one anyway because of the different input voltage levels here.

Yes, I was thinking about giving it away as a prize if I ever get around to delivering that presentation on op-amps that I promised last year but have yet to deliver on.

As far as the mods/repairs, the heater coil and thermostat were gone when I got the unit. There were some other minor issues, but nothing major. The heater being out just means that the voltage reference wasn't inside a nice temperature controlled chamber. I rewound the heater with some resistance wire. I didn't want to mess with the mains voltage that was powering the heater, so I have rewired it to the unused phase of the secondary that supplies unregulated DC to the series regulator. The thermostat is just a simple comparator with hysteresis and a MOSFET. It seems to maintain the oven temps with a little better variation than how (I've read) the originals perform, and I am not able to measure any disruption in the output from the heater switching on/off. Of course, my circuit is just a hand-soldered protoboard mounted to the main PCB via some screws, standoffs, and holes I drilled in the PCB. Not pretty, but functional.

If you're OK with voltage adjustment via a potentiometer, there are lots of the older HP supplies like the 6237B on eBay for very cheap. IMHO the nicest "vintage" supplies are the HP 6114A and 6115A. I've repaired and completely refurbished several of these, and I love them and will never part with them :) They are really scarce now, but if you're not in a hurry, put a watch on eBay. Unfortunately, there are a few sellers up there with completely ridiculous asking prices and what amount to permanent auctions on these. This tends to mislead the usual eBay surplus scavengers into thinking that's what they can get for the partially functional or physically damaged units that they bought for next to nothing. But if you watch, you can still occasionally find one at a reasonable price, or maybe even talk a seller down by showing him what they actual sell for. The last one I bought I paid $75 (shipped). This is all eBay US, so maybe the situation is different where you are.

There are other good, but inexpensive, supplies out there, I am sure. This might be a good topic for a separate thread on the forum. Another option, if you want a project, is to get one of these old supplies and scrap everything except the chassis, KV divider, and transformer. Building a very good quality series regulator is not very complicated with all the wonderful ICs out there now.

If you ever decide to give that supply away I will sign up. I have been wanting to get a Power Designs supply for awhile, and my current bench supply is really starting to act up. Oh and Im also a relative beginner. I just like high quality gear that you can actually repair (My background is in technician work).

Those HP supplies look beautiful. Remind me of this one...
http://www.ebay.com/itm/272157564667?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/272157564667?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
What are some general usages of a supply with so much precision? Maybe setting bias currents on transistor pairs? Most of the opamp circuitry I have worked with hasnt been too fussy (yet atleast  >:D)

There's rarely a need for that much precision in a voltage supply. I do also have a precision current source, and I've used that to characterize transistors and LEDs. It's just more controllable to set current directly rather than trying to hit a target current with a voltage source. A hundredth of a volt on a PN junction actually makes a significant difference in current.

What I like about the supplies is that they are very low noise, pure linear supplies - not even a switching pre-regulator to introduce switching noise. They do not have a fan, so silent operation. The schematic is available, and there is a "Theory of Operation" section in the manual that is a good way to learn more about the design of series voltage regulators. And they seem to last forever if you take care of them. Plus, there's just something about restoring one of these things to near original condition that is satisfying. So much of what is manufactured these days has a shelf life of at most a few years. It's just wonderful to see a piece of solid engineering like this, even if the tech is a little dated, and to bring it back to life and think about it maybe making some future engineer happy long after I am gone.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 21, 2016, 05:36:33 am
A beginner's question: do PD models that do not have dedicated CC/CV signalling bulb have any means to notify the user when control is switched to CC?

It depends on the model (and PD made quite a variety). My 2010 precision supply has no CC indicator. Some of my non-precision ones (e.g., 6050A, TP340A) have a fault light that comes on or flashes when the current limiter is triggered. The 6050C and D have an actual CV/CC mode indicator.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 21, 2016, 05:47:36 am
If you're OK with voltage adjustment via a potentiometer, there are lots of the older HP supplies like the 6237B on eBay for very cheap.

+1

My first bench supply was an HP 6200B. Dual range. Plenty of power. Passively cooled. Compact. And a nice big toggle for a power switch.

To add a digital readout to a vintage analog power supply, connect a free cheapie multimeter from Harbor Freight. :-DMM

Quote
IMHO the nicest "vintage" supplies are the HP 6114A and 6115A. I've repaired and completely refurbished several of these, and I love them and will never part with them :) They are really scarce now...

Yeah, I've been looking for a 6114A with 10-turn pot at a reasonable price for, I don't know, a year now? Like you said, the flippers on eBay want way too much for them. $300+ :o

What do you find to be the primary pros/cons of the HP 6114A/6115A vs the PD 2005/2010/2020/4010/5020 precision supplies?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 21, 2016, 06:11:17 am
Quote
To add a digital readout to a vintage analog power supply, connect a free cheapie multimeter from Harbor Freight. :-DMM

Yes, or you can buy these little voltmeter's off of eBay for ~$3. They have 3 7-segment LEDs, and read up to 30V or so, with precision in tenths of a volt.


Quote
Yeah, I've been looking for a 6114A with 10-turn pot at a reasonable price for, I don't know, a year now? Like you said, the flippers on eBay want way too much for them. $300+ :o

You have to watch. Honestly, those guys flipping them are insane, and I wish they'd just take the auction down. There is one guy who is asking $750 for one! But don't be discouraged if the PS does not have the ten-turn pot. It is extremely simple to replace the existing pot with a 10-turn model. Here are links to the parts on DigiKey:

Turns counter: https://www.digikey.com/product-detail/en/kilo-international/411/411KL-ND/52230 (https://www.digikey.com/product-detail/en/kilo-international/411/411KL-ND/52230)
10-turn 1K potentiometer (Bournes): https://www.digikey.com/product-detail/en/kilo-international/411/411KL-ND/52230 (https://www.digikey.com/product-detail/en/kilo-international/411/411KL-ND/52230)
There is also a Vishay model that is less expensive but which fits. I can't find the part on that at the moment.

Quote
What do you find to be the primary pros/cons of the HP 6114A/6115A vs the PD 2005/2010/2020/4010/5020 precision supplies?



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 21, 2016, 06:43:44 am
Ah, yes. Those little DVM modules are cool. They get up to 5 digits for a few bucks more.

Thanks for the links. I'll probably end up going the DIY upgrade route, depending on how my patience lasts. ;D

Nice comparison. #1 HP push wheels worry me a bit, too. The PD knobs look cool and unusual. #2 is the reason I waited to buy a 2010, no custom oven. #3 & 4 are the primary reasons I'd like to get one of the HP's. #5 I suppose could be a DIY upgrade to the PD. #6 for the PD is especially nice with panels that have engraved labels.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 21, 2016, 07:34:12 am
Ah, yes. Those little DVM modules are cool. They get up to 5 digits for a few bucks more.

Thanks for the links. I'll probably end up going the DIY upgrade route, depending on how my patience lasts. ;D

Nice comparison. #1 HP push wheels worry me a bit, too. The PD knobs look cool and unusual. #2 is the reason I waited to buy a 2010, no custom oven. #3 & 4 are the primary reasons I'd like to get one of the HP's. #5 I suppose could be a DIY upgrade to the PD. #6 for the PD is especially nice with panels that have engraved labels.

On the pushwheels: I have disassembled and cleaned two sets of them. It's not bad if you are careful. robrenz has some good tips on this in the topic he posted about his 611xA rebuild.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: iampoor on March 21, 2016, 08:07:41 am

There's rarely a need for that much precision in a voltage supply. I do also have a precision current source, and I've used that to characterize transistors and LEDs. It's just more controllable to set current directly rather than trying to hit a target current with a voltage source. A hundredth of a volt on a PN junction actually makes a significant difference in current.

What I like about the supplies is that they are very low noise, pure linear supplies - not even a switching pre-regulator to introduce switching noise. They do not have a fan, so silent operation. The schematic is available, and there is a "Theory of Operation" section in the manual that is a good way to learn more about the design of series voltage regulators. And they seem to last forever if you take care of them. Plus, there's just something about restoring one of these things to near original condition that is satisfying. So much of what is manufactured these days has a shelf life of at most a few years. It's just wonderful to see a piece of solid engineering like this, even if the tech is a little dated, and to bring it back to life and think about it maybe making some future engineer happy long after I am gone.

That make sense. Can you use any of the PD supplies in a constant current mode?

I am a big fan of linear supplies too. I do audio work, so ultra clean power supplies are very important. Not to mention they are beautiful.  8)
I am hoping to find something local or super cheap. Seems like restoring one would be fun! Plus my current supply is starting to freak out. Bad caps, switches, an a regulator that is a few volt out of spec until it heats up. No bueno!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on March 21, 2016, 08:43:22 am

Ah, yes. Those little DVM modules are cool. They get up to 5 digits for a few bucks more.

Thanks for the links. I'll probably end up going the DIY upgrade route, depending on how my patience lasts. ;D

Nice comparison. #1 HP push wheels worry me a bit, too. The PD knobs look cool and unusual. #2 is the reason I waited to buy a 2010, no custom oven. #3 & 4 are the primary reasons I'd like to get one of the HP's. #5 I suppose could be a DIY upgrade to the PD. #6 for the PD is especially nice with panels that have engraved labels.

On the pushwheels: I have disassembled and cleaned two sets of them. It's not bad if you are careful. robrenz has some good tips on this in the topic he posted about his 611xA rebuild.

I've refurbished two myself and the first one went just fine. On the second one the paint started coming off the wheels!

So I had the idea of buying a similar set of push wheel switches from eBay, made by the same company and from the same era. The idea being I'd just take them apart and pull the wheels out. Well, that turned out to be a no-go. I assume HP had these custom made, because every other set of push-wheel switches seen by this company rotate the opposite direction from the ones in 611xA. (This means the numbers are in the wrong order.)

So, what I did instead was used my digital cutting machine to cut new numbers out of white adhesive vinyl. Kind of a pain in the ass to get them all aligned right, but it looks nice. Next time, I think I might try cutting all the numbers into a strip of static cling vinyl instead and then wrapping it around to wheel and applying white spray pain. Let it dry, remove the cling stencil and voilà!

Anyway. Very nice power supplies. Also, I made up some custom adapter boards to replace those 4-Terminal Sprague caps with standard 10mm Snap Caps. They're up on OSHPark if anyone wants them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on March 21, 2016, 02:46:52 pm
Can you use any of the PD supplies in a constant current mode?
That will depend on the model.

I'd look at the front panel photos on eBay for a CV/CC selector switch as not all of their models have this. For example, my TP343B is strictly a CV unit with current limiting, while the 5005R has a CV/CC selector switch ring on the fine adjust pot.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 21, 2016, 03:26:33 pm
So, what I did instead was used my digital cutting machine to cut new numbers out of white adhesive vinyl. Kind of a pain in the ass to get them all aligned right, but it looks nice. Next time, I think I might try cutting all the numbers into a strip of static cling vinyl instead and then wrapping it around to wheel and applying white spray pain. Let it dry, remove the cling stencil and voilà!

This is a great idea. The paint powdering on those wheels is about the only risk to disassembling them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 21, 2016, 03:29:39 pm
Anyway. Very nice power supplies. Also, I made up some custom adapter boards to replace those 4-Terminal Sprague caps with standard 10mm Snap Caps. They're up on OSHPark if anyone wants them.

BTW - can you give a link to the OSHPark project? I searched for it, but wasn't able to find it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on March 22, 2016, 09:20:22 pm

Anyway. Very nice power supplies. Also, I made up some custom adapter boards to replace those 4-Terminal Sprague caps with standard 10mm Snap Caps. They're up on OSHPark if anyone wants them.

BTW - can you give a link to the OSHPark project? I searched for it, but wasn't able to find it.

Yes, I actually need to upload new Gerbers first. One of the pads was off by 0.5mm (they still worked fine, but I might as well fix it). I'll do that tonight and pop the link here).

I also bought a physical copy of the 6114A service manual and scanned it plus the schematics in at 600DPI. I spent 12 hours stitching the schematics together, cleaning it up, and adding stuff from the Eratta sheet. I'll upload that, too. :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 22, 2016, 09:45:22 pm

Anyway. Very nice power supplies. Also, I made up some custom adapter boards to replace those 4-Terminal Sprague caps with standard 10mm Snap Caps. They're up on OSHPark if anyone wants them.

BTW - can you give a link to the OSHPark project? I searched for it, but wasn't able to find it.

Yes, I actually need to upload new Gerbers first. One of the pads was off by 0.5mm (they still worked fine, but I might as well fix it). I'll do that tonight and pop the link here).

I also bought a physical copy of the 6114A service manual and scanned it plus the schematics in at 600DPI. I spent 12 hours stitching the schematics together, cleaning it up, and adding stuff from the Eratta sheet. I'll upload that, too. :)

Oh, that's great. I am sure a lot of people will appreciate an improved scans. I was able to get a very good copy of the HP 6117C manual from Artek Manuals, but I obviously can't share that. I see they have a 611xA scan, for $12.50, but since I have a printed manual for that I didn't bother with it. As you've noticed, the existing free scans of the 611xA manual are not very good quality. The Artek Manual scans I have seen are excellent, but they are obviously not free.

http://artekmanuals.com/ (http://artekmanuals.com/)

Will you please post back when you update OSHPark? Also, I would be interested if you have a part number for the caps you used. This is one of the few aspects of these supplies that I haven't refurbished, for exactly the reason you created those adapter boards.

Also, if anyone needs parts for a 611xA. I have a totalled 6114A that I scrapped for parts long ago. I've pulled a number of things from it, but there's still some good stuff there. Let me know if there is a particular part you need, and I will check if I have it.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: PaulAm on March 23, 2016, 02:47:13 pm
I got one of the 6114As a while ago for $60 and the only problem was the paint flaking off the tens digit.  Taking it apart wasn't too bad, and I made a tool to shave off the heat welded divots of the plastic pegs.  Since it was only the one wheel, I was able to paint the numbers back with UV cured paint.  Not perfect, but it turned out more than adequate..

Those are really nice supplies.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 23, 2016, 04:32:00 pm
I got one of the 6114As a while ago for $60 and the only problem was the paint flaking off the tens digit.  Taking it apart wasn't too bad, and I made a tool to shave off the heat welded divots of the plastic pegs.  Since it was only the one wheel, I was able to paint the numbers back with UV cured paint.  Not perfect, but it turned out more than adequate..

Those are really nice supplies.

I've got one here with missing paint on the zero of the hundredths digit. Beyond my skill to repaint it though - I'd just end up with more damaged digits. I like timb's idea of a vinyl stencil and spray paint.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on March 23, 2016, 11:21:27 pm

I got one of the 6114As a while ago for $60 and the only problem was the paint flaking off the tens digit.  Taking it apart wasn't too bad, and I made a tool to shave off the heat welded divots of the plastic pegs.  Since it was only the one wheel, I was able to paint the numbers back with UV cured paint.  Not perfect, but it turned out more than adequate..

Those are really nice supplies.

I've got one here with missing paint on the zero of the hundredths digit. Beyond my skill to repaint it though - I'd just end up with more damaged digits. I like timb's idea of a vinyl stencil and spray paint.

I can make up some vinyl stencils for you if you want to give it a go. I've actually got another 6114A here with damaged digits, so maybe I'll give it a go too. (This unit was in pretty bad shape. I need to locate a few parts before I can get it back together. Namely the mV pot and a front panel overlay in decent shape.)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 24, 2016, 03:11:13 am

I got one of the 6114As a while ago for $60 and the only problem was the paint flaking off the tens digit.  Taking it apart wasn't too bad, and I made a tool to shave off the heat welded divots of the plastic pegs.  Since it was only the one wheel, I was able to paint the numbers back with UV cured paint.  Not perfect, but it turned out more than adequate..

Those are really nice supplies.

I've got one here with missing paint on the zero of the hundredths digit. Beyond my skill to repaint it though - I'd just end up with more damaged digits. I like timb's idea of a vinyl stencil and spray paint.

I can make up some vinyl stencils for you if you want to give it a go. I've actually got another 6114A here with damaged digits, so maybe I'll give it a go too. (This unit was in pretty bad shape. I need to locate a few parts before I can get it back together. Namely the mV pot and a front panel overlay in decent shape.)

Sure. I have a couple of spare wheels I can experiment on without risk. Please let me know what you need.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: iampoor on March 24, 2016, 03:57:40 am
Can you use any of the PD supplies in a constant current mode?
That will depend on the model.

I'd look at the front panel photos on eBay for a CV/CC selector switch as not all of their models have this. For example, my TP343B is strictly a CV unit with current limiting, while the 5005R has a CV/CC selector switch ring on the fine adjust pot.

Thanks! Maybe that will be one more reason to justify buying one. I dont have any supplies that can do CC in my lab.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 24, 2016, 09:44:44 pm
Uh oh. Looks like we've ended up hijacking the PD thread into HP land. Before we get more good info in here, perhaps we should relocate and link to the timb/Pedro/motocoder 6114A restoration thread or start a new one for the 611x series.

(And then eBay prices will go up even more :-DD)

Adding links to the two big 6114A threads:

PedroDaGr8 https://www.eevblog.com/forum/testgear/hp-6114a-precision-power-supply/ (https://www.eevblog.com/forum/testgear/hp-6114a-precision-power-supply/)
robrenz https://www.eevblog.com/forum/testgear/hp-6114a-precision-power-supply-restoration/ (https://www.eevblog.com/forum/testgear/hp-6114a-precision-power-supply-restoration/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on March 28, 2016, 05:05:26 pm
Pretty good price for a decent looking 5020 just listed on ebay (http://www.ebay.com/itm/Power-Designs-Inc-PDI-MODEL-5020-0-20V-2A-0-50V-1A-Precision-DC-Power-Supply-/131765025859?).  Too bad I can't justify another one of these excellent supplies.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on March 28, 2016, 06:05:54 pm
Pretty good price for a decent looking 5020 just listed on ebay (http://www.ebay.com/itm/Power-Designs-Inc-PDI-MODEL-5020-0-20V-2A-0-50V-1A-Precision-DC-Power-Supply-/131765025859?).  Too bad I can't justify another one of these excellent supplies.

That does look pretty good, although that permanent marker on the front bezel might be hard to remove...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 28, 2016, 07:39:40 pm
Tempting. The permanent marker could be tricky since the aluminum panel has a clearcoat on it. However, I find the applique on the left two voltage dials more annoying. This is one of those hybrid assemblies that have the stickered knobs on one side and the engraved or silkscreened ones on the other. It could also be that the silkscreen labels wore off and someone stuck their own on top.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on March 29, 2016, 05:36:54 am
Sweet! Thanks for the heads up.  Just got it :-+

BTW, there are a couple 3K10B (3kV/10mA) supplies available at eBay auction: #252330600672.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 29, 2016, 06:18:34 am
Congrats, pelud. We look forward to hearing and seeing all about it when it arrives. :-/O
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on March 29, 2016, 02:18:42 pm
Thanks for the headsup on the 3K10B, rarer to find for sale, still used in many labs.  Got it.  If I've time I'll tear it down with photos for all as there is little on in on the net.

Sweet! Thanks for the heads up.  Just got it :-+

BTW, there are a couple 3K10B (3kV/10mA) supplies available at eBay auction: #252330600672.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on March 29, 2016, 04:22:59 pm
I made sure to get one before I posted on here ;)  It didn't take long for these to sell!

Thanks for the headsup on the 3K10B, rarer to find for sale, still used in many labs.  Got it.  If I've time I'll tear it down with photos for all as there is little on in on the net.

Sweet! Thanks for the heads up.  Just got it :-+

BTW, there are a couple 3K10B (3kV/10mA) supplies available at eBay auction: #252330600672.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on March 29, 2016, 09:17:46 pm
Thanks pelud.  When I browsed for a kV PD design [ for some years! I might add] I always saw the "HV" models, which tended to be bulky and expensive.  I never knew about this series, or at least missed the rare posts on eevblog about it.  Seeing your post, it was a dream come true.  There is another on eBay that is 'as is' for $60 plus shipping, others are at ~$200.  FWIW new it was $700 in the mid-1990s. 

Currently I use an electrophoresis supply to generate up to 3kV but its a noisy SMPS.

I made sure to get one before I posted on here ;)  It didn't take long for these to sell!

Thanks for the headsup on the 3K10B, rarer to find for sale, still used in many labs.  Got it.  If I've time I'll tear it down with photos for all as there is little on in on the net.

Sweet! Thanks for the heads up.  Just got it :-+

BTW, there are a couple 3K10B (3kV/10mA) supplies available at eBay auction: #252330600672.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on March 30, 2016, 03:07:28 am
Those 2k10b's look nice!

Coincidently, over the past few months I've picked up a couple of old school Power Designs high voltage supplies. They were both cheap ebay deals and I couldn't help myself. ::). They both need some cleaning up but seem to work perfectly. My first test equipment with tubes!

I found a manual for the 2k10 online but no luck finding a manual for the HV-1547. Any lead on a manual for that one much apreciated.  I've already checked the usual sources.

I still need to make up some cables for the funky hv output connectors.

What I'll do with these guys i have no idea yet. I'm sure I'll think of something. Ideas welcome!

.(https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=213070)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 31, 2016, 12:48:19 am
I've seen some of those HV supplies go by, but I don't have a (known) use for them. I'll be interested to hear what you all do with them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on March 31, 2016, 06:30:42 pm
I commonly use it for dielectric test or test rated maximum working voltage, to part's failure.

A big problem today is counterfeit or substandard parts, or parts that are quite old.  While the parts we get from the proper supply chains [ e.g. Digikey] can unlikely be counterfeit, for my personal use I get surplus or whatever from eBay or worse.  A simple way to test its not likely counterfeit is if it lives up to its spec sheet, or a test that hinges on quality materials and manufacture, the dielectric withstand test.

If not a PD supply, you can get a Hi Pot or Insulation tester on eBay for about the same price, best capable of up to 3-5kV.   

Industrial HiPot testers tend to be heavily ab/used in life and when sold on eBay, and may not have much life left. 

$<200 new insulation testers from China are a good low cost substitute but they are commonly not continuously variable.

In general, brand name lab supplies of any type OTAH tend to be taken care off so they are better buys.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on March 31, 2016, 09:06:30 pm
I'll be interested to hear what you all do with them.

What I wonder is can these be turned on via an AC switch to full voltage?  If so maybe a remote critter killer can be made.  I am trying to catch a mouse that has evaded 15 traps so far.  I have a remote camera set up and I watch him check out every trap and it goes as far as the last step..
I bought every trap Home Depot sells except glue traps (just cannot go that far)

I have tried live traps first, then electric traps, then spring traps.

I wonder if I could rig something up and hit a remote switch that would turn on the unit.  I could place all the gadgets away and use wires and plates.  The main thing it would have to come on fast at the highest voltage, no ramping up.

Wonder if anyone has done this? 

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on March 31, 2016, 09:49:36 pm
Victor traps seem to have the market premade in e- traps:

http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C (http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C)

http://www.amazon.com/dp/B000E1RIUU (http://www.amazon.com/dp/B000E1RIUU)

Links have photos.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on April 01, 2016, 12:44:06 am
Victor traps seem to have the market premade in e- traps:

http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C (http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C)

http://www.amazon.com/dp/B000E1RIUU (http://www.amazon.com/dp/B000E1RIUU)

Links have photos.

I have 2 Victor electronic mouse traps (I do not have rats).  They take the food all the to the last plate.  He (or they) wil not take the last step in order to make contact from the last plate  :-[

I guess from an ozone smell from the charged plates.



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on April 01, 2016, 03:47:53 am
Victor traps seem to have the market premade in e- traps:

http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C (http://www.amazon.com/Victor-Electronic-Rat-Trap-M240/dp/B000LNX06C)

http://www.amazon.com/dp/B000E1RIUU (http://www.amazon.com/dp/B000E1RIUU)

Links have photos.

I have 2 Victor electronic mouse traps (I do not have rats).  They take the food all the to the last plate.  He (or they) wil not take the last step in order to make contact from the last plate  :-[

I guess from an ozone smell from the charged plates.

Maybe enable the voltage with some sort of proximity sensor then.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on April 01, 2016, 05:05:48 pm
I guess you have to mod it, some of the Amazon reviews talk about your problem.  Some have enlarged the plates, or put a wet towel to insure the mice's feet were conductive.

To prevent the bait from being removed and not tripping the trap I wrap a piece of meat with one entire spool of cotton thread.  The meat is underneath layers of thread.  The thread soaked into the meat, so they could smell and maybe sample it, but had to dig and struggle into the thread to try to reach the meat, always triggering the trap.  I could use a trap repeatedly made this way for 2 weeks or more and caught many mice with one bait.  After repeated use the thread would be torn up eventually and thus need redoing.


I have 2 Victor electronic mouse traps (I do not have rats).  They take the food all the to the last plate.  He (or they) wil not take the last step in order to make contact from the last plate  :-[
I guess from an ozone smell from the charged plates.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 02, 2016, 12:29:34 am
I commonly use it for dielectric test or test rated maximum working voltage, to part's failure.

A big problem today is counterfeit or substandard parts, or parts that are quite old.

Ah, OK. That is good to do when sourcing parts from who-knows-where.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on April 18, 2016, 01:33:42 am
I got the Power Designs 5020 Last Week. Here is a mini teardown:

(https://farm2.staticflickr.com/1476/26220699300_a08abf8eb9_z.jpg) (https://flic.kr/p/FX2Woq)
(https://farm2.staticflickr.com/1582/26493530675_495d1800bd_z.jpg) (https://flic.kr/p/Gn9gDD)
(https://farm2.staticflickr.com/1702/26467601346_d81a5be758_z.jpg) (https://flic.kr/p/GjRnLf)
(https://farm2.staticflickr.com/1453/26467603946_fd8b4a2f2c_z.jpg) (https://flic.kr/p/GjRox5)
(https://farm2.staticflickr.com/1489/26493533345_77bfbdf446_z.jpg) (https://flic.kr/p/Gn9hrF)
(https://farm2.staticflickr.com/1478/26493541675_0fcaaeeba9_z.jpg) (https://flic.kr/p/Gn9jVi)
(https://farm2.staticflickr.com/1682/26493540425_96a6b7ecf7_z.jpg) (https://flic.kr/p/Gn9jxK)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on April 18, 2016, 02:12:38 am
I got the Power Designs 5020 Last Week. Here is a mini teardown.

Turn it over, then tear it down.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 18, 2016, 04:55:41 am
Not bad. Needs some general cleaning, as usual. Looking forward to seeing the other side of the main PCB.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on April 18, 2016, 05:06:25 pm
OK, here's the bottom side of the 5020, including the LM399 reference:

(https://farm2.staticflickr.com/1528/26414621522_85eaf034e1_z.jpg) (https://flic.kr/p/GfaQH1)(https://farm2.staticflickr.com/1628/25902032514_cec2bd1453_z.jpg) (https://flic.kr/p/FsSFRu)
(https://farm2.staticflickr.com/1696/26414617892_4aa8e23bcb_z.jpg) (https://flic.kr/p/GfaPCq)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 18, 2016, 05:17:48 pm
Cool. That supply should clean up nicely. For the permanent marker on the front panel, give a melamine sponge (a.k.a., Magic Eraser) a try. Since the aluminum panel has a clear coat on it, you might want to test it a bit in the corner or somewhere less conspicuous to verify that it isn't too abrasive. If it does dull the clear coat, you can probably bring it back with an auto clear coat polish.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: PedroDaGr8 on April 18, 2016, 05:20:24 pm
Cool. That supply should clean up nicely. For the permanent marker on the front panel, give a melamine sponge (a.k.a., Magic Eraser) a try. Since the aluminum panel has a clear coat on it, you might want to test it a bit in the corner or somewhere less conspicuous to verify that it isn't too abrasive. If it does dull the clear coat, you can probably bring it back with an auto clear coat polish.

Before using an abrasive I would just use methanol (wood alcohol). It usually does a great job of removing sharpie, though if left on certain materials for too long the sharpie can seep in and then your only solution is an abrasive. Plus most (but not all) clear coat finishes are stable in methanol.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 18, 2016, 05:22:50 pm
Ah. Thanks for the tip, Pedro!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on April 18, 2016, 05:36:17 pm
Cool. That supply should clean up nicely. For the permanent marker on the front panel, give a melamine sponge (a.k.a., Magic Eraser) a try. Since the aluminum panel has a clear coat on it, you might want to test it a bit in the corner or somewhere less conspicuous to verify that it isn't too abrasive. If it does dull the clear coat, you can probably bring it back with an auto clear coat polish.

Before using an abrasive I would just use methanol (wood alcohol). It usually does a great job of removing sharpie, though if left on certain materials for too long the sharpie can seep in and then your only solution is an abrasive. Plus most (but not all) clear coat finishes are stable in methanol.
Pedro, I always had the impression methanol's vapors were a neurotoxic substance. However, given you are the chemist, perhaps my fears are unwarranted...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: PedroDaGr8 on April 18, 2016, 05:52:37 pm
Cool. That supply should clean up nicely. For the permanent marker on the front panel, give a melamine sponge (a.k.a., Magic Eraser) a try. Since the aluminum panel has a clear coat on it, you might want to test it a bit in the corner or somewhere less conspicuous to verify that it isn't too abrasive. If it does dull the clear coat, you can probably bring it back with an auto clear coat polish.

Before using an abrasive I would just use methanol (wood alcohol). It usually does a great job of removing sharpie, though if left on certain materials for too long the sharpie can seep in and then your only solution is an abrasive. Plus most (but not all) clear coat finishes are stable in methanol.
Pedro, I always had the impression methanol's vapors were a neurotoxic substance. However, given you are the chemist, perhaps my fears are unwarranted...
methanol isn't that bad from a vapor standpoint. In general as far a toxic substances go, it's pretty benign. Your body naturally produces methanol as a by product of certain chemical reactions, similarly you actually ingest methanol when you eat fruits and veggies. As a result your body has ways of removing it and dealing with it. The NIOSH limits are in the hundreds of mg/m3, making this a relatively benign material. For sure, it, like any toxic substance, should be used in a will ventilated area but it's not something to be afraid of. Usually, I apply it to a paper towel or squirt it with a squirt bottle. For us chemists, we usually keep three squirt bottles on hand. Chloroform, methanol or acetone, and toluene. The methanol bottle is most commonly used for removing permament marker.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on April 18, 2016, 09:15:40 pm
Wow, thanks a bunch Pedro. A few weeks ago I had to remove some permanent ink from the top cover of a Keithley 191 and I really wish I knew that - perhaps it would have saved me to waste a lot of "elbow grease". Although Isopropyl alcohol was not terribly bad, as it loosened the ink enough so I could scratch it out somewhat easily with a sewing needle (needed to get into those crevices of the ABS plastic cover)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on April 18, 2016, 09:24:13 pm
Is it just me, or does R74 look toasty.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 18, 2016, 09:26:54 pm
It's not just you. It seemed a bit crispy on the outside to me, too. It's also interesting that they drilled out the circuit board below the smaller wire-wound resistors. It'd be interesting to get some temps after the supply has been running under load for a while.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 21, 2016, 12:19:31 am
Here's one I haven't seen before: Model 605 0-6VDC, 0-500mA. Looks like it has their custom oven like the 2005 models. The rear panel is like Swiss cheese.

Someone buy it so it stops tempting me. :-DD

http://www.ebay.com/itm/291742748367 (http://www.ebay.com/itm/291742748367)

Front:
(http://i.ebayimg.com/images/g/kB0AAOSwiYFXFptY/s-l1600.jpg)

Top:
(http://i.ebayimg.com/images/g/kKQAAOSw3mpXFpth/s-l1600.jpg)

Rear:
(http://i.ebayimg.com/images/g/yKIAAOSw1DtXFpuH/s-l1600.jpg)

(http://i.ebayimg.com/images/g/l9oAAOSwD2pXFptr/s-l1600.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on April 21, 2016, 12:45:44 am
Here's one I haven't seen before: Model 605 0-6VDC, 0-500mA. Looks like it has their custom oven like the 2005 models. The rear panel is like Swiss cheese.

Someone buy it so it stops tempting me. :-DD

http://www.ebay.com/itm/291742748367 (http://www.ebay.com/itm/291742748367).


Very cool! I've never seen this model before
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 23, 2016, 02:12:49 am
Looks like someone bought it. Anyone here?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on April 24, 2016, 09:33:22 pm
Looks like someone bought it. Anyone here?

It was me. I've been trying to work with only a single power supply and I've gotten tired of having to include so many regulator ICs even for simple circuits. It'll be nice to have a proper second supply. Especially one that's so much more precise than my current one.

I hope I didn't steal it out from under your nose, but you did say that you wanted someone to buy it.  ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 25, 2016, 12:09:38 am
Hi Ampere! Congrats on joining the PD Precision club. I'm glad someone here got it. Yes, you saved me since your offer was higher. :-+

I've never seen the 605 before, so hopefully you'll post teardown photos of it when you get it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on May 01, 2016, 02:19:00 am
My Model 605 arrived in the mail today. I turned it on instead of taking it apart right away (big mistake) and found that it was off by over 50mV on nearly every setting.  Even 0V! :-BROKE

Then I did a cursory teardown (Link (http://imgur.com/a/LayMd)) and I think it's pretty obvious what's wrong. Most of the large electrolytics have completely failed so of course it's not going to operate within spec.

I don't have anything like the 100uF 80V on hand except for two salvaged "Jay'Long" 680uF 200V caps, but I wouldn't dare put these monstrosities in what is otherwise quite a nice design. I'll just order some. Serves me right for not keeping enough caps on hand.  :palm:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on May 01, 2016, 02:32:00 am
I don't have anything like the 100uF 80V on hand except for two salvaged "Jay'Long" 680uF 200V caps, but I wouldn't dare put these monstrosities in what is otherwise quite a nice design. I'll just order some. Serves me right for not keeping enough caps on hand.  :palm:
Meh. It helps keep your rarely used parts inventory under control, which is a good thing IMHO.   ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 01, 2016, 05:30:07 am
Cool little supply. Thanks for the teardown photos. Big cans. Some crusty caps. A little dusty, but should be pretty nice once you've gone through it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on June 12, 2016, 08:10:09 pm
I finally got some time today to test out the Power Designs 5020.  Unfortunately, it doesn't work :'( 

The original seller stated that there was no output when he first attempted to test it, but then it started working. Quote from seller: "When I received this power supply, it powered on, but there was no output. Both the internal, and the rear mounted fuses checked out, and after I checked them, the power supply began working properly, as shown in the photos, so there may be a loose connection somewhere."

I should have known better to fire the thing up without checking the caps, etc, but I was getting too impatient to wait.  I heard a bit of a "frying" noise when first turning it on, although nothing smells or looks abnormal.  The voltage reading on the front panel meter never moved, but the output reads -46V on my DMM.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on June 12, 2016, 09:09:13 pm
Hi John,

Sorry to hear about the sizzling. If you look at the bottom board, the power resistor R74 already looked pretty crispy in your teardown photos. Check the rectifier diodes (C29 and up) and the filter caps (C32, C33). One or more might be shorted.

I don't have schematics handy for this supply, but those are my initial impressions. Looking forward to hear what you discover. I may get a 5020 one of these days.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on June 14, 2016, 12:05:03 am
Here's one I haven't seen before: Model 605 0-6VDC, 0-500mA. Looks like it has their custom oven like the 2005 models. The rear panel is like Swiss cheese.

Someone buy it so it stops tempting me. :-DD

http://www.ebay.com/itm/291742748367 (http://www.ebay.com/itm/291742748367)

Front:
(http://i.ebayimg.com/images/g/kB0AAOSwiYFXFptY/s-l1600.jpg)

Top:
(http://i.ebayimg.com/images/g/kKQAAOSw3mpXFpth/s-l1600.jpg)

Rear:
(http://i.ebayimg.com/images/g/yKIAAOSw1DtXFpuH/s-l1600.jpg)

(http://i.ebayimg.com/images/g/l9oAAOSwD2pXFptr/s-l1600.jpg)

Somehow I lost track of this thread, so I totally missed this! I picked one of these up on eBay about a year ago, but it's still sitting in a box awaiting restoration. Mine powers up, but the oven never goes off, so I think the thermostat is bad.

That's a very common problem with all these ovenized PD supplies and a big disadvantage to keeping the oven powered even when the supply is turned off: The thermostats use a bimetallic disc which wears out after a few hundred thousand cycles.

The thermostat module is actually soldered to the bottom of the oven's inner can (under the socket). It's of a size and shape that appears to no longer be made and I've been unable to locate a suitable replacement.

It's such a common problem, that I've actually designed a fairly simple, yet accurate oven controller as a replacement. It's 100% solid state and keeps the oven within 0.5C of the set point. Originally I intended to use a relay, but opted for a little Triac in a SOIC package instead (no sense replacing a mechanical switch with another mechanical switch).

I need to finish laying out the board, but once I do I'll have a batch made and do some final tests with my own supplies. If everything works out, I'll offer up retrofit kits if anyone is interested. It should be rather simple to swap over to my controller.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on June 14, 2016, 08:45:28 pm
That retrofit kit sounds great, Tim. I've avoided the older models because of that oven and ended up getting a 2010 instead.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on June 21, 2016, 05:44:06 am
Sorry for keeping you all waiting so long for an update. I powered on the 605 after switching out the caps (all but the very largest which seemed OK) and the supply still does not work. The voltages all wrong. When set to 0V, I'm reading -4.64mV. When set to 1V, I'm measuring 990.7mV. Etc. I don't think it is the temperature control problem mentioned above because the voltages do not appear to depend on whether the oven is currently on or off. Is it possible that the reference itself could have gone bad or drifted over time?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on June 21, 2016, 05:29:43 pm
It doesn't seem very far off: 9.3 mV out of 1 V is 0.9%. It could just need adjusting. However, blindly adjusting the output could mask problems. Check it at several more voltage levels throughout the entire range. See if it's off by a similar percentage. If it is, then it probably just needs adjusting. It is old, after all.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on June 22, 2016, 07:57:19 pm
I allowed more time for the voltage to settle and I'm getting the results shown below. They aren't the same results I was getting before for 0V and 100mV, but maybe it took a few heating cycles to really settle because the new results I got last night and the ones I'm getting now are very, very close.

Is it normal for the lower ranges to be off by so much more than the higher ones? If that's normal then I wouldn't mind giving it a tweak.  :-/O My best meter is only 0.1%(+2) accurate, but I'd be happy if I could get the supply close to that.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Vgkid on June 22, 2016, 09:29:35 pm
That is not unexpected, the lower ranges use less accurate voltage setting resistors.
Also: what is the accuracy of your meter below a volt.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: timb on June 22, 2016, 11:53:25 pm
Most likely the resistors have drifted over time. Above 1V the deviation seems consistent, so you should be able to calibrate it. I'll pull mine out tonight and figure out which pots you need to tweak.

The deviation below 1V is most likely your meter and not the unit. What kind of meter are you using?

Anyway, there's normally two pots you have to tweak, one for zero set and the other for cal. There may also be a pot to adjust the front panel meter.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Ampere on June 24, 2016, 04:34:12 am
That is not unexpected, the lower ranges use less accurate voltage setting resistors.
Also: what is the accuracy of your meter below a volt.

It's a UT61E. The 220mV range is accurate to 0.1%+5 (at 0.01mV resolution) and the 2.2V and 22V ranges are accurate to 0.1%+2 (at 0.0001V and 0.001V resolution, respectively).

Most likely the resistors have drifted over time. Above 1V the deviation seems consistent, so you should be able to calibrate it. I'll pull mine out tonight and figure out which pots you need to tweak.

The deviation below 1V is most likely your meter and not the unit. What kind of meter are you using?

Anyway, there's normally two pots you have to tweak, one for zero set and the other for cal. There may also be a pot to adjust the front panel meter.

Thanks. That would be a big help!  :)

My meter is a UT61E. I know it's not the best meter, but the specs lead me to believe that it's accurate enough that what I'm reading can't entirely be blamed on meter accuracy. I also checked the results against a second (much less reliable) meter as a sanity check and the results were quite similar.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on June 24, 2016, 05:34:11 am
That meter is fine for this and other low-power electronics. Plus it has a pretty high resolution, which is nice for monitoring small changes. The major issue is safety if you're using it on high-energy circuits with the standard fuses. Although I've heard of some drift over time, you have a voltage reference to check it against. So, you should be just fine.

Carry on.  :-/O :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 11, 2016, 03:06:36 am
Did a member happen to snag this 2005A today? It looked really clean (even had feet and tilting bail) and was very hard to resist rescuing it myself. $25 is quite the score and timb has parts for sale to finish restoring it.

http://www.ebay.com/itm/282122401045 (http://www.ebay.com/itm/282122401045)

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: pelud on September 02, 2016, 07:52:22 pm
Just a heads up: There's currently a 2020B listed on ebay for $75. eBay auction: #142105850722
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on January 23, 2017, 05:30:11 pm
In case anyone is interested, I have an HP 6115A that I am selling.

https://www.eevblog.com/forum/buysellwanted/fs-hp-6115a-precision-power-supply-(us-only)/ (https://www.eevblog.com/forum/buysellwanted/fs-hp-6115a-precision-power-supply-(us-only)/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on February 22, 2017, 07:31:32 am
OK fellow PD fans and TEA members. I just spotted a nice looking 2005A on the bay for $65 + $30 (US only- sorry). Link HERE (http://www.ebay.com/itm/332134323395?ul_ref=http%253A%252F%252Frover.ebay.com%252Frover%252F0%252Fe11021.m43.l3160%252F7%253Feuid%253D11d6395cc4734c56a263ef66f3211128%2526bu%253D43176726367%2526loc%253Dhttp%25253A%25252F%25252Fwww.ebay.com%25252Fulk%25252Fitm%25252F332134323395%2526sojTags%253Dbu%253Dbu%2526srcrot%253De11021.m43.l3160%2526rvr_id%253D0&ul_noapp=true).

 If i didn't have one already...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on February 22, 2017, 01:00:26 pm
I have a PD2005A I will give to anyone in the Seattle/Puget sound area that can come pick it up. I have repaired a broken heater thermostat on it with a small circuit of my own design, and converted the heater to run on the unused phase of the secondary transformer output (so I wasn't messing with mains). The supply works great, but it's just sitting on my shelf. I would rather someone get some use out of it. 

Please post here and PM me of you are interested. Again, only people who can pick it up locally to me. I live in Issaquah and work in Redmond, Washington.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 05, 2017, 02:41:58 am
Here's an interesting version of the 2020. All the 2010 and 2020 I've seen were in the horizontal enclosure.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 15, 2017, 10:33:53 pm
Can any PD fans here enlighten me on the difference between the 5015-S and 5015-T models. I know that the A model was much older than these and the R is the newest one with a digital display. I can only find a schematic/ manual for the T and not the S so I was windering what the differences are since the appear to be identical from the outside and from the specs.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 15, 2017, 10:57:21 pm
Hmm, I'm not really sure about those two variations in particular. Since the specs are the same, it may simply be architectural changes due to availability of parts or the like. Now that you've brought it up, I'd be curious to know more as well.

Unfortunately, there isn't a lot of info out there about the company or its products. I guess we, the PD product owners, need to start a wiki to consolidate whatever info we're able to find. I haven't even found documentation for all the supplies I already have.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 15, 2017, 11:48:22 pm
Hmm, I'm not really sure about those two variations in particular. Since the specs are the same, it may simply be architectural changes due to availability of parts or the like. Now that you've brought it up, I'd be curious to know more as well.

Unfortunately, there isn't a lot of info out there about the company or its products. I guess we, the PD product owners, need to start a wiki to consolidate whatever info we're able to find. I haven't even found documentation for all the supplies I already have.

I just noticed a difference. There is probably something different in the error amplifier as the regulation specs are slightly different. 0.01% vs 0.05%.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 15, 2017, 11:50:41 pm
Oh, OK. Which is which?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 12:14:14 am
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on August 16, 2017, 12:44:22 am
...  Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:

I know I am in the minority, but is it possible aliens made these?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 01:06:07 am
...  Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:

I know I am in the minority, but is it possible aliens made these?

I'm fairly certain of it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: motocoder on August 16, 2017, 01:24:18 am
Most of us moved on to the HP 611x supplies  :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 01:37:42 am
Most of us moved on to the HO 611x supplies  :-DD

ewwwww!  :P Well, the HP (I assume you are talking about HP) precision supplies do have a certain... oh how shall I put this?.... functional "charm" about them. They do, however, lack copious amounts of aluminum and appear to be bathed in plastics of some kind. Only a face a mother could love, I think.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 16, 2017, 04:45:31 am
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty.

Yeah, even a 2015R should be fine unless he's making stuff that need more than 20V.

Quote
No way he is touching my 2020B... no way.  ;D

LOL! It's hard to find a really nice 2020B. I have a 2010, thus far.

Quote
BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:

Not that I'm aware of. I could start a thread just for collecting and organizing PD info if folks are interested in building such a resource.

Most of us moved on to the HO 611x supplies  :-DD

ewwwww!  :P Well, the HP (I assume you are talking about HP) precision supplies do have a certain... oh how shall I put this?.... functional "charm" about them. They do, however, lack copious amounts of aluminum and appear to be bathed in plastics of some kind. Only a face a mother could love, I think.

Although the HPs don't have the Art Deco/Streamline Moderne aesthetic of the PDs, they do have a lot of aluminum inside. If you haven't seen inside a 611xA or other instruments that use the "System I" enclosure, the beauty is inside (aluminum skeleton and gold traces/contacts). Here's my HP 3469A multimeter (https://www.eevblog.com/forum/testgear/hp-3469a-multimeter-70's-vintage-teardown-and-clean-up/) for a sampling.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 02:43:00 pm
Although the HPs don't have the Art Deco/Streamline Moderne aesthetic of the PDs, they do have a lot of aluminum inside. If you haven't seen inside a 611xA or other instruments that use the "System I" enclosure, the beauty is inside (aluminum skeleton and gold traces/contacts). Here's my HP 3469A multimeter (https://www.eevblog.com/forum/testgear/hp-3469a-multimeter-70's-vintage-teardown-and-clean-up/) for a sampling.

Inside, for sure, but I usually don't stare at the internals unless there is an issue or after initial purchase for curiosity sake. When my 5335A Counter died, I parted it out and still have a stack of aluminum left (PM me for parts!). HP is all about the specs and durability which is all well and good but not so much visual appeal, especially for a collector. At any rate, finding a decent HP supply for under $50 is tough but PDs do drop under this price frequently.

I know this thread was about the Precision designs but I posted here because it appears to be the only PD thread in the forum with traction. Would be nice to have some sort of manufacturer-based resource on EEVblog, especially for the defunct ones.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on August 16, 2017, 02:51:24 pm
Would be nice to have some sort of manufacturer-based resource on EEVblog, especially for the defunct ones.
The entire company is defunct.  :o  :P

There's precious little information on this as well, so I'm uncertain we'll be able to put a real date to it IMHO. I suspect the best source of information we could hope for are former employees (aside from .pdf scans of manuals).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: saturation on August 16, 2017, 03:37:06 pm
Many forums have become the replacement 'manufacturer' support after they stop support even if they still exist.  K0BB and other volunteers maintain the service manuals etc.,  all are volunteers so its unlikely to be housed in a single location as they'll use whatever is easiest for them to use, support and work with.

As for PD, in this thread I think I traced the history some years ago, they were finally purchased by X and thereafter the name PD disappears, sometime early 2000.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: CatalinaWOW on August 16, 2017, 03:45:34 pm
Although the HPs don't have the Art Deco/Streamline Moderne aesthetic of the PDs, they do have a lot of aluminum inside. If you haven't seen inside a 611xA or other instruments that use the "System I" enclosure, the beauty is inside (aluminum skeleton and gold traces/contacts). Here's my HP 3469A multimeter (https://www.eevblog.com/forum/testgear/hp-3469a-multimeter-70's-vintage-teardown-and-clean-up/) for a sampling.

Inside, for sure, but I usually don't stare at the internals unless there is an issue or after initial purchase for curiosity sake. When my 5335A Counter died, I parted it out and still have a stack of aluminum left (PM me for parts!). HP is all about the specs and durability which is all well and good but not so much visual appeal, especially for a collector. At any rate, finding a decent HP supply for under $50 is tough but PDs do drop under this price frequently.

I know this thread was about the Precision designs but I posted here because it appears to be the only PD thread in the forum with traction. Would be nice to have some sort of manufacturer-based resource on EEVblog, especially for the defunct ones.

To each his own.  I just sold my 2005A, for $40 because I don't find it visually that appealing and that interface is just nasty to use.  The center knob isn't too bad, but the ring dial gets old in a real hurry when you are changing settings. 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 04:30:16 pm
To each his own.  I just sold my 2005A, for $40 because I don't find it visually that appealing and that interface is just nasty to use.  The center knob isn't too bad, but the ring dial gets old in a real hurry when you are changing settings.

Truth be told, I use my HP 6205C more often just for that reason but I look at my 2020B first when I step into the "lab" and its the one piece of equipment that draws the most comments (that and my stack of Keithley browns). Yes its a bit of a museum piece now but its still highly functional and a darn sight cheaper than any new cheap Chinese unit and more stable and accurate to boot. If I was doing precision voltages all day the HP would be a better bet but personally I would rather look at the PD.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on August 16, 2017, 05:03:58 pm
I just sold my 2005A, for $40 because I don't find it visually that appealing and that interface is just nasty to use.  The center knob isn't too bad, but the ring dial gets old in a real hurry when you are changing settings.

Whaaat?  Blasphemy!!   Who let this heathen into the church of the PD?   Cast thee out of  here demon, with thy digital PSU in hand... ;)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: CatalinaWOW on August 16, 2017, 08:51:29 pm
Not digital - I worship at the church of HP611x.

If it makes you feel better I have three other PD supplies that I am quite happy with.  Just think that PD got trapped in the technology limits and the attempt to be clever on the 2005A.  It works great, but is no fun to use.  Of course if you are not changing voltages frequently, particularly if you are not going back and forth over the decade boundary it is just fine.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on August 16, 2017, 09:43:08 pm
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on August 16, 2017, 10:30:40 pm
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Is the current delivery not flat up to 50V?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on August 16, 2017, 10:32:56 pm
Not digital - I worship at the church of HP622x.

That's ok.  I'm bi-denominational.  Currently with 4 PD supplies and 7 HP supplies including a 6114, 6115, 6632a and 6632b.  Shit - when I list them like that it makes me realize I have a PSU issue... :palm:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 17, 2017, 12:57:16 am
Inside, for sure, but I usually don't stare at the internals unless there is an issue or after initial purchase for curiosity sake. When my 5335A Counter died, I parted it out and still have a stack of aluminum left (PM me for parts!). HP is all about the specs and durability which is all well and good but not so much visual appeal, especially for a collector. At any rate, finding a decent HP supply for under $50 is tough but PDs do drop under this price frequently.

Yep, agreed. Unfortunately, most PD supplies don't support CC operation, just a crowbar. IIRC the only ones I've seen with CC are the precision ones and the newer digital display ones. Nevertheless, I've got a fair collection of them.

Quote
I know this thread was about the Precision designs but I posted here because it appears to be the only PD thread in the forum with traction.

It's OK. It's been wandering in and out of the precision models for a while.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 17, 2017, 01:02:35 am
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Yeah, most don't. The precision models (e.g., 2005, 2005A, 2010, 2020B, 5020) and the newer models with 7-segment displays (e.g., 6050C, TW347D, TW5005D) do.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on August 17, 2017, 01:12:13 am
That's ok.  I'm bi-denominational.  Currently with 4 PD supplies and 7 HP supplies including a 6114, 6115, 6632a and 6632b.  Shit - when I list them like that it makes me realize I have a PSU issue... :palm:

It's OK, mtdoc. GAS comes in many forms. Mine started with power supplies. :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on August 17, 2017, 01:38:54 am
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Is the current delivery not flat up to 50V?
Oh, no. I meant that the current control is a clamp. In other words, the output drops to zero if the limit is reached, requiring power cycling the power supply.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: don.r on September 02, 2017, 01:04:19 am
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Is the current delivery not flat up to 50V?
Oh, no. I meant that the current control is a clamp. In other words, the output drops to zero if the limit is reached, requiring power cycling the power supply.

Something must have changed between the A and the S because mine limits like a charm. Once the limit is reached the voltage starts dropping keeping current constant. Raise the limit and the voltage rises again. The only downside is that you need to set the limit with a dead short across the terminals.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on September 02, 2017, 03:45:41 am
T has better regulation than S. I'm shopping for my son's home lab (3rd year EE) and thought a little old school PSU would fit the bill. 50V @ 1.5A should be plenty. No way he is touching my 2020B... no way.  ;D

BTW, is there a Wiki on EEVblog? Seems to be almost no resources out there for PD collectors... which I guess I am now!  :scared:
I have a 5015A and its performance is absolutely amazing - I tested it throughout its range and the ripple was quite low and the voltage was quite stable. The only letdown for me is that it does not work as a current source.

Is the current delivery not flat up to 50V?
Oh, no. I meant that the current control is a clamp. In other words, the output drops to zero if the limit is reached, requiring power cycling the power supply.

Something must have changed between the A and the S because mine limits like a charm. Once the limit is reached the voltage starts dropping keeping current constant. Raise the limit and the voltage rises again. The only downside is that you need to set the limit with a dead short across the terminals.
FWIW, the images I see of the 5015A have a current knob (proper CC) rather than a set screw for current as is the case on other models (some with letters, some without).

(https://i.imgur.com/hGQ0WHq.jpg)


My TP343B is one that uses set screws for both current and over voltage (clamp & crowbar respectively). So if either OV or current trip, it has to be power cycled to reset it. Not a big deal, but I did pick up a GW Instek GPC-3020 for instances where I do need a proper CC capable PSU as I couldn't pass it up at just under $60 shipped (triple output, 2x @ 0 - 30V & 0 - 2A, and 1x fixed output @ 5V & 3A). >:D BTW, they're still available on eBay (here (http://www.ebay.com/itm/GW-Instek-GPC-3020-Dual-Tracking-with-5V-Fixed-DC-Power-Supply-Tested-Working-/122674914104?epid=1919387835&hash=item1c8ffea338:g:75gAAOSw6DtYXCdD)).

(https://i.imgur.com/rmKhrxj.jpg)

(https://i.imgur.com/RtlJUvs.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 06, 2017, 05:46:28 pm
Just finished working on two Power Designs power supplied that I purchased on Ebay.
The first one is a 6050D that was in fairly poor cosmetic shape, and missing some components.
It took quite a bit of work, but I am quite happy with the final results.
(https://www.barbouri.com/wp-content/uploads/2017/11/PD6050DfrontPanelOff02-768x440.jpg)

The second unit is a 6150 that mainly needed mechanical repairs and some cleaning.
I haven't seen many examples of this power supply, and still need some information for which potentiometers are used for calibrating the current meter.
(https://www.barbouri.com/wp-content/uploads/2017/11/PD6150-RepairFrontPanelOff01-768x147.jpg)

I documented the work on both power supplies with lots if hi-res photos on my blog pages.
https://www.barbouri.com/2017/11/29/power-designs-6050d-power-supply-repair/ (https://www.barbouri.com/2017/11/29/power-designs-6050d-power-supply-repair/) 6050D
https://www.barbouri.com/2017/11/30/power-designs-6150-universal-dc-power-source-restoration/ (https://www.barbouri.com/2017/11/30/power-designs-6150-universal-dc-power-source-restoration/) 6150

Barbouri
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 06, 2017, 07:59:52 pm
Welcome to the forum, Barbouri. Nice job on the 6050D. It looks great. I'll check out your blog for the details. I have a couple of 6050A, so I'm curious to see what the D is like inside.

Yeah, I see 6150 around on occasion, but they are rather rare. I've never worked on one.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 07, 2017, 01:16:36 am
Hi bitseeker,
Even though the 6050D in a more recent variant of the 6050 series, I was impressed with the quality of construction and engineering.
My only disappointment was the use of zip-ties for cable management, instead of waxed lacing cord.
I acquired a basket-case Power Designs 6050C on Ebay today. Should be interesting...

Thanks for the welcome,
Barbouri
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 07, 2017, 02:18:02 am
It's also interesting that the PCB on the 6050D, despite being much newer, looks like the same vintage as the 6050A.

Where did you get the replacement knobs for the 6050D? Those look pretty good. I'd still like to find three originals for my TP340A.

Looking forward to your 6050C repair.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on December 07, 2017, 02:22:23 am
Pretty nice work, Barbouri! Thank you for sharing.

I need to do some minimal TLC to my PD5015A as the ammeter is not working - everything else is in pristine condition and the noise/load is remarkable for a +/- 50 years old PS (mine has a General Dynamics calibration seal dated from 1969).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 07, 2017, 04:26:57 am
The knobs on the 6050D are from Digi-Key part #226-3148-ND and are  by Kilo International part#OESA-50-3-5

They do not sit as flush as the originals, but this unit came with only one knob. They are also not as tall as the originals, but in my opinion are a good match.

Unfortunately the recent 6050C has some shiny non-PD knobs on it, so will likely be getting the OESA-50-3-5 knobs for it too.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on December 08, 2017, 10:54:04 pm
I finally found the 5015A schematics (https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg1369898/#new).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 09, 2017, 02:24:15 am
Wow, nice find. Is that an original?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on December 09, 2017, 04:35:04 am
Yes, it certainly is. Quite remarkable the design is dated from 1961!  :o

FWIW, the images I see of the 5015A have a current knob (proper CC) rather than a set screw for current as is the case on other models (some with letters, some without).
The diagram I got had some usage instructions about the CC control of the 5015A, and they indicate it is a crowbar method, not CC. It also says there the price was $234.50 FOB factory in 1961 ($1919.81 in today's money), while the specified ripple is rated at less than 0.001% with a maximum of 500 microvolts  :o

That is engineering, my friends. Especially considering they used "silicon transistor amplifiers for maximum reliability" and "pre-aged germanium power transistors with controlled parameters to insure interchangeability and field reliability" while guaranteeing that "automatic Ico compensation circuit eliminates the possibility of turn-on and turn-off transients" and "fifty hour pre-aging of power supplies prior to test"

As someone else hinted in a past discussion, I am suspicious they were in fact from another planet and graced us with their designs...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 09, 2017, 05:35:22 am
Yeah, the noise on these supplies is outstanding.

It seems most of the PD supplies have current crowbars. I've only seen CC mode in the precision versions and the ones with digital displays.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: ez24 on December 09, 2017, 05:39:22 am
As someone else hinted in a past discussion, I am suspicious they were in fact from another planet and graced us with their designs...

Glad someone else believes this, since there is no internet history on them.  If something exists then it will be on the internet.  Since "they" do not exist but their products exist, something must be going on.  A logical explanation is aliens made them for some purpose that we do not know about.  Like help develop something for space flight that will take us to another planet.  Once this theory is proven then the value of these supplies will greatly increase.  I just hope humans will not become a food source like I think about every time I look at my power supply.  God forbid, the PD is not the alien (but just in case I use kind words when I talk to my power supply)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 09, 2017, 05:43:57 am
Well, one of my PD 6050A was owned by Grumman Aircraft. ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: texaspyro on December 09, 2017, 05:49:56 am
Well, one of my PD 6050A was owned by Grumman Aircraft. ;D

Meh,  mine were owned by Beldar Conehead from Remulac.  I traded him mass quantities of beer for them.   
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 09, 2017, 06:29:32 am
Show off! :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 23, 2017, 06:53:47 pm
Repairs are progressing on the Power Designs 6050C.

(https://www.barbouri.com/wp-content/uploads/2019/11/6050CcircuitBoardDamage02R.jpg)
PO did replace the leaking 22,000 uF 16V capacitor, but didn't bother to clean up the electrolyte that dripped down to the circuit board below.

(https://www.barbouri.com/wp-content/uploads/2019/11/6050CcircuitBoardCleaned01r.jpg)
Circuit board bottom after cleaning, repair, and replacing capacitors.
It is currently functional, but I need to do a full re-cap, and a few mechanical repairs before it is finished.

Also added to the bench is a Power Designs 2005A won on auction from Ebay for $26.00 plus shipping.
After an afternoon of cleaning and minor repairs. I still need to find a pair of rear feet for this unit.
I ended up using polarizing film instead of white paint for repairing the digital dial window.

(https://www.barbouri.com/wp-content/uploads/2017/12/2005A-CleanedFront1366.jpg)


Greg (Barbouri)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: hermit on December 23, 2017, 07:03:31 pm
God forbid, the PD is not the alien (but just in case I use kind words when I talk to my power supply)
Easily testable.  Hook it up to a scope and threaten it with a hammer.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 24, 2017, 12:05:27 am
Nice job with all the cleanups, Greg. That 2005A looks like new.

I still need to find a pair of rear feet for this unit.

Yeah, many of the PD supplies as well as some other brands of instruments from the same era (Systron Donner, etc.) used the same feet. I have a 6050A that's missing a rear one. If you find a source (other than buying whole devices just for their feet), let me know.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 24, 2017, 12:10:06 am
By the way, last night I saw a C400 on eBay (https://www.ebay.com/itm/Power-Designs-Model-C400-Precision-Power-Source-/173046769212) (100V, 400mA). They don't turn up very often. Looks like it sold at its BIN price of $135 plus shipping.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on January 17, 2018, 07:40:25 pm
Quote
Yeah, many of the PD supplies as well as some other brands of instruments from the same era (Systron Donner, etc.) used the same feet. I have a 6050A that's missing a rear one. If you find a source (other than buying whole devices just for their feet), let me know.
I did find a close match for the original rear feet on the 6050C. Just slightly shorter.
They are from Digikey Part# RPC1130-ND
Made by Essentra Components SFF-028, Foot Cylindrical, Tapered 0.787" Dia (20.00mm) Santoprene Black
I did end up cutting off the the expand attachment and used a 4-40 screw with the existing nuts.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on January 18, 2018, 12:05:56 am
Nice find. Thanks, Barbouri.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: sarel.wagner on February 09, 2018, 07:40:58 am
I have a 2005 early model and that used to be spot on. It recently lost its accuracy and zero volt set point, so something is amiss. the zero volts now show -320mv and the calibration is out by a set % up to about 300mv low on 20 volt. Time to trouble shoot. I managed to get the zero volts spot on again, but that was just checking if the offset can be changed. I did this by strapping the resistors differently, part of the calibration procedures. Have not yet started looking for the fault.
(https://i.imgur.com/JDFbxDx.png)
Since I need to fix this, also decided to clean it up as it was still as received.
-
This morning I managed to snag 2 A models from fleabay, one working and one not for $100.99 + shipping. The one on the left is claimed to be working. It seems a switch was changed on the other one. Happy chappy me  :-DD
(https://i.imgur.com/XeSJJFq.jpg)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on February 09, 2018, 07:51:45 am
Very nice. My 2010 also has the locking toggle switch for the voltage output range. It's a good safety feature.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on February 09, 2018, 12:53:42 pm
Very nice. My 2010 also has the locking toggle switch for the voltage output range. It's a good safety feature.
My TP343 uses one for the tracking switch. So it seems Power Designs were really fond of locking toggles (seen it on other models as well).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on February 09, 2018, 07:24:09 pm
Yep, there's one on my TP343 and TP340A as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: sarel.wagner on February 11, 2018, 07:20:37 am
My 2005 supply is one of the early ones, late 1964. The Circuit diagram is for the later models as per the updates.
Anybody that perhaps have an earlier version please?
(https://i.imgur.com/hP1NLEy.png)

The section in red is missing, assume it was later added as part of the revisions. Have not determined what else has changed yet.
(https://i.imgur.com/hwmMlBn.png)
I have found a number of out of spec resistors in mine this far. Most caps test good, no or extremely low leakage at wvdc.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: orin on February 12, 2018, 02:23:15 am
A little off at a tangent, but I was checking out/repairing my 2005A these last couple of weeks.  I of course blew the fuse testing the current limit pot, so it had to come apart and get cleaned.  My pot has a little 'catch' at about 900 ohms.  I couldn't see any reason for it. The resistance will jitter a little on the meter if the pot is set at this point.  I'll probably have to live with this.  I did give it a dose of DeoxIT FaderLube before putting it back together.

FWIW, here is an hour or so of data with it set to 10V.  You can clearly see the oven heater cycling, but the effect is less than 50uV pk-pk.  (The 34461A's trend plot labeling leaves a little to be desired to say the least; they have room for another digit, but insist on displaying 10.000 2 twice...)

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on February 12, 2018, 03:55:13 am
My pot has a little 'catch' at about 900 ohms.  I couldn't see any reason for it.

Maybe it's worn there from being used around that position for most of its former life.

Quote
The 34461A's trend plot labeling leaves a little to be desired to say the least; they have room for another digit, but insist on displaying 10.000 2 twice...

That's odd also because it's a 6.5-digit meter, so it should have the additional digit. Sure looks weird.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Seich on February 27, 2018, 07:55:09 pm
I finally found a PD2010 in good condition at a reasonable price. I couldn't be happier; it's a lovely piece of equipment. I just need to find a vertical PD2020 complete my collection now.

btw, does anyone know of a good way to get rid of that poor attempt at engraving in the faceplate? I could do without it.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on February 27, 2018, 10:22:56 pm
That's a nice one, Seich. Yeah, the PD 2020 in vertical enclosure is something I've only seen once. Pretty elusive.

Regarding the engraving on the face of your 2010, I don't know of an easy way to restore the metal. You'd have to fill it in and then match the brushed surface texture. Of course, you could just cover it with something that would bother you less than the engraving. Perhaps make your own calibration sticker.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on February 28, 2018, 04:07:41 am
That is a very nice looking 2010, but agree that it could do with out the engraving.

I have a PD 6050C that someone decided to clean-up some stickers using a metal screwdriver and severely gouged the aluminum.
Currently designing a new front panel using Front Panel Designer from FPE, but still need some vector graphics for the pd logo and outer line.

Overall yours looks so good, that I think bitseeker has a great idea of covering the engraving with a well placed cal sticker.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Seich on February 28, 2018, 04:17:02 am
I hadn't thought of a sticker, it sounds like the best option. I just need to find a sticker worthy enough now!

I can't stand people that deface such beautiful equipment. Specially since there are so many spots to add an inconspicuous label on.  :palm:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: hermit on February 28, 2018, 05:28:50 am
I've been thinking lately of the practicality of using something like transparencies with reverse printing and just using that on a front plate.  Easily cleaned and if it gets damaged you just print another.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on February 28, 2018, 05:34:05 am
Nothing wrong with that. It's a lot better than using lots of small transparent labels. You could also put a screen protector over the transparency for a bit more scratch resistance. Transparencies tend to scratch easily.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: David Hess on February 28, 2018, 02:08:33 pm
I've been thinking lately of the practicality of using something like transparencies with reverse printing and just using that on a front plate.  Easily cleaned and if it gets damaged you just print another.

I have done this before and it works great.  The transparency can be held down by a spray adhesive like 3M Super 77 Multipurpose Spray Adhesive.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: hermit on February 28, 2018, 04:46:42 pm
Thanks.  Other than the mechanical parts I was wondering about the best way to hold it in place.  I wasn't sure if thee was an adhesive that wouldn't look bad/blotchy/colored/whatever.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 03, 2018, 08:30:55 pm
Did anyone here win the "for parts" C500 on eBay today?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 03, 2018, 10:28:51 pm
Quote
Did anyone here win the "for parts" C500 on eBay today?

That would be me  :)

Also courtesy of “gto 4ben” I now have a scanned copy of the PD 6150 Instruction Manual with Schematics at the bottom of my blog post.
https://www.barbouri.com/2017/11/30/power-designs-6150-universal-dc-power-source-restoration/ (https://www.barbouri.com/2017/11/30/power-designs-6150-universal-dc-power-source-restoration/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 04, 2018, 12:07:51 am
Cool, congrats. I look forward to seeing the C500. The photos in the listing weren't the greatest.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 04, 2018, 03:27:56 am
Quote
Cool, congrats. I look forward to seeing the C500. The photos in the listing weren't the greatest.

I almost skipped it due to the poor photos. But due to TEA (Test Equipment Anonymous) DPI, and EMI syndrome, I ended up bidding on it and winning by just a few cents.
The bottom of the meter looked a bit sketchy in the photo, but the rest of the front panel looked to be in good shape with plenty of protective dirt and grime.
As usual when the C500 arrives I will give it a good cleanup, and take lots of photos.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 04, 2018, 05:06:09 pm
Quote
This morning I managed to snag 2 A models from fleabay, one working and one not for $100.99 + shipping. The one on the left is claimed to be working. It seems a switch was changed on the other one. Happy chappy me  :-DD

Did you have any luck with your recently acquired Power Designs 2005A's ?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: sarel.wagner on March 04, 2018, 06:44:34 pm
Hi Barbouri,

As it happened yes. I set aside some time today to have a look at them. One is from around 1970 (7043) its got the red switch for 10-20v. It was working from switch on. The calibration was slightly out as received. That was easily corrected. This one switch 0.000 (last decade) resistance is not stable, so the Zero cal drifts around a bit (last two digits) Will have to look into that. There are a few minor cosmetic issues left to deal with.

The second unit is 1972 vintage (72xx date code). This one has the silver lockout switch for 20V selection. It was not working. Did power on, but no output and the 0.000V was -0.370V. Turned out to be an easy fix, F2 (DC Fuse) was blown. This one proved to be dead on Cal. Only the 0V setting required a very minor tweak.

So over the moon with this. I have shot some video. Will assemble and post during the week.

Thank's for asking.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 05, 2018, 02:06:59 am
Nice scores, Sarel. Looking forward to seeing them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: sarel.wagner on March 05, 2018, 09:11:34 pm
So a short video on the pair of PDi 2005A precision power supplies:
on Youtube https://youtu.be/BcwGd8KVZqc (https://youtu.be/BcwGd8KVZqc)
On Vimeo https://vimeo.com/258684831 (https://vimeo.com/258684831)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 08, 2018, 04:42:19 pm
Sarel, enjoyed the PDi 2005A video.
From the date codes my PD 2005A seems to be a 1969 vintage, and has the plastic handle switches for both meter and voltage range select.

The Power Designs C500 arrived this morning. I opened it up to check it out and remove some loose screws that were at one time securing the feet.
Inside it looked in good shape, but the front meter has been damaged by some type of solvent, as I had suspected from the original blurry photos.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 08, 2018, 06:57:31 pm
Looks pretty OK, so far. Yeah, I noticed the cloudy meter lens. If polishing isn't sufficient, you can try hot air. It often clears up the plastic lenses on vintage panel meters. Just don't melt it. ;)

I saw a 5020 recently closed for around $100. Earlier, one sold for over $300. That's crazy.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 09, 2018, 03:02:41 am
The Power Designs C500 meter lens was in very poor shape, and required wet sanding with 1000 grit on a precision flat. I then moved to 1500 grit wet and then finished with Novus plastic polish #2 and #1.
I am happy with the results, and luckily the rest of the front panel just required lots of IPA to remove the 32 years of grime.
The decade voltage selection switch contacts were very dirty and gave varying results when setting voltages. A good cleaning with DeoxIT-D5 and then DeoxIT Gold fixed that problem.
Zero calibration was only slightly off (-250 uV), and at 100V it only required 1.5 mV of adjustment. Noise and ripple at 50% load was around 12 uVAC.
Once again just shows that Power Designs Inc. made some very fine equipment 30+ years ago and is still usable today with just a little care and maintenance.

 Full blog post with more pictures at https://www.barbouri.com/2018/03/09/power-designs-c500-precision-dc-source/ (https://www.barbouri.com/2018/03/09/power-designs-c500-precision-dc-source/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Seich on March 09, 2018, 03:08:18 am
It's looking great now. Good Job!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 09, 2018, 03:37:49 am
Excellent work, Barbouri! :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Seich on March 19, 2018, 09:46:18 pm
In a moment of weakness I bought a 5020 the other day. It was only $52 so the price was just right. It lost a banana terminal on it's way to me so I'll have to replace that. Otherwise is in pretty nice shape with only a couple of scratches and some sticker residue on it's faceplate; the dials and output are still spot on. Pretty happy about it overall. I am running of space for power supplies though. I might have a problem.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 19, 2018, 09:48:30 pm
That's a great deal, Seich. Looks beautiful. I paid about $75 for one.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on March 19, 2018, 10:18:32 pm
Quote
In a moment of weakness I bought a 5020 the other day. It was only $52 so the price was just right. It lost a banana terminal on it's way to me so I'll have to replace that. Otherwise is in pretty nice shape with only a couple of scratches and some sticker residue on it's faceplate; the dials and output are still spot on. Pretty happy about it overall. I am running of space for power supplies though. I might have a problem.

Looks like a great purchase. Too bad about the broken terminal.
I understand about the running out of space. I already have 5 Power Designs supplies, but am still looking for a non-operational PD 2010 in good cosmetic condition.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on March 19, 2018, 11:02:00 pm
In a moment of weakness I bought a 5020 the other day. It was only $52 so the price was just right. It lost a banana terminal on it's way to me so I'll have to replace that. Otherwise is in pretty nice shape with only a couple of scratches and some sticker residue on it's faceplate; the dials and output are still spot on. Pretty happy about it overall. I am running of space for power supplies though. I might have a problem.
Decent price IMHO.  :-+

Worst case, you could just swap the GND banana terminal for the DC- signal, while you wait for a suitable replacement banana terminal.  >:D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Seich on March 20, 2018, 10:57:39 pm
That's exactly what I ended up doing  ;D . I ordered a couple of new posts so it won't stay like that for too long.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on March 21, 2018, 12:26:07 am
That's exactly what I ended up doing  ;D . I ordered a couple of new posts so it won't stay like that for too long.
The workload is increased a bit this way, but it's an old trick that works well IME.   >:D

Oh, and the unit you got looks great cosmetically speaking  :-+ (I really need to clean my TP343B (https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=15&_nkw=tp343&rt=nc&_mPrRngCbx=1&_udlo=50&_udhi=500) up).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 21, 2018, 12:34:47 am
I've got cosmetic projects for mine as well, nanofrog, so you aren't alone in that department.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on March 21, 2018, 12:59:17 am
I've got cosmetic projects for mine as well, nanofrog, so you aren't alone in that department.
In my case it's my most used supply (favorite), so getting time to tear it apart hasn't been all that convenient over the years.

I acquired a GW Instek GPC-3020 from the ITT shutdown stock that ended up on eBay however, so I there's no technical reason I can't get off my butt and take care of my PD TP343B.   :o :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on March 21, 2018, 01:41:32 am
Definitely not a technical reason. :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Luckbad on May 01, 2018, 07:06:59 am
Howdy! Hopefully this is a good topic to reply to rather than starting a new one.

I recently picked up a couple of Power Designs power supplies. These things are gorgeous!

I'm trying to diagnose what's up with the 5015T and figured some of you might have thoughts.

The first issue is that the fine voltage control bounces all over the place as I adjust it. Turning right sometimes increase voltage and vice versa. I'm assuming this is a potentiometer issue and have a replacement on the way.

The second issue thus far is with the meter itself. I can use the screw terminal in front to roughly calibrate it, but at 35V +, the wiper blade (:bullshit: not sure if that's what it is called) bounces side to side and never quite sets correctly. Any thoughts on what I should replace to fix that?

It's able to hold a rock solid 28.00V (what I'm primarily going to use it for) for hours. Amperes will be tested soon once I get a proper load resistor to ensure calibration there.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on May 01, 2018, 12:39:05 pm
Howdy! Hopefully this is a good topic to reply to rather than starting a new one.

I recently picked up a couple of Power Designs power supplies. These things are gorgeous!

I'm trying to diagnose what's up with the 5015T and figured some of you might have thoughts.

The first issue is that the fine voltage control bounces all over the place as I adjust it. Turning right sometimes increase voltage and vice versa. I'm assuming this is a potentiometer issue and have a replacement on the way.

The second issue thus far is with the meter itself. I can use the screw terminal in front to roughly calibrate it, but at 35V +, the wiper blade (:bullshit: not sure if that's what it is called) bounces side to side and never quite sets correctly. Any thoughts on what I should replace to fix that?

It's able to hold a rock solid 28.00V (what I'm primarily going to use it for) for hours. Amperes will be tested soon once I get a proper load resistor to ensure calibration there.
In regard to the fine voltage knob, it probably only needs a good cleaning. Deoxit D (http://store.caig.com/s.nl/sc.2/category.188/.f) would do nicely.

I'm not quite sure what you're asking about on the zero point adjustment screw on the analog meter. FWIW, this is used to set the needle on zero (unit is off) before any voltage or current setting is made via any knob.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 01, 2018, 10:40:04 pm
Howdy! Hopefully this is a good topic to reply to rather than starting a new one.

Sure. This is a good place to get started. If your needs get deep into details, you might start a repair thread for your particular power supply.

Quote
I recently picked up a couple of Power Designs power supplies. These things are gorgeous!

Uh, oh. You're hooked now. ;D

Quote
I'm trying to diagnose what's up with the 5015T and figured some of you might have thoughts.

The first issue is that the fine voltage control bounces all over the place as I adjust it. Turning right sometimes increase voltage and vice versa. I'm assuming this is a potentiometer issue and have a replacement on the way.

As nanofrog said, use a good cleaner such as DeoxIT and it'll probably be fine. Do that before replacing.

Quote
The second issue thus far is with the meter itself. I can use the screw terminal in front to roughly calibrate it, but at 35V +, the wiper blade (:bullshit: not sure if that's what it is called) bounces side to side and never quite sets correctly. Any thoughts on what I should replace to fix that?

It's able to hold a rock solid 28.00V (what I'm primarily going to use it for) for hours. Amperes will be tested soon once I get a proper load resistor to ensure calibration there.

You may want to check how much ripple you have at the output. It sounds like it may be quite severe. If so, then trace the circuit back until you have no ripple or end up at the bridge rectifier (i.e., before any filtering). If you don't have a clean output anywhere along the way, then the filter caps likely need replacing. They're pretty old, so it wouldn't be unusual. But definitely check before replacing. Needless rework increases the odds of something going awry (Murphy, etc.).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 03, 2018, 02:10:44 am
Howdy! Hopefully this is a good topic to reply to rather than starting a new one.

I recently picked up a couple of Power Designs power supplies. These things are gorgeous!

I'm trying to diagnose what's up with the 5015T and figured some of you might have thoughts.

The first issue is that the fine voltage control bounces all over the place as I adjust it. Turning right sometimes increase voltage and vice versa. I'm assuming this is a potentiometer issue and have a replacement on the way.

The second issue thus far is with the meter itself. I can use the screw terminal in front to roughly calibrate it, but at 35V +, the wiper blade (:bullshit: not sure if that's what it is called) bounces side to side and never quite sets correctly. Any thoughts on what I should replace to fix that?

It's able to hold a rock solid 28.00V (what I'm primarily going to use it for) for hours. Amperes will be tested soon once I get a proper load resistor to ensure calibration there.
Very nice set of Power Designs supplies.
Really like the TW6050D unit, and it looks to be in great cosmetic condition.

I ended up replacing the 4 big electrolytic capacitors on the rectifier board, and C8 on the back of the main control board on my 6050D.
Not that familiar with the 5015, but my recommendation is to check all the electrolytic capacitors.
Also fully agree with nanafrog and bitseeker's recomendations for cleaning the voltage control potentiometer.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 07, 2018, 01:44:26 am
Well, I thought I had just the right amount of Power Designs power supplies.
Then this PD 6050C shows up on Ebay with a few minor issues, low price, and free Priority Mail shipping.
It arrives tomorrow.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 07, 2018, 06:56:24 am
Gotta catch 'em all. ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 08, 2018, 02:46:51 am
Gotta catch 'em all. ;D
Unfortunately I do not have the room to  "catch 'em all". But this one did turn out to be a great catch.

I was expecting a full re-cap and maybe replacing a few other components / transistors.
Other than cleaning all that was required was some DeoxIT D5 contact cleaner in the Voltage / Current select switches, and desoldering and reinstalling one of the display sockets that wasn't installed flat.
All the calibrations were perfect, and when testing under full load+ the ripple was less than my Keithley 2015 could measure.   :-DMM
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 09, 2018, 03:14:57 am
Wow! A great catch, indeed.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 13, 2018, 12:03:09 am
A while back idpromnut designed a "drop-in" replacement display board for the Power Designs 6050C digital display.
https://www.eevblog.com/forum/projects/power-designs-6050c-display-mod/ (https://www.eevblog.com/forum/projects/power-designs-6050c-display-mod/)
He didn't publish his board design, so I thought I might make my own.

In researching possible LED 7 segment displays for the board, I came across some larger pin to pin compatible displays from Kingbright that were 0.4" character height vs the 0.3" of the originals.
For a few dollars each, I thought it was worth a try so I ordered 4 of them from Digi-Key.

They ended up working almost perfectly, but were considerably too bright with the existing current limiting resistors.
After swapping out the 47 and 200 ohm resistors with 330 and 1K ohm resistors respectively, I had a larger display on my PD 6050C without the cost of a new board.
This should work for both the PD 6050C & 6050B power supplies.

EDIT: I ended up increasing the current limiting resistors to 750 and 4.7K \$\Omega\$ as the display was still a bit too bright.
         A side benefit of the lower intensity is that the display color has shifted more to a red than the orange-red before the change.


I documented the PD 6050C restoration and modification with lots of photos on my blog post https://www.barbouri.com/2018/05/12/power-designs-6050c-power-supply-display-upgrade/ (https://www.barbouri.com/2018/05/12/power-designs-6050c-power-supply-display-upgrade/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 15, 2018, 03:14:16 am
That looks great, Barbouri! A very nice upgrade, indeed. Is the 6050D display board different from B and C? I only have the A models.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 15, 2018, 04:13:09 am
That looks great, Barbouri! A very nice upgrade, indeed. Is the 6050D display board different from B and C? I only have the A models.
Thanks bitseeker!

The PD 6050D is completely different from the B & C versions, and uses a single chip ICL7117 3½ digit monolithic
analog-to-digital converter.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 15, 2018, 04:26:45 am
Ah, OK. Thanks for the info. Of those three digital variations, do you have a preference? If so, what makes it that much better than the others?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 16, 2018, 05:02:11 am
Of those three digital variations, do you have a preference? If so, what makes it that much better than the others?
I would have to pick the PD 6050D as my preference. They are all great power supplies, and each of them has their own distinct features.
To me it seems that Power Designs, Inc. made an incremental improvement in each revision of the 6050 series that actually improved the usability.
What I like about the PD 6050D is the toggle switch selection of the meter volt / amps display, and the larger display. The front panel layout is also much cleaner and less cluttered.
Internally the control board is still similar to the earlier series, but many components have been upgraded to what at the time was the latest technology.

I may also be biased, as the PD 6050D was my first power supply from Power Designs, Inc.
It was well abused by the previous owner, and I spent several weeks restoring it to near original condition (minus the original knobs).
It is my daily go-to supply when I need a single voltage, and has taken over from my original HP 6200B supply.

https://www.barbouri.com/2017/11/29/power-designs-6050d-power-supply-repair/ (https://www.barbouri.com/2017/11/29/power-designs-6050d-power-supply-repair/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 17, 2018, 01:22:25 am
Heh, that V/A toggle switch on the D seems to have returned from the A series. From an aesthetics point of view, I still like the analog meter on the A, but the digital ones have constant current capability instead of just a crowbar.

The D seems to have even larger digits for its display. Also a nice improvement.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on May 17, 2018, 03:07:03 am
FWIW, I'm fond of the analog meters on my TP343B.  ;D No CC capability, so I use a GW Instek GPC-3020 for that. Oh, and the GPC-3020 also has analog meters.  >:D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on May 18, 2018, 07:30:36 pm
I couldn't resist sharing my 5015A (last cal in 1967!) at max current capacity (1.5A) supplying a state of the art 12-core 1.5GHz processor board. That is why these beasts took mankind to the moon!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on May 18, 2018, 08:05:50 pm
I couldn't resist sharing my 5015A (last cal in 1967!) at max current capacity (1.5A) supplying a state of the art 12-core 1.5GHz processor board. That is why these beasts took mankind to the moon!
That is a nice looking PD 5015A.
Doing what it was designed to do, even after many decades.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 18, 2018, 11:16:09 pm
Yeah, it seems a fair number of these are coming from government surplus, aviation, etc. One of mine is from Grumman Aircraft.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on May 19, 2018, 01:57:25 am
Certainly. Mine is from General Dynamics.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on May 19, 2018, 02:05:43 am
Oh, is that what that sticker is? Cool!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on May 19, 2018, 02:27:04 am
The cal sticker is clearer. I just looked at my post below and realized I got the date wrong: the cal sticker is from 1969 not 1967.

https://www.eevblog.com/forum/testgear/photos-of-your-interesting-and-historical-test-equipment-stickers/msg778659/#msg778659 (https://www.eevblog.com/forum/testgear/photos-of-your-interesting-and-historical-test-equipment-stickers/msg778659/#msg778659)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 02, 2018, 07:22:11 pm
Currently on a trip to visit SWMBO’s mom in Michigan and her alma matter University of Michigan. UM has a property disposition warehouse where they dispose of lab equipment. I convnced wife and kids to make a detour for a visit. Mostly bio lab equipment with  high end microscopes, centrifuges, HPLC equipment, the usual computer crap, etc. But I also found these on a shelf selling for $25 each. My GAS kicked in and I couldn’t resist (despite having way more PSUs than I need).

I decided to look around more first and not carry the heavy beast with me. Soon after, I see one being purchased at the checkout  and rush back to get one of the 2 remaining. There was a guy looking at them a when he saw me grab one he grabbed the last one (though he later changed his mind).  :phew:  It powers up and appears to put out correct voltages. Will load test it when I get home. It will be coming on the plane as a carry on.

(https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=467600;image)
(https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/?action=dlattach;attach=467606;image)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on July 02, 2018, 08:19:17 pm
Wow, I would love to have one of these, especially for $25 with zero shipping. You are a lucky man.  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 02, 2018, 10:00:33 pm
Wow, I would love to have one of these, especially for $25 with zero shipping. You are a lucky man.  :-+

Thanks. Yeah, they are heavy beasts and shipping is a b**** which is why I never considered one before.  But once I was looking at one close up, it was so beautiful, I‘m sure I would have happily paid 4x as much.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 02, 2018, 10:31:40 pm
Two words... YOU SUCK!  :-+
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Bassman59 on July 02, 2018, 10:56:37 pm
I would have to pick the PD 6050D as my preference. They are all great power supplies, and each of them has their own distinct features.
To me it seems that Power Designs, Inc. made an incremental improvement in each revision of the 6050 series that actually improved the usability.

I have a 6050D, too, got it at a surplus 20-some-odd years ago. I use it all the time.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 02, 2018, 11:36:49 pm
Excellent score, mtdoc! GAS or not, it's hard to turn these down, especially when you see one in good condition in person. Even better, you got an early TP340A with metal knobs instead of plastic ones (like mine).

If you run into any issues when you get home, ping me if you need comparisons with a working one.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on July 03, 2018, 03:57:30 am
Great find, Congratulations!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on July 07, 2018, 03:53:43 am
Updated 4-digit display for Power Designs 6050C.

Blog project page for PD 6050C 4-digit display upgrade https://www.barbouri.com/2018/07/07/upgrading-a-power-designs-inc-6050c-with-a-4-digit-plus-mode-display/ (https://www.barbouri.com/2018/07/07/upgrading-a-power-designs-inc-6050c-with-a-4-digit-plus-mode-display/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 07, 2018, 06:46:21 pm
Looks great, Barbouri.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: idpromnut on July 08, 2018, 03:56:43 am
And yes, I have since found the correct replacement for the voltage knob (on the left)! :D

EDIT:  Ha!  I didn't go back far enough, thanks for the shout out!  I'll leave your post with all the glory, damn fine improvement sir!!! :D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 09, 2018, 05:03:11 am
Bigger knob, more potential. ;D
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 13, 2018, 03:38:31 am
I load tested my recent TP340A acquisition and it did just fine. The only thing was an occasional slight flicker of the fault light on Source A.
Opening it up, I found that  R137 was burnt to a crisp. An easy replacement and the fault light flicker disappeared. 

In an effort to see what this 1K resistor was doing and why it might have been burnt, I turned to the schematic. The schematic found in the TP340A manual I've downloaded from KO4BBs manual archive is almost illegible. That site also has a slightly better quality scan of the TP340 manual which is somewhat legible. But alas - no R137 on that model.  In any case, it appears to be part of the crowbar circuit. Inspection did not reveal any other obvious issues and none of the always suspect tantalums appear shorted, so hopefully it will remain problem free.

If anyone has a clearer version of the manual or schematic, it would be much appreciated.

It was impressively clean inside and aside from the one burnt resistor, appeared almost brand new. It's interesting seeing some of the component changes in bitseekers newer unit (https://www.eevblog.com/forum/repair/power-designs-tp340a-repair-and-facelift/msg769284/#msg769284). Best I can tell from date codes is mine was manufactured in the mid 1980s.

I'm really quite impressed with this unit. There are not published specs on the noise and ripple, but on my testing it was in the neighborhood of 50 uV,  similar to my PD 2005a, 2010 and my HP 6114 and 6115s.



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 13, 2018, 03:58:21 am
FWIW, I suspect it would survive load testing (these things are built like tanks IME).  :-+

If not, there's surely someone that can post a proper schematic (I've a TP343B if that'll help; bit different obviously, but the offer stands should you need it).
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 13, 2018, 04:35:46 am
FWIW, I suspect it would survive load testing (these things are built like tanks IME).  :-+

If not, there's surely someone that can post a proper schematic (I've a TP343B if that'll help; bit different obviously, but the offer stands should you need it).

Oh it did pass load testing just fine - even before I replaced the burnt resistor. I just don’t like not understanding why that resistor blew.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 13, 2018, 05:10:20 am
Unfortunately, I don't have a better schematic. Perhaps someone did something funky with tracking since source A was affected.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 13, 2018, 11:44:21 pm
FWIW, I suspect it would survive load testing (these things are built like tanks IME).  :-+

If not, there's surely someone that can post a proper schematic (I've a TP343B if that'll help; bit different obviously, but the offer stands should you need it).

Oh it did pass load testing just fine - even before I replaced the burnt resistor. I just don’t like not understanding why that resistor blew.
I get it.

I'd be in the same boat should something happen to mine (would do my darnedest to figure out the issue and fix it, even if it ended up being more expensive than just replacing it with a working unit).  :)

They're just way too pretty to let go to a landfill IMHO.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JonM on July 16, 2018, 03:31:46 pm
About 36 years ago I saved a Power Designs 2005 from a dumpster and gave it to my father who had it hanging under a cabinet in his shop since then. After becoming an EEVblog fanboy I was surprised to see a 2005 on Dave's shelf and the video about it.

I recently recovered this power supply and did a bit of testing. The first problem was that the voltage was high by almost a full volt. That turned out to be due to the 0.1 v dial reading zero but actually being set to 9. With some difficulty I got it set properly. I did mess with the calibration pots before I noticed what was causing the 0.9 volt offset, so the 5.00018 v is not from a 40+ year old calibration.

The power cord is in very bad shape but before changing it I would like to loosen the 0.1 v dial shaft to make this supply be actually useful. If anyone has a recommendation please let me know. I was going to try some contact cleaner / lubricant spray but I suspect that it will not be enough of a lubricant.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: KrudyZ on July 16, 2018, 05:41:07 pm
I'm not sure if you noticed, but the vernier on your unit in the photo is set to 8.
So if you want to calibrate this to better than 1 mV then make sure to take that into account.
I have one of these and they have incredibly low drift and great repeatability once the heater has stabilized.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: JonM on July 17, 2018, 02:25:06 am
I'm not sure if you noticed, but the vernier on your unit in the photo is set to 8.
So if you want to calibrate this to better than 1 mV then make sure to take that into account.
I have one of these and they have incredibly low drift and great repeatability once the heater has stabilized.

Thanks, I did notice the vernier position just after I posted (actually I thought that some dirt in the photo was the knob mark and then looked at the unit and saw the vernier was cranked up).

The first task is to get that 0.1 v position to move reasonably.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 17, 2018, 03:02:09 pm
The first task is to get that 0.1 v position to move reasonably.
I recommend going with Caig Deoxit (http://caig.com/) products. It's not cheap, but works extremely well. The K-2C sampler kit (https://www.ebay.com/itm/Caig-DeoxIT-Sampler-Kit-K-2C-Shield-S100L-FaderLube-F100L-D100L-G100L-Gold/302693316727?epid=1203632960&hash=item4679ed7877%3Ag%3AW6wAAOSwikdaxIDp&_sop=15&_sacat=0&_nkw=caig+kit&_from=R40&rt=nc) would take care of your 2005.

They do sell spray cans, but you'd be better off disassembling the pots and clean them that way IME.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 20, 2018, 02:49:04 am
Decided to do further noise testing of my recently acquired TP340A.  When I attached my scope to the output of source C the fault light lit up.  Tested and there was about 6 kohms between the negative output and ground. Not right! It is supposed to be an isolated supply.  Nothing obvious on inspection of the boards. The only connection between ground and the negative output is supposed to be via a couple of ceramic caps which I checked and were fine. After some tracing I isolated the problem to an orange wire leading to the V - A switch. Looking closer and aha!  The orange wire had been pinched between the frame and front panel - presumably when someone had taken it apart or loosened those screws.  I'd missed it on my earlier inspection. Easy fix. :phew: 

It's a testament to how well these things are built that even with this 6kohm connection between the negative output and ground, source C still passed preliminary load testing.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 20, 2018, 04:15:45 am
That's a sneaky fault. Good sleuthing, mtdoc.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on July 22, 2018, 09:29:08 am
2mtdoc: are these wires, soldering and cable ties original? It all looks very well and tidy for such an old piece of equipment.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 22, 2018, 03:52:33 pm
Yep, all orginal AFAIK. The PD supplies are like that.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: nanofrog on July 22, 2018, 04:10:15 pm
Yep, all orginal AFAIK. The PD supplies are like that.
They are.  :-+

I noticed a date code in one of your photos (RCA TO-3) of 8501. I suspect it's original, but do you recall if '85 is right based on other components?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on July 22, 2018, 04:12:40 pm
2mtdoc: are these wires, soldering and cable ties original? It all looks very well and tidy for such an old piece of equipment.
I have always been impressed with the quality of the wiring and attention to detail in the Power Designs Inc. supplies.
Here is a picture of the bottom view of a PD 6150 hand laced wiring harness.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mtdoc on July 22, 2018, 05:04:13 pm
Yep, all orginal AFAIK. The PD supplies are like that.
They are.  :-+

I noticed a date code in one of your photos (RCA TO-3) of 8501. I suspect it's original, but do you recall if '85 is right based on other components?
Yes, I think it is. If you compare my photos to Bitseekers in his repair thread (link in my earlier post), you can see there were several part changes in later models.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on April 14, 2019, 06:58:56 pm
Hello power designs lovers,

Do you think it's possible to convert 2005A to accept 230V input? I'm trying to figure this out from tear down photos: https://www.barbouri.com/2018/01/13/power-designs-2005a-precision-power-source/ (https://www.barbouri.com/2018/01/13/power-designs-2005a-precision-power-source/) . Looks like a new transformer is needed :(.

BTW, what power designs suplies have ovenized references? I know about 2005A, but I wonder if oven is used in their other models.

PS I see "Warning: this topic has not been posted in for at least 120 days. Unless you're sure you want to reply, please consider starting a new topic." Should I start a new topic, or keep it contained in this one?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 14, 2019, 10:03:37 pm
Your post is relevant since the 2005A is a precision supply.

As far as I know, you'd need a different transformer for 220V operation.

Of the precision models, the 2005, 2005A, 2020A, and 4010 (not very common) use an ovenized reference. Note that there are also non-precision 4010 models (fairly common). They don't use an oven.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on April 15, 2019, 12:19:43 am
It looks like the 2005A was only built with a single 115V transformer primary winding.
The transformer part number is TTN-56 built by Power Designs, Inc.
Terminals 1, 2 are the primary.
Terminals 3, 4, 5 secondary #1 and 6, (7), 8 secondary #2 with terminal 9 transformer ground.

Most likely your least expensive option would be a 230 to 115V external step-down transformer, 50VA or larger.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on April 15, 2019, 09:20:58 am
Thanks for the information! I'm thinking which one I'd like to get: 2005A or 2020A :).

Are 2005A and 2020A different in width and height? The specs say so, but looking at photos they seem to be fairly identical. At least the front panel.

What model would you recommend? 2020A seems to be quite more powerful.

2005A seems can be fairly easy "upgraded" to 230V just by replacing a transformer. 2020A has a third winding with quite high voltage. This can complicate replacement.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on April 15, 2019, 06:50:26 pm
They do look like they're the same height/width, but I don't have both, so I don't know for sure. My collection currently consists of all non-ovenized models (precision ones in bold): 2010, 2020B, 5020, 2015R, 3650-S, 6050A, TP340A, TP343B.

If you specifically want a precision version with oven, then the 2020A. Otherwise, the 5020 covers the 20V, 2A of the 2020 plus has the capability to go up to 50V at 1A.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on October 26, 2019, 10:34:00 pm
Sorry to revive such an old thread, but I read this today and was interested enough to do a little research on these mystery boxes on my own.
I found this picture of a PD catalog someone is selling on ebay. I've attached a picture from the cover, as well as the link to the item if anyone is actually interested enough to buy it (I am not the seller and have no affiliation). I also tried to find a scan of this floating around on the 'net somewhere and came up emptyhanded.

What I thought was interesting about this picture is that it shows the "newer" digital models along with the older precision supplies, although I can't make out which one it is. This was at one point in time at least, their lineup prior to the acquisition of their branding and the change that followed. An interesting time for a PD catalog, and I'd like to see what's inside if anyone else has found a scan of it somewhere.

https://www.ebay.com/itm/Power-Designs-Regulated-DC-Power-Sources-Product-Catalog/323203742840?hash=item4b4071bc78:g:i0gAAOSwZ-Zazm~L (https://www.ebay.com/itm/Power-Designs-Regulated-DC-Power-Sources-Product-Catalog/323203742840?hash=item4b4071bc78:g:i0gAAOSwZ-Zazm~L)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on October 27, 2019, 11:31:52 pm
What I thought was interesting about this picture is that it shows the "newer" digital models along with the older precision supplies, although I can't make out which one it is.
Hi Johnboy,
Power Designs Inc. never did make a true digital control model power supply.
After the acquisition they came out with the plastic cased models: 5020A, 2040A, and 1001A Precision DC Power Source units, which I believe were considered their digital models.
These were basically repackaged existing power supplies with a push-button decade switch on the front panel that selected a combination of different resistors vs. turning a potentiometer.
I have never owned one of these so called digital units, but I have read that these were built to a price point, hence the plastic case.

Greg (Barbouri)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on November 04, 2019, 03:58:36 am
Sorry to revive such an old thread, but I read this today and was interested enough to do a little research on these mystery boxes on my own.
I found this picture of a PD catalog someone is selling on ebay. I've attached a picture from the cover, as well as the link to the item if anyone is actually interested enough to buy it (I am not the seller and have no affiliation). I also tried to find a scan of this floating around on the 'net somewhere and came up emptyhanded.

What I thought was interesting about this picture is that it shows the "newer" digital models along with the older precision supplies, although I can't make out which one it is. This was at one point in time at least, their lineup prior to the acquisition of their branding and the change that followed. An interesting time for a PD catalog, and I'd like to see what's inside if anyone else has found a scan of it somewhere.

Cool find, Johnboy. The models on the cover, as far as I can tell given the low resolution and excessive compression of the seller's image (clockwise beginning at the top-left):

1. TP340 or TP343A, triple-channel. It looks like there may be an 'A' designator at the end, so it may be a 343A. The TP340A has positive and negative binding posts for Source A and B, whereas the non-A is positive for Source A and negative for Source B (as in the image). The TP325 has a single line of lettering at the top, whereas the 340 and 343 have two-line lettering.
2. TW347?, dual-channel. I've only seen the 'D', digital, version of this.
3. 2020B or 2010, precision supply. By contrast, the 5020 doesn't have a range toggle between the amber/yellow lamps and the 2005A has an additional oven lamp.
4. 6010(A/B/C/D)?. I've never seen the digital version of this, but the range table on the left side of the panel looks like the one on the analog 6010.
5. 3K10, high-voltage supply (3000 V, 10 mA)
6. 6050C. The 6050D has lamps on either side of the display, like #4, but with four ranges instead of the three in #4.

Corrections welcome.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 05, 2019, 07:25:32 pm
I am curious as to whether there is an MSRP included alongside the various models, as there is only one mention in this thread of what that might have originally been for only one model. If the cover is indicative of the main models they were offering at the time, which appear to be from the New York factory, it might be interesting to see what demographic they were aiming for in terms of marketing. Who was this flashy catalog for? Posters in this thread have reported finding stickers by big-leaguers like Grumman, Boeing (IIRC) and I have even seen a unit that was marked as property of Sandia National Laboratories. PDI seems to have been at one time making high-end test gear for military contract, a rather solid gig if you don't get greedy and start counting beans (which does not seem to be the MO of this company, at least until manufacturing left New York, and it's not clear why that happened either). I find it exceedingly strange that there were so many people who posted in this thread, over several years, and only a very few were able to find much information about this company at all. Surely PDI held some patents and someone had to take personal credit for the designs, at least at some point? This company was churning out rather unusual, visually-striking products for multiple decades. It seems very odd that there was so little left to find.

Unless, of course, they were aliens.  :horse:
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on November 05, 2019, 07:31:33 pm

4. 6010(A/B/C/D)?. I've never seen the digital version of this, but the range table on the left side of the panel looks like the one on the analog 6010.
(https://www.barbouri.com/wp-content/uploads/2019/11/PD6010Dfront10.jpg)
Power Designs Inc.  6010D  Universal DC Source
Greg (Barbouri)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on November 06, 2019, 08:38:17 am
It seems very odd that there was so little left to find.

Unless, of course, they were aliens.  :horse:

I have same thoughts. I'm surprised how many models they released. Would love to know the company history.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on November 06, 2019, 08:42:37 pm

I have same thoughts. I'm surprised how many models they released. Would love to know the company history.

Hi Johnboy and exe,

Tech Obsessed has a Power Designs Inc. History page
https://techobsessed.net/power-designs/

From my research the information on "Tech Obsessed's" page is pretty accurate with the exception of.

August 2006 - Solomon Technologies, Inc. announced that it has completed its acquisition of Technipower LLC, a Danbury, Connecticut-based manufacturer of power supplies and related equipment for the defense, aerospace and commercial sectors.

My research shows that Unipower LLC acquired Technipower in 2011, not 2012.

Greg (Barbouri)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on November 07, 2019, 10:45:51 am
Tech Obsessed has a Power Designs Inc. History page
https://techobsessed.net/power-designs/

Thanks, Greg! I was hoping for a bit more, like a history from human perspective. Like, two friends got drunk in a garage, designed and assembled their first power supply over night, sold it with a good profit, then they decided to establish a business...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: rsjsouza on November 07, 2019, 02:32:38 pm
Tech Obsessed has a Power Designs Inc. History page
https://techobsessed.net/power-designs/

Thanks, Greg! I was hoping for a bit more, like a history from human perspective. Like, two friends got drunk in a garage, designed and assembled their first power supply over night, sold it with a good profit, then they decided to establish a business...

There is no history. Some of us believe something is really fishy with them:

As someone else hinted in a past discussion, I am suspicious they were in fact from another planet and graced us with their designs...

Glad someone else believes this, since there is no internet history on them.  If something exists then it will be on the internet.  Since "they" do not exist but their products exist, something must be going on.  A logical explanation is aliens made them for some purpose that we do not know about.  Like help develop something for space flight that will take us to another planet.  Once this theory is proven then the value of these supplies will greatly increase.  I just hope humans will not become a food source like I think about every time I look at my power supply.  God forbid, the PD is not the alien (but just in case I use kind words when I talk to my power supply)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 08, 2019, 08:23:38 pm
Thanks, Greg! I was hoping for a bit more, like a history from human perspective. Like, two friends got drunk in a garage, designed and assembled their first power supply over night, sold it with a good profit, then they decided to establish a business...

Well, as it turns out, you get your wish. I just got off the phone with the son of one of the Power Designs engineers, and some of the stories he told me are, frankly, fascinating. He seemed very surprised to hear from someone about the company, as his father was apparently more well-known for his later work with Venus Scientific. Unfortunately he passed away five years ago, so I cannot interview him directly. His son told me that his father was decorated with a gold pin for his design contributions to the Apollo missions for a power supply that went to the moon (!). So the "aliens" jokes can die now; I guess the aliens are us.

The son said he would go see what he can find of his father's stuff related to Power Designs and will update me, and would appreciate any additional info we can dig up. I am collecting a list of links and other info to send him.

I'm not sure if I should post what I've learned here in this thread, or on eas' comment page, or make a new thread, or what. But there is obviously quite the story here, and I've been given a few new bites of info to work with that may produce even more information. I'm open to any suggestions.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: vindoline on November 08, 2019, 08:41:22 pm
Johnboy, this sounds really interesting! I would vote for adding the info to this thread to keep the PD info all in one place.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 08, 2019, 09:26:10 pm
Johnboy, this sounds really interesting! I would vote for adding the info to this thread to keep the PD info all in one place.

Noted. Maybe it should be put to a vote.

There are a couple of reservations in my mind about spilling here. This is an international forum, and this thread alone has hundreds of thousands of views. My bloodhound game wouldn't be difficult for many of the more IT-savvy members here to duplicate, to say nothing of the ghostly guests. The last thing I want is this poor guy to regret having ever called me back after receiving a bunch of calls in the middle of the night about the Power Designs company from all corners of the globe. He at one point even offered to send me a picture or two of his dad at work, so if that means anything to any of you, I would appreciate all of you letting me "lone wolf" this particular source of information for now.  If he becomes annoyed, that will also likely be the last of any information or cooperation from his end. With your collective discretion, we may be able to give something back (in a way) to the designer of these instruments. There are other family members still alive whom I haven't been able to contact directly yet, but their stories may also shed more light on the history of this company and its designs, so it's vital that that process doesn't get unduly replicated by well-meaning, incurably-curious entities, because then they'll start to avoid us. I'm not being grandiose here, I have just realized that this could backfire spectacularly. I'd like to have a list of questions to ask them when I call back, and I'd strongly encourage you to add your own, so I can do it right. Unfortunately the son is not an engineer (interesting story about that as well) so they can't be the technical questions we'd all like to ask of the designer himself. However, more broad questions about PDI that I might not have thought of would be great. Again, I am asking for all your cooperation, not demanding it. I'm probably as curious as most of you.

EDIT: I'm obviously also a little out of my depth here. If any of you have any private ideas as to how I might share without accidentally creating a problem for this guy, please PM me.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Melt-O-Tronic on November 08, 2019, 10:46:03 pm
Wow, this is awesome, Johnboy.  I first became aware of Power Designs through this thread and encountered my first one in the wild last year at a hamfest.  I'm at least as curious as others here about the history and -- as the History Guy says -- it's history worth remembering!  The sheer engineering quality is enough to make the company history worth saving for posterity, as much as Hewlett Packard's history.

I don't have any input regarding your source's privacy, other than I hope he realizes that there is a significant thirst for understanding out there, precisely because of the wide appreciation for & admiration of the work done by PD.  I hope he finds that a blessing rather than a curse.  Offering him right-of-review before publication may be helpful.

THANK YOU for researching!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on November 09, 2019, 12:28:08 am
Power Designs Inc. advertisement from "Electronics" magazine 1961
$339.50 in 1961 with inflation would be around $2,900.00 in 2019
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 09, 2019, 06:44:03 pm
This probably belongs in this thread as well.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alextwin007 on November 09, 2019, 10:41:25 pm
I'm glad this thread is active again so I can show off.  I got a 4010 from a coworker at a hamfest.  I was buying a Tek 214 from him and I just fell in love with the dials of the interface.  I got it in non-working condition, I was told it was calibrated a few decades ago and that he loneed it out and it just stopped working, but since he had another one he didn't put the time in to figuring out what was wrong.  Looking up info for this model I found there was little out there, and upon going through this thread it seems that this one is somewhat rare.  In the end I was able to replace a resistor and a blown internal fuse, and some deoxit and I got it working.

As mentioned earlier in the thread, as a usual hobbiest I have no way to calibrate it as it is more precises then any of the meters I have  :o.  I currently use it as my go to power supply and a voltage reference.

I'm also interested in hearing about the history of this company as well since there is so little info on them.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 10, 2019, 04:34:09 pm
Ok, so after some thought about this matter, I've decided to write about my brief interview with the son of one of the engineers at Power Designs. Spoiler: There isn't a great deal of new info about PDI as a company here, but some of you may find this interesting anyway, as I did.

The gentleman I spoke to is the son of Arthur Silver. For those of you who may have never heard that name before, he was the man who is credited with inventor status regarding the Uniply patent. The early Power Designs models had "patent pending" screened on them, before "Uniply" appeared on most of the models. I am quoting from memory here, but IIRC the patent was awarded in 1971. However, the patent process (as no doubt some of you know firsthand) can be a long and tedious process, and it was likely even more so in the 1960's. My interviewee (henceforth called "Sonny" to give him a modicum of privacy) was very young when Silver first started working for PDI, but he seemed fairly certain that his father had been an employee of the company, rather than the owner or founder. He was unaware of his father's status as stated inventor of the Uniply, and it seems that since Silver was working for PDI at the time of the patent request, the company probably had some contract with him that specified that the inventions produced under their bannerhead was their property. This is, of course, something design engineers commonly sign off on in order to have access to advanced equipment, materials, and funding for their work.

At any rate, we can be fairly certain that Silver was working for PDI by the late 1950's. He was not a man who brought his work home with him, so to speak. I did ask whether Silver had been "chummy" with the other engineers or his boss, brought them home for dinner, etc. It seems Silver kept his home and work life separate. I had hoped to get the names of other engineers, techs, or coworkers that I could cross-reference and later possibly interview, but it doesn't seem that they were exactly fixtures in the Silver household.

I will toss up for consideration the possibility that Silver's work was considered of a sensitive nature, due to its applications and PDI's status as govt/mil/space contractor, and that PDI actively discouraged discussion of their products and designs outside of the laboratory. I do not have much to support this inference other than that I and others have been able to find almost nothing about the company itself. The only other name I have found in association with PDI is that of Melvin Becker, who seems to be associated with the change in location of manufacture to Connecticut. This latter was the place where the very-different-looking precision models seem to have first appeared (the 5020A and the 1001A are a couple of examples). These seem more similar to the 611X models produced by Hewlett Packard in form if not in function: Those cool looking concentric knobs must have appeared rather old-fashioned to eyes of that time period, and in the latter days of the Cold War period it was very important for any US tech company to keep up appearances of being on the knife edge of manufacturing and design. I do not know what happened to PDI by this time, but it appears that this change in format to a modern interface was not a "big hit" with industrial purchasers. Perhaps by then Power Designs was synonymous with tank-like appearance and build, and engineers familiar with earlier models were not as trusting of the new, plasticky models (with the older form factor, to boot: I've noticed that the newer models seem to be using the analog meter style that shows a vertical "arc" to the left of the needle, rather than the straight-up-and-down vertical meters. This was the older style of meter; If you search you can find some 5020's for example that have the arc meter style, but don't have the Palo Alto printing on them yet). Some have supposed elsewhere in this thread that this later incarnation of PDI was merely repackaging older stock and putting a new face on it to present the appearance of a newer, more advanced model. If true, this was unlikely to have gone unnoticed by the engineering community, and may have undercut the perception of the company's integrity, warranted or not! 

It is also significant that Silver himself had almost certainly moved on by that time anyway; I'll get to that in a moment, as I'm back to referencing the 1960's decade here. Sonny told me that his father was, unsurprisingly, a very smart guy. He volunteered that his school science projects he and his father built together were the marvel of the teachers and students (one of them was a lie detector; although I didn't ask Sonny exactly how it worked, I can only imagine the stunned faculty members watching Sonny walk into the science fair with a homemade polygraph in a box under under one arm). Silver was given to improvising solutions around the house, as well; Sonny recounted his father melting down fishing weights and pouring the molten lead into beer cans to create counterweights for a home designed pulley system Silver used to operate a door he had added to the house. His children were also recruited to assist with these home improvement projects. One of the stories I heard is that Silver decided he was going to do some excavating in his backyard and the kids were all handed shovels to dig it up by hand. I think it's notable that this guy was the sort of resourceful individual who wasn't going to hire in a bunch of outside operators or contractors to get things done; he did it himself or had his immediate family pitch in to help, and he could work with whatever was at hand to accomplish his goals. Sonny mentioned a picture of his father at work on circuits at his desk wearing a bow tie; while I haven't yet seen it, I hope to be able to post it here if and when I can get his permission to do so.

I asked Sonny about his own background and whether his father talked often about Power Designs. He told me that he was a child during the time period that Silver worked for PDI, so he didn't hear much about it. However, he did tell me that his father came home from work on more than one occasions very excitedly talking about the new laboratory he had access to. Apparently, they had a room where he could test the  circuits he was building at very low temperatures, and one can only assume that the circuits were working well under those conditions, because Silver seemed very happy about this development and new access, rather than frustrated or concerned.

For those of you who've read my earlier post, Silver was at some point awarded a gold pin for his contributions to the Apollo Program(s). Maybe he could not be honored in other, more public ways, because of the Space Race and the need for the US to keep its best engineers' identities a secret from foreign interests. I don't know. But again, the fact that Silver was working on power circuits in a cold lab suggests that this might well have been meant to simulate how the circuits might function in the extreme cold and vacuum of space. Sonny did say that he recalled his father saying that one of his designs actually went to the Moon. It would be almost comical to see a picture of Armstrong or Aldrin supported in the background by the image of the iconic PDI robot with his hand up, limiting current, and the words "patent pending" beneath.

I apologize for the fact that I have made so many guesses in this post. Should more information come to light (and I do hope it will!), I'll happily edit what I've written here. I have likely made some errors. I did my best to keep notes as I talked with Sonny, but the time periods between Silver's tenure at PDI and Venus Scientific isn't clear (may have even overlapped?). Sonny did volunteer that he'd see if he could find any of his father's stuff related to PDI, and asked me to update him as well. I think he was more than a little touched that so many people thought so highly of his father's work and designs (and I'll make one more guess; that for security reasons, among others, Sonny had never been told just how important his father was as an asset to the programs he worked on). I'm hoping that some of you will also continue the effort, as eas and Greg have, to bring the real story of PDI to light, and I will continue to post with any new info I can find myself. I also intend to send Sonny a copy of this thread so that he can see how this thread developed, from someone asking about a recommendation for a lab power supply, to almost a detective novel.

Thanks to all who have posted in this thread thus far.


Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 10, 2019, 05:41:53 pm
...And I'm aware I'm likely to get ripped apart for making so many guesses. Frankly, I don't care. You're not tearing me down by pointing out my mistakes or leaps of logic, you're helping out.

rsjsouza pointed out that there is a feeling of fishiness about PDI, and unfortunately, most of the evidence we have is that by omission, rather than having the duck in the hand.

Yet, I'll vouch for some of my guesses by summarizing a few things noted elsewhere in the thread, to save having to reread it in its entirety (although I don't discourage that at all!):

1. There was an [edited] discussion of why these low-power, highly stable precision units were necessary at that time and why they aren't widely produced anymore. Those of you who read it before the edits know what I'm referring to.

2. The units incorporating the Uniply design seemed to emphasize a main selling point of being able to do their own switching between ranges, "taking the place of multiple power supplies". One can see the potential value of a single unit being used to replace multiples in a situation where every ounce of weight has to be taken into account.

3. There is a documented story of Bob Pease being handed a Power Designs schematic that had "stumped" other engineers who'd been asked to look at it, and making the assertion that "you'll never understand how this works until you redraw this" (sic). Although it's likely that there were many different ways taught to sketch a design, I am vouching for the possibility that Power Designs product schematics might have been deliberately drawn in this way to prevent "the wrong eyes" from taking it in at first glance. It's also significant that so many of the manuals and schematics for these instruments are simply not available. Where did they go? Consigned? Locked away? Destroyed?

4. There seems to have been a retail consumer push at the end of the company's life, as evidenced by the picture of the color catalog. But what we don't see are consumer advertisements for the PDI products in magazines, or catalogs, of the earlier days. That doesn't mean they're not out there, and maybe the early PD stuff was so expensive that they didn't bother asking if Joe Blow was interested. Yet that is begging the question-- who were they really trying to sell these units to?

Hence all this guessing. I have more questions than answers, honestly.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: dom0 on November 10, 2019, 05:46:47 pm
Quote
he did tell me that his father came home from work on more than one occasions very excitedly talking about the new laboratory he had access to. Apparently, they had a room where he could test the  circuits he was building at very low temperatures

I imagine most engineers would be excited to work on "space-electronics", in the 60s no less.

Quote
1. There was an [edited] discussion of why these low-power, highly stable precision units were necessary at that time and why they aren't widely produced anymore. Those of you who read it before the edits know what I'm referring to.

?

Quote
2. The units incorporating the Uniply design seemed to emphasize a main selling point of being able to do their own switching between ranges, "taking the place of multiple power supplies". One can see the potential value of a single unit being used to replace multiples in a situation where every ounce of weight has to be taken into account.

The uniply design is, as far as I can tell, very similar to something I came up for a 500 V lab supply. (It's not terribly complicated). This line of thought is a lot better under dynamic conditions than the stuff HP/Agilent used for automatic internal range switching, and of course way superior to anything using relays. These latter approaches are a bit like a programmer's view on circuit design: "Okay, my series pass element cannot take this load. So let's add something in front of it to deal with that."; the uniply design is the holistic approach "Okay, a single series pass element cannot take this load. What if I transpose a parallel, current sharing design to the voltage domain? A compound pass element with multiple inputs that by virtue of silicon uses the input to match the output?".

Quote
[weird schematics]

The inverted schematics, negative at the top, and positive at the bottom, with conventional current flow going upwards, were pretty common in the 60s. It also seemed to be somewhat common to "obfuscate" schematics in manuals and patents to make it less obvious how they work.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 21, 2019, 08:18:28 pm
Since PDI's production spanned multiple decades and included so many models, I feel that assembling a comprehensive timeline would be very helpful in facilitating further investigation. Forum member eas has already published a partial one:
https://techobsessed.net/power-designs/

In order to fill in the gaps, one of the things I think worth determining is whether the serial numbers on the individual models can tell us anything of import. Those of you who have done teardowns and looked at the date codes on internal components may be able to help by cross-referencing approximate year of the codes with the serial number of your unit to see whether there is a key of some kind. Specifically, one thing I'd like to know is whether we can discern what year the Palo Alto markings began to appear on the screen printing.

Here is a unit which recently sold on the American auction site, and which has some unusual features, based on the other units I've seen in this thread.
 
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alextwin007 on November 21, 2019, 09:35:12 pm
That looks similar to the 4010 that I have, just the max current and voltage are different.
What I find very unusually is that it doesn't follow the normal naming convention that many of the other PD power supplies have.
If I get time I'll open up the 4010 I have and take a look, although since the 4010 is a rare model (looking through this thread I only found 1 other) there won't be many data points for it.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 21, 2019, 10:40:03 pm
Yes, yours seems to be one of the less-spotted ones (IIRC, it's the precision model used as a comparison in "The Art of Electronics" mentioned elsewhere in the thread). I see an inventory sticker which appears to read 1973 in the upper right corner, so we can safely assume it was built before that. Also, yours does not have the Palo Alto printing, unlike the C400 in the pic I attached above. Both have ovens.

I'm also attaching a picture of my own C500, which has no oven but is also lacking the Palo Alto printing. :-//
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on November 22, 2019, 06:40:09 am
Yeah, the usual numbering is voltage followed by current. For example, 4010 is 40V, 1.0A. The 2005 is 20V, 0.5A.

With the C400 and C500, the voltage is 100, so they use C, which is 100 in Roman numerals, to save space. Clever, eh? Small high-voltage power supplies typically provide current in mA, so PD used mA in the model. Thus, C400 is 100V, 400mA and C500 is 100V, 500mA.

I believe the C400 is older than the C500 as the former has an ovenized reference, but the latter doesn't. Similarly, the 2005 has an ovenized reference and the 2005A doesn't.

It would be interesting to see what could be gleaned from serial numbers, including whether the numbers reset and, hence, end up telling us little.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Sparky on November 22, 2019, 06:52:05 am
With the C400 and C500, the voltage is 100, so they use C, which is 100 in Roman numerals, to save space. Clever, eh?

Very clever! I think this is inside baseball type knowledge; only TEA-member will know!
Sparky
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on November 22, 2019, 05:35:43 pm
A TEAdvantage? :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Sparky on November 22, 2019, 07:55:17 pm
A TEAdvantage? :-DD
  :-+  :-DD
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on November 22, 2019, 08:39:58 pm
Here is my contribution to the Power Designs, Inc model and serial number database.

Model        Serial #     Component Date       Status                       Location           Logo         Other
6050D       803035             1987                Operational                Westbury, NY   pd            Full re-cap
6150         410074             1984                Operational                NY / CA           pd            Partial re-cap
2005A       906027             1969                Operational                Westbury, NY   pd            Replaced C3
6050C       705017             1987                Operational                Westbury, NY   pd            Modified display, replaced C8
6050C       705038             1987                Operational                Westbury, NY   pd            Modified display, replaced C8
C500         605008             1985                Operational                Westbury, NY   pd            Original caps
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on November 22, 2019, 11:27:32 pm
Thanks, Barbouri!

I see your 2005A does have an ovenized reference. I thought all the 2005A eliminated the oven. It'll be great to get all this info in one place to learn from the patterns.

Johnboy is making a new thread for collecting general (i.e., not just precision models) PD identities. I asked him to post a link here to the new thread and we can continue documenting over there.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: CatalinaWOW on November 23, 2019, 05:02:39 am
The attached pictures of a 2005A (no longer in my possession) shows an ovenized version.  PO sticker on the back dates it to 1973 and there is a serial number to track that part down.

More grist for the patterning mill.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: HalFoster on November 25, 2019, 12:51:47 am
The collection so far... I'll get the SNs together and post them and other details if it will help.  I love the PD supplies and would also like to find out more of the history of the company as well as document their products.

Hal

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: HalFoster on November 25, 2019, 12:52:24 am
And the rest...
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Johnboy on November 26, 2019, 04:02:40 am
New PDI Database Thread:
https://www.eevblog.com/forum/testgear/power-designs-power-supplies-database/ (https://www.eevblog.com/forum/testgear/power-designs-power-supplies-database/)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: kj7e on January 10, 2020, 06:20:10 pm
Picked up a 2020B that needed a little bit of love.  Dirty switches, a few resistors drifted a bit, needed a good general cleanup.  Overall in good shape though and the prices was right for the LM399 referenced model.  The analog meter is not very linear, just a sanity check is all its good for.  The tracking of the dial settings is well within spec but I had to add a 3.9 ohm resistor across the 1 ohm 0-1mv pot to get it to track better.  Also added 6.9 MOhm across the 10K range selector resistor to get the 0-10v and 10-20v ranges to track better.  Checked the larger AE filter caps with my LCR meter and they appear fine.

Found a good high quality scan of the 2020B manual, includes 5020 and C500;
https://wp.geekfun.com/wp-content/blogs.dir/22/files/2015/10/Power-Designs-5020-Precision-Power-Source-Manual-Newer-Edition.pdf

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: kj7e on January 10, 2020, 06:22:28 pm
After some fine tuning.  The greatest error is at 5v.



Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: kj7e on January 14, 2020, 02:35:24 pm
Did some more fine tuning, now have it where the dial settings are within 0.03% from 0 to 20v.  Also cleaned it up a bit and a fresh coat of paint.

Better than new!

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Grandchuck on January 14, 2020, 03:21:45 pm
That thing is a jewel.  Nice work!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: fastguido on January 14, 2020, 04:11:54 pm
Looks like that paint is a pretty good match. Thanks for the picture of the can.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alextwin007 on January 14, 2020, 07:07:03 pm
Seeing all of these cleaned up power supplies makes me want to try cleaning mine again.  There is some hardened glue from old stickers that I wasn't able to get off with isopropyl.  What doe people recommend to clean up the brushed aluminum faceplate of these?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on January 14, 2020, 07:59:10 pm
Seeing all of these cleaned up power supplies makes me want to try cleaning mine again.  There is some hardened glue from old stickers that I wasn't able to get off with isopropyl.  What doe people recommend to clean up the brushed aluminum faceplate of these?
I use Bestine solvent and thinner for rubber cement, which is N-Heptane. It does a very good job of removing old hardened sticker residue, but is very flammable though.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: kj7e on January 14, 2020, 08:18:50 pm
Seeing all of these cleaned up power supplies makes me want to try cleaning mine again.  There is some hardened glue from old stickers that I wasn't able to get off with isopropyl.  What doe people recommend to clean up the brushed aluminum faceplate of these?

Mine had an metal department tag on the front, popped it off with an X-acto blade then used Acetone to remove the hardened glue which worked great.  But I would be careful not to rub on any of the silkscreen.  If the surface is painted, I will try to use Goo-Gone, Acetone will remote paint quickly.  Then polished the aluminum dials and faceplate with Mothers metal polish.  Also polished the meter with Novus plastic polish.

Before and after;

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: kj7e on January 15, 2020, 03:19:29 am
Because this is the EEVBlog;
https://www.youtube.com/watch?v=JcBlhdqsGm4 (https://www.youtube.com/watch?v=JcBlhdqsGm4)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mikkkejickles on June 01, 2020, 02:34:22 pm
Just pulled a 6050C from Ebay. It needs a little work as it doesn't seem like the current control works at all.

Nice unit, It's so well built and pretty, that even though it doesn't work, I'm still glad I bought it.  :)




Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Luckbad on June 05, 2020, 05:51:08 am
Here are 3 of my functional beauties, in service daily as we speak.

The 5015D powers my audio interface, 5020 my amplifier, and 5015T my makeshift ring light for video conferences for work. I also have a TW6050 and 6150 (both working) in the closet.

Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Luckbad on July 08, 2020, 05:02:03 am
The "power on" lamp of my lovely Model 5020 has given up the ghost! Does anyone know where one can source these bulbs?
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alextwin007 on July 08, 2020, 05:31:03 pm
The "power on" lamp of my lovely Model 5020 has given up the ghost! Does anyone know where one can source these bulbs?

My oven on light died a while ago so I bought a set of neons bulbs that were on sale at electronic goldmine.  They had the plastic holder and it was a direct replacement and snapped into the case, but the plastic was orange.   
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Luckbad on July 08, 2020, 06:24:52 pm
The "power on" lamp of my lovely Model 5020 has given up the ghost! Does anyone know where one can source these bulbs?

My oven on light died a while ago so I bought a set of neons bulbs that were on sale at electronic goldmine.  They had the plastic holder and it was a direct replacement and snapped into the case, but the plastic was orange.

I have never heard of this lovely place, but my wife will hear of it when she wonders what happened to my wallet!

Are you talking about these? https://www.goldmine-elec-products.com/prodinfo.asp?number=G24950 (https://www.goldmine-elec-products.com/prodinfo.asp?number=G24950)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: alextwin007 on July 08, 2020, 06:29:12 pm
The "power on" lamp of my lovely Model 5020 has given up the ghost! Does anyone know where one can source these bulbs?

My oven on light died a while ago so I bought a set of neons bulbs that were on sale at electronic goldmine.  They had the plastic holder and it was a direct replacement and snapped into the case, but the plastic was orange.

I have never heard of this lovely place, but my wife will hear of it when she wonders what happened to my wallet!

Are you talking about these? https://www.goldmine-elec-products.com/prodinfo.asp?number=G24950 (https://www.goldmine-elec-products.com/prodinfo.asp?number=G24950)

Yeah they have some fun stuff.  Unfortunately their inventory changes a lot and they don't have the ones I got.  If you take your 5020 appart and measure the bulb inside the plastic housing, if it's the same size then it should work.  These are designed to work with mains voltage with just a resistor.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on July 19, 2020, 05:42:47 pm
I hadn't seen this site before, either. Thanks, Alex!
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on December 24, 2020, 08:40:27 am
I was looking at the history of creation of ltz1000, ended up reading interviews with Carl Nelson https://www.electronicdesign.com/technologies/analog/article/21805566/an-interview-with-analog-guru-carl-nelson (https://www.electronicdesign.com/technologies/analog/article/21805566/an-interview-with-analog-guru-carl-nelson) . Look what power supplies he used to use https://base.imgix.net/files/base/ebm/electronicdesign/image/2017/09/www_electronicdesign_com_sites_electronicdesign.com_files_Rako_Nelson_Fig1.png?auto=format&fit=max&w=1440 (https://base.imgix.net/files/base/ebm/electronicdesign/image/2017/09/www_electronicdesign_com_sites_electronicdesign.com_files_Rako_Nelson_Fig1.png?auto=format&fit=max&w=1440) . I recognize one lambda lpt-7202-fm , an hp unit or something (6284A? I'm not familiar with hp/harrison power supplies), and power designs 2005 or 2020.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: mawyatt on December 24, 2020, 03:37:55 pm
Brings back fond old memories from our labs ::)

Lambda and Power Designs were the only things that we had that wasn't Tektronix, HP or Fluke.

Carl Nelson, Bob Widlar and George Erdi were the top creative analog IC designers during their careers, they all produced many brilliant and useful ICs.

Best,
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 24, 2020, 05:45:50 pm
I recently restored an uncommon Power Designs, Inc. 6010D supply.
https://www.barbouri.com/2020/11/22/power-designs-6010d-universal-dc-source-restoration/ (https://www.barbouri.com/2020/11/22/power-designs-6010d-universal-dc-source-restoration/)
It has a maximum output is 60 Volts at 1.5 Amps, so I wonder why it wasn't given a 6015D model number?
It's a great little power supply, but there is very little documentation available for it though.
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: bitseeker on December 24, 2020, 11:50:17 pm
That's a good question. Even the original, analog-metered 6010 had the same ranges, but wasn't called 6015. :-//
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: exe on December 26, 2020, 02:15:47 pm
https://www.barbouri.com/2020/11/22/power-designs-6010d-universal-dc-source-restoration/ (https://www.barbouri.com/2020/11/22/power-designs-6010d-universal-dc-source-restoration/)

I've read the article, thanks for sharing. At it says you have some plans to upgrade the meter. I'm curious what's your plan, if I may ask? More resolution, bt-connection, dual display? :)
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on December 27, 2020, 03:49:17 am
Quote
I've read the article, thanks for sharing. At it says you have some plans to upgrade the meter. I'm curious what's your plan, if I may ask? More resolution, bt-connection, dual display? :)

Hi exe,
The display upgrade will be based on a previous upgrade to a Power Designs, Inc. 6050C display.
https://www.barbouri.com/2018/07/07/upgrading-a-power-designs-inc-6050c-with-a-4-digit-plus-mode-display/ (https://www.barbouri.com/2018/07/07/upgrading-a-power-designs-inc-6050c-with-a-4-digit-plus-mode-display/)
For the PD 6010D and some other D series units, this will provide 10 mV voltage resolution, and 1 mA current resolution upgrade on the 4 digit display.
I am currently working on the 2nd revision of the updated board, and should have all the parts in the first week of January 2021.

Image of Rev. 1.0 Board
Title: Re: POWER DESIGNS PRECISION POWER SUPPLIES
Post by: Barbouri on January 05, 2021, 08:59:36 pm
Blog post is now up for upgraded Power Designs D-series meter display.
https://www.barbouri.com/2021/01/05/new-display-boards-for-power-designs-d-series-power-supplies/ (https://www.barbouri.com/2021/01/05/new-display-boards-for-power-designs-d-series-power-supplies/)