POWER DESIGNS PRECISION POWER SUPPLIES

[Sparky]

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!

[radhaz]

There's a BIN Power Designs TP325 for $50 on ebay described as not working.

[Sparky]

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.

[vindoline]

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.

[skyjumper]

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!

[Vgkid]

Transistor just references it to being solid state(no vacum/electron tubes.)

[mtdoc]

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 might be useful.

[vindoline]

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!

[skyjumper]

I just picked up this one for $67 delivered:

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!

[vindoline]

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.

[vindoline]

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.

[nanofrog]

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 might be of interest.

[eas]

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.

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.

[eas]

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.

[ez24]

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

[helius]

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.

[eas]

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.

[vindoline]

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!

[eas]

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.

[robrenz]

"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.

[ez24]

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

[saturation]

2005a is an old, and simple design with a full schematic available making repair very viable.

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

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.

[idpromnut]

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.

[vindoline]

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  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! 

[vindoline]

Sorry, I botched the attached images in the last post! Here they are.