Author Topic: POWER DESIGNS PRECISION POWER SUPPLIES  (Read 224255 times)

0 Members and 1 Guest are viewing this topic.

Offline mtdoc

  • Super Contributor
  • ***
  • Posts: 3576
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #850 on: July 13, 2018, 01:38:31 pm »
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. 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.



« Last Edit: August 03, 2018, 04:51:33 am by mtdoc »
 
The following users thanked this post: Barbouri

Offline nanofrog

  • Super Contributor
  • ***
  • Posts: 5448
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #851 on: July 13, 2018, 01:58:21 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).
 
The following users thanked this post: mtdoc

Offline mtdoc

  • Super Contributor
  • ***
  • Posts: 3576
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #852 on: July 13, 2018, 02:35:46 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.
« Last Edit: July 13, 2018, 02:37:21 pm by mtdoc »
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7158
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #853 on: July 13, 2018, 03:10:20 pm »
Unfortunately, I don't have a better schematic. Perhaps someone did something funky with tracking since source A was affected.
Life is better under the TEA. ♪♩♫ Under the TEA. ♩♫
 

Offline nanofrog

  • Super Contributor
  • ***
  • Posts: 5448
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #854 on: July 14, 2018, 09:44:21 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).

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.
 

Offline JonM

  • Supporter
  • ****
  • Posts: 142
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #855 on: July 17, 2018, 01:31:46 am »
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.
 

Offline KrudyZ

  • Regular Contributor
  • *
  • Posts: 142
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #856 on: July 17, 2018, 03:41:07 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.
 

Offline JonM

  • Supporter
  • ****
  • Posts: 142
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #857 on: July 17, 2018, 12:25:06 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.

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.

 

Offline nanofrog

  • Super Contributor
  • ***
  • Posts: 5448
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #858 on: July 18, 2018, 01:02:09 am »
The first task is to get that 0.1 v position to move reasonably.
I recommend going with Caig Deoxit products. It's not cheap, but works extremely well. The K-2C sampler kit 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.
 

Offline mtdoc

  • Super Contributor
  • ***
  • Posts: 3576
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #859 on: July 20, 2018, 12:49:04 pm »
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.

 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7158
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #860 on: July 20, 2018, 02:15:45 pm »
That's a sneaky fault. Good sleuthing, mtdoc.
Life is better under the TEA. ♪♩♫ Under the TEA. ♩♫
 
The following users thanked this post: mtdoc

Offline exe

  • Supporter
  • ****
  • Posts: 1068
  • Country: nl
  • self-educated hobbyist
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #861 on: July 22, 2018, 07:29:08 pm »
2mtdoc: are these wires, soldering and cable ties original? It all looks very well and tidy for such an old piece of equipment.
 

Offline mtdoc

  • Super Contributor
  • ***
  • Posts: 3576
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #862 on: July 23, 2018, 01:52:33 am »
Yep, all orginal AFAIK. The PD supplies are like that.
 

Offline nanofrog

  • Super Contributor
  • ***
  • Posts: 5448
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #863 on: July 23, 2018, 02:10:15 am »
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?
 

Offline Barbouri

  • Contributor
  • Posts: 33
  • Country: us
    • Barbouri's Electronics Projects
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #864 on: July 23, 2018, 02:12:40 am »
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.
 
The following users thanked this post: kj7e

Offline mtdoc

  • Super Contributor
  • ***
  • Posts: 3576
  • Country: us
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #865 on: July 23, 2018, 03:04:13 am »
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.
 

Offline exe

  • Supporter
  • ****
  • Posts: 1068
  • Country: nl
  • self-educated hobbyist
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #866 on: April 15, 2019, 04:58:56 am »
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/ . 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?
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7158
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #867 on: April 15, 2019, 08:03:37 am »
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.
« Last Edit: April 15, 2019, 08:12:18 am by bitseeker »
Life is better under the TEA. ♪♩♫ Under the TEA. ♩♫
 
The following users thanked this post: exe

Offline Barbouri

  • Contributor
  • Posts: 33
  • Country: us
    • Barbouri's Electronics Projects
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #868 on: April 15, 2019, 10:19:43 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.
 
The following users thanked this post: exe

Offline exe

  • Supporter
  • ****
  • Posts: 1068
  • Country: nl
  • self-educated hobbyist
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #869 on: April 15, 2019, 07:20:58 pm »
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.
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7158
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Reply #870 on: April 16, 2019, 04:50:26 am »
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.
« Last Edit: April 16, 2019, 04:52:05 am by bitseeker »
Life is better under the TEA. ♪♩♫ Under the TEA. ♩♫
 
The following users thanked this post: exe


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf