POWER DESIGNS PRECISION POWER SUPPLIES

[bitseeker]

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.

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).

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.

[SharpEars]

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.

[Vgkid]

Does it deal with the range switchover on the transformer?

[SharpEars]

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

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:

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).

[dom0]

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.

[bitseeker]

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.

[boborjan]

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

[motocoder]

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.

[boborjan]

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.

[motocoder]

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.

[iampoor]

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
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  )

[motocoder]

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
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  )

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.

[bitseeker]

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.

[bitseeker]

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.

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+

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?

[motocoder]

To add a digital readout to a vintage analog power supply, connect a free cheapie multimeter from Harbor Freight.

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.

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+

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
10-turn 1K potentiometer (Bournes): 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.

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?

• I prefer the voltage adjustment on the HP. The pushwheel switches are a heck of a lot easier to work than those concentric dials on the PD. OTOH, those thumbwheel switches are a potential point of failure and refurbishing them is a bit more work than spraying contact cleaner on the contacts of the PD rotary switch.
  
• There is no oven in the HP. The PD ovens are notorious for going out, plus I'm always feeling like I need to wait for the thing to warm up and turn off the oven light (but of course, you don't). Honestly, that oven circuit in the PD makes me a little nervous. This is why when I repaired mine, I used the lower secondary voltage instead of mains as in the original circuit. I've seen and heard of enough PD supplies with dead heaters to know that this part of the supply is a bad design.
• The HP current limiting circuit is a little better. You can actually use it as a reasonable constant current source if you want. The PD circuit is more just a current limiter and is not as stable in CC mode.
• The series regulator circuit in the HP handles the low/high range automatically. In the PD, there is a switch you have to flip.
• The HP 6114A/6115A supplies have an IEC connector in the back for the power cord. On my PD2005, the power cord is hard-wired in, and there isn't enough space for a mod to add the IEC socket.
• I created a template for the front panel on the HP supplies, so if that needs refurbishing, I can easily print out a vinyl sticker for that. OTOH, the PD supply front panel is pretty robust and less likely to be messed up from people trying to scrape calibration stickers off it.

[bitseeker]

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.

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.

[motocoder]

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.

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.

[iampoor]

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. 
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!

[timb]

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.

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.

[nanofrog]

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.

[motocoder]

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.

[motocoder]

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.

[timb]

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.

[motocoder]

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/

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.

[PaulAm]

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.