Power Designs Inc. 5015D power supply cleanup and repair

Repair and cleanup of a Power Designs Inc. 5015D pow­er sup­ply that I pur­chased on Ebay.
This was one of the bet­ter look­ing 5015D pow­er sup­plies that I have seen on Ebay, that was not over­priced or includ­ed an over­priced ship­ping charge. The list­ings con­di­tion descrip­tion said ” ful­ly oper­a­tional and func­tions as intended”.

Power Designs Inc. 5015D front pan­el after cleanup and dis­play mod.

The unit took quite a while for the sell­er to ship but was well packed and arrived in good phys­i­cal shape.
As usu­al before I pow­ered up the unit, I per­formed some basic checks. On the out­side the exter­nal fuse was good and had the cor­rect rat­ing, and the pow­er cord ground and trans­former pri­ma­ry resis­tance checks passed. I then pulled the cov­ers and checked for loose screws and nuts, and then did a visu­al check of all the com­po­nents and wiring inside.

Power Designs Inc. 5015D main board with new fuse and capacitors

The first item I came across was a blown 4x20 mm 1.5 amp fuse with cop­per wire sol­dered on it’s end caps, and then wrapped around the fuse hold­er ter­mi­nals. The fuse is sup­posed to be a 2.5 amp slow blow 3AG, 1/4″ x 1–1/4″ unit.
With a blown inter­nal fuse I don’t see how this sup­ply was test­ed by the sell­er as being ful­ly func­tion­al, as this is the main out­put fuse.
I also noticed that there were sev­er­al signs of leak­ing elec­trolyt­ic capac­i­tor elec­trolyte sev­er­al places on the board, but no signs of bad capac­i­tors or replaced capac­i­tors on the board?
I replaced all of the elec­trolyt­ic capac­i­tors using Vishay capac­i­tors with the excep­tion of C4, which I did not have a replace­ment in stock. I did pull one lead of C4 and checked it with my Peak atlas ESR70 tester, and it was well with­in spec­i­fi­ca­tions. I also replaced C21 which is a tan­ta­lum as it had a lot of the residue around it.
Quick checks of all the diodes and pow­er tran­sis­tors all ver­i­fied good, and an extra check of the trans­former sec­ondary wind­ings because of the blown fuse, also checked OK.

Power Designs Inc 5015D cov­er removed with new components

It was now time to pow­er up the unit for the first time. I used my watts up? PRO pow­er meter attached to a vari­able trans­former to slow­ly pow­er up the unit.
At first there were no obvi­ous issues as the front pan­el dis­play lit up first at around 65 VAC, and then the neon pow­er indi­ca­tor light as I increased the line volt­age. The idle cur­rent was rea­son­able at 385 mA at full line volt­age, and no signs of over­heat­ing com­po­nents.
I set the volt­age out­put on the front pan­el to 1.00 volts and con­nect­ed my mul­ti­me­ter to the sup­ply out­put. The out­put mea­sured close to 1 volt, but there was quite a bit of drift and errat­ic volt­age changes in the tens of mil­li­volts. As I tried to increase the volt­age high­er, I could not get past 10 volts on the out­put, which is not good on a 50 volt pow­er supply.

Upgraded dis­play mod­ule and new De Young 10K poten­tiome­ter for volt­age control

I decid­ed to check the 10 turn Bourns poten­tiome­ter first, as I have had issues with them in the past.
For a 10K ohm poten­tiome­ter it only had a max­i­mum resis­tance of 2.3K which is why it could not get past 10 volts.
For a replace­ment I decid­ed on a De Young dual-stage 10K poten­tiome­ter that I dis­cussed in a pre­vi­ous Hewlett Packard 3551A post. It pro­vides the full out­put volt­age range in 1.5 turns and also a 10:1 fine adjust­ment on the same shaft.
Replacing the poten­tiome­ter solved al the volt­age out­put issues, and the sup­ply passed a full load test across it’s full out­put range.

PD 5015D Line fuse added protection

I decid­ed to add some pro­tec­tion in the way of heat shrink tub­ing around the exposed ter­mi­nals of the main line pow­er fuse on the back pan­el. This would nev­er meet todays pro­tec­tion stan­dards, but I feel just a lit­tle bet­ter that the line is pro­tect­ed from shorts at least until it is past the fuse.

PD 5015D out­put tran­sis­tors and SCR

This ver­sion of the 5015D does­n’t use the Uniply reg­u­la­tor sys­tem found in most of the oth­er C and D series sup­plies includ­ing some 5015D units with Uniply. It uses 5 MJ15015 tran­sis­tors in it’s out­put stage which all have a date code of the 52nd week of 1983. The lat­est date code in the sup­ply is the trans­former which is dat­ed June 12 1989.

PD 5015D Power tran­sis­tors, SCR, and out­put fil­ter board

This 5015D is rat­ed at 1.5 amps across it’s full out­put volt­age range of 0 to 50 volts DC. At low­er volt­ages such as 1 to 5 volts the unit dis­si­pates a sig­nif­i­cant amount of heat at it’s full cur­rent rat­ing of 1.5 amps, but is much more effi­cient at volt­ages above 12 volts.

Power Designs 5015D back pan­el and ter­mi­nal black

I also decid­ed to upgrade the front pan­el dis­play mod­ule with one of the D‑series extra dig­it res­o­lu­tion ADC dis­play boards from a pre­vi­ous post. This pow­er sup­ply uses the 200 mA full scale dis­play mod­ules, but I will be mod­i­fy­ing it to a 2.00 volt sys­tem in the near future, like I did in the Power Designs 6010D restoration.

Bottom cov­er of PD 6010D pow­er supply

I have always loved the look of the yel­low zinc chro­mate plat­ing on the brushed steel per­fo­rat­ed bot­tom cov­ers used on the Power Designs sup­plies. The above pic­ture does­n’t do it justice.

New dis­play board for D‑series dis­play mod­ules Rev. 2.4

I am cur­rent­ly wait­ing on the fab­ri­ca­tion of some new dis­play boards for the 2.000 volt range high res­o­lu­tion mod­ules, and should have an update in a few weeks.

2 Replies to “Power Designs Inc. 5015D power supply cleanup and repair”

  1. That’s indeed an inter­est­ing poten­tiome­ter. Are they still avail­able? I could­n’t find them or any­thing sim­i­lar when I searched.

Leave a Reply

Your email address will not be published. Required fields are marked *