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PostPosted: Apr Sat 04, 2020 9:44 am 

Joined: Jan Sat 27, 2018 4:12 am
Posts: 57
Someone years ago gave me this power supply and it worked OK, the voltage control knob was intermittent and the current with no load showed it was drawing .28A
With some spare time lately I decided to tear it apart and see if I could find the problems (it was great to leave in the garage to do car work).
After looking at it, I ordered an old manual and started comparing the schematic to the PC board. The PC board said it was model B1, and the schematic showed 3 extra transistor's that were not on the PC board . Could the PC board be an early version and it was upgraded and the updated schematic didn't match the PC board? The cooling fan motor isn't working, think the armature is damaged, it spins free but doesn't move when voltage is applied.

I cleaned it all up, repainted the case, cleaned all the components, drew an updated schematic, took pictures of everything as I tore it down (never know what you forget when reassembling it months later.

Does anyone have one of these? It's mfg date is around 1963 I'm guessing.

What am I missing? Wrong schematic? Outdated board?

PostPosted: Apr Sat 04, 2020 1:26 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5975
Location: Montvale NJ, 07645
Large power supplies usually have one (or several) transistors mounted on the case for heat dissipation. I can't find a schematic online for it, heck, I can't even find a picture of one. It must be a fairly uncommon unit. Harrison made a lot of power supplies for HP, excellent units, but some of them get crazy complicated. I have services a bunch of the later HP/Harrison power supplies.

I don't know what is going on in your case, but post some pictures and the schematic and maybe someone can help identify the issue.

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