I have an old 0-100V (0.2A) HP power supply (HP 6116A), which is broken. The output is always 0.6V (when on). Nothing is obviously burned or exploded inside.
The problem started when one of the people in my lab connected a capacitor backwards across the supply's output, giving it a large negative voltage spike.
Any ideas on what could be the problem? The supply has a transformer and several largeish capacitors. However, the inner circuit is pretty complicated. My guess is something near the output is broken, but what could it be?
First, I would get an Operating and Service Manual for the 6116A off eBay or one of the vendors that specialize in manuals for obsolete test equipment. These are usually $30 or so. In addition to schematics it will have circuit descriptions and parts lists which will make your troubleshooting much easier. HP equipment of this vintage shipped with this manual but unfortunately lots of them have been misplaced over the years.
Second, HP supplies typically have lots of internal power and bias supply voltages. One or more of those being out of spec can result in lots of strange behavior at the main outputs. Unfortunately without a manual you don't know where to probe or what is OK.
Third, I don't know specifically about the 6116A, but lots of HP supplies have output over voltage protection that is implemented using a comparitor and a SCR which crowbars the output to near zero and is reset by power cycling the supply. I know the later model 6114A and 6115A have that type of protection. If you managed to put enough voltage and current back into the supply, you might have zapped the comparitor so the the output is always shorted by the SCR.
Fourth, if it isn't the over voltage protection at the output, then you might have zapped the output voltage or current sensing amps.
Hope this helps and let us know how your repair turns out.
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