[Test-Equipment] HP 85662A Power supply problems.

[Dave]

Greetings;

Anyone on the list have experience with the power supply in this unit?

I'm having some real difficulties troubleshooting this unit.

All the supplies are present (+15,-15, HV, etc.) but all show more than 
5 volts of ripple at the test points, the same as that appearing across 
the filter capacitors.
 
They will not regulate! When I bring the unit up on a variac the 
voltages rise to their nominal values at an input voltage of app. 70 
VAC. When I increase the input the voltages keep climbing and exceed 
their rated values. Above app. 90 VAC the over voltage protector, as it 
should, shuts down the supplies,which are now above their rated values 
(i.e. +15 volts rises to 19 volts).

There was quite bit of power supply damage when I received the unit, 
primarily due to a leaking filter cap on the 140 volt supply. I believe 
all that was corrected, to the point of needed to "grind out" part of 
the PWB where the cap had leaked.

I have replaced IC's on the the A6 and A7 cards. This restored the 
missing +5.2 volt line.

The unregulated 6 volt line barely makes 2 volts. I cannot bring the 
unregulated 9 volt line up to 9 volts without the over voltage SCR 
tripping. The secondary voltages of the power transformer seem to be 
within ratings.

I do have "the other half"(B) of the system. It appears to be OK as all 
voltages and clock seem to be functional. I cannot fully test the "B" 
without the "A" connected.
Any HELP would be appreciated. I would really like to add this unit to 
my lab.

Dave, W5WP