HP 6237B power supply issue

[belzrebuth]

This one come with damage on the both front meters so capacitors C11 and C21 were also broken from the PCB.
Most probable cause was front impact and vibration.
The issue is that when I connect COM to Ground -20V rail goes short circuit!
Only thing I did was powering it on with capacitors C21 and C11 detached from the PCB since it wasn't immediately obvious that they were off.
Fixed tracking is fine and current capability also seems fine.
D21 goes short circuit when I connect common to gnd.
edit :Forgot to attach the SM and partial schematic!
https://xdevs.com/doc/HP_Agilent_Keysight/HP%206236B%2C%206237B%20Operating%20%26%20Service.pdf

[belzrebuth]

C17 was shorted to GND thru bent grounded chassis so essentially -20V rail was referenced to GND.
Bending back the chassis a bit and cutting the led of the cap a bit shorter fixed the thing.

[Alex_Baker]

Sweet!

 I have had many repairs like that, ends up being something completely benign. What's important is that you got there in the end.

[belzrebuth]

I wish I had a couple of those meter holders as well
At least it's working fine now!

[coromonadalix]

this psu  positive is common to the ground,  they use this trick  to mimick / generate the negative voltage,  instead of having true negative regulators

i dont see the other psu sections,  but you seem to have a floating regulator   .... and they take  a 20v from the positive one to go at u2 

awwwww man and the positive one  regulate by the ground   


way to complicate things here  pfffffff


this is not a standard way to make a psu, it will work as designed,  but you have to be careful how you connect your things on this psu

dont forget it is a tracking power supply,  it mean  the +20volts will move / vary at the same time as the -20volts in "tracking mode"

on witch ground you connect the COM ??  where ?