The client brought me some documentation describing troubleshooting.
It says the control modules can function as a voltage amplifier without the output modules, provided there is no load. Relevant page attached.
I've removed the short between Q10-11.
Power modules removed. No load. Plugged directly into the wall. No DBT or variac.
30VDC on the output, and it goes up to 50V when I short the RCA input jack.
Tried changing all the small diodes, even though I'd checked them before. No change.
Tried changing C30/31 since the document said high offset could be caused by leakage here. It also said C29/32 could be at fault but I don't have any 100pf caps on hand.
The decoupling capacitors, 0.1uF between the power rails and ground on the control module I added at the suggestion of an earlier post are still in place.
As requested in the above post, Q2/3 base voltages are 30V.
~1.2V across R115/120 (47ohm)
Q10 base: 30V
Q10 emitter: 29.3V
It says the control modules can function as a voltage amplifier without the output modules, provided there is no load. Relevant page attached.
I've removed the short between Q10-11.
Power modules removed. No load. Plugged directly into the wall. No DBT or variac.
30VDC on the output, and it goes up to 50V when I short the RCA input jack.
Tried changing all the small diodes, even though I'd checked them before. No change.
Tried changing C30/31 since the document said high offset could be caused by leakage here. It also said C29/32 could be at fault but I don't have any 100pf caps on hand.
The decoupling capacitors, 0.1uF between the power rails and ground on the control module I added at the suggestion of an earlier post are still in place.
As requested in the above post, Q2/3 base voltages are 30V.
~1.2V across R115/120 (47ohm)
Q10 base: 30V
Q10 emitter: 29.3V