Hi
Still having issues with this CS50 PSU.
I've got a horrible high pitched whine all over everything. If I turn the amps off, I can actually hear this noise emanating from the PSU.
If I put a probe on the lines, I've got oscillation on both the + and -15V lines. Much worse on the -15V line.
I've recapped it, changed all the transistors, and diodes (Apart from the rectifiers)
Changed the 4458, but no change.
What's really odd is that if I touch the anode of the -15V zener (Opamp supply) with a scope probe, it collapses the Opamp supply.
Also... If I remove voice cards 3 and 4 from the rack and the problem goes away... even though they're still connected to the power.
Any incite, or suggestions? most welcome... I've got to get this thing sorted in a couple of weeks, so a client can use it on a session. :-s
