Just servicing a CS50, and it's constantly outputting a whine of about 4120Hz.
Unit came to me a bit battered as the PSU had shaken loose and trashed a few things inside.
PSU PCB had become cracked, so replaced that with a working one purchased from Synthparts.
Recapped the new PCB before I fitted it.
I've done the usual, changed the logic on the KAS board and the S/H board, replaced power decoupling caps throughout etc.
The only difference is that originally it took a minute or so to manifest... now it manifests immediately.
I can see the signal on all power lines.
Any thoughts?
B