Keeps us posted Mike ! I wanna know the outcome :-)
Yep thanks to Hakan for the great info !
I do have a 2232 scope with the same problem and similar SMPS design as far as I understand. All the component designators I read above surely ring a bell, at the very least...
Luckily for me, in my case, that ear breaking screaming sound progressively goes away after 5 to 10 minutes as the scope warms up. Still, would love to eliminate this noise completely if at all possible.
A few months ago the SMPS blew and I had to replace half of it. Had to replace T906 because it was burnt/open circuit when the FET died and dumped the mains into it (and the PWM chip and other stuff as well), poor little thing. Anyway, just for the record, I replaced T906 with one that had the white gunk in the middle, and it still does that hight pitched horrible noise, so this might not be a magical stick.
Anyway, watching this thread with great interest, so keep us informed of your progress Mike ! :-)