Traynor YCV40 low B+

[mokomon]

Have a Traynor YCV40 , stopped working , tubes all test good , B+ low. Replaced Q8,Q12,D13,U3 , R100 tests good . Still doesnt have much B+ , 38v. 430v at D of Q8 ,38v at G & S of Q8. I tested for B+ at WC11, with output transformer dissconnected and power tubes out. Any suggestions ?

[BobK]

I would next check the operation of the 4N35 optocoupler.

Is it doing anything at all when you flip the standby switch to operate mode?

I don't know about those parts failing in general, but you've got me stumped so far, so I'd start going back to basic operation of.... everything?

[mokomon]

Problem solved , R50 was open