Help with Pro JR 90s

Travis

Travis

Active member
Hi!

I have a Fender P JR of 90s, when I turn it on sounds weird and buzzing but 15 minutes later it´s sound perfect.

Also I must wait to start hearing the amp like 2-3 minutes since turn it on.


Some recommendation? All filter caps read around 350v but C18 is around 240v.

I try new valves and the problem still there.

Thanks.
 
I check the circuit and I changue filter caps (one was out of Range) and try new valves and the problem still there.

Also I replace C13, C14, C11 and C10.

Some ideas or Help? Thanks...
 
So there is no sound for 2-3 minutes after turning the amp on? That sounds like a problem with the filaments. What voltage are you getting at pins 4-5 and 9 on the preamp sockets. Both at start-up and after the amp has warmed up? Maybe it's a cold joint on one of the filament connections which makes a better connection once it's warmed up?
 
If it has PCB mounted tube sockets, reflow the solder at every pin on every socket. It is a very common failure point. And it could be the sockets themselves. The old Peavey Classic 30s from the same era will get metal fatigue in the leads from the socket to the PCB and break over time. They're easy enough to replace though.
 
Right now the amp sound when I turn It on. But it's distorted at any level.

I Will check volts on 4/5 and 9
 
are any of the tubes loose on the board if you try gently to rock them from side to side? that would suggest one or more loose pins in a socket that might not be making a good connection. the long warm-up could literally be that -- a loose connection or contact on the heater connections. make sure to take precautions when working on the board -- not just turned off and unplugged, but making sure the large caps are discharged. you should be able to find some safety guides on the internet.
 
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