Marshall Valvestate(VS65R) no speaker output #2

Thread Starter

HoytHoyt

Joined Nov 22, 2022
2
At risk of possibly getting deleted, this is literally the perfect for him for me to post this problem that I have. I also have a valve State 65 that has a low crackly output. The sand works perfect, as does the headphones, so the power amp section of the amplifier should be good to go. I’ve done everything in this forum (checked the Fet, no signal there) and the closest thing to a problem I could identify was R41 tests at 1.5 K as opposed to over 4K. I’m using my meter with the part in the circuit, which I found sometimes works, and sometimes doesn’t. I just wanted to see if it would make sense for me to pull the circuitboard and try to replace this resistor or if that is an acceptable range you all are on my last hope, I hope somebody’s listening.

Moderator edit: new thread created from this.
 

Thread Starter

HoytHoyt

Joined Nov 22, 2022
2
That’s what I figured… I’m trying everything in this thread, but seem to not be getting anywhere. What would the procedure to troubleshoot why the amp would be low volume and distorted (almost like a battery in your pedal was dying)? The send, and headphones both produce loud, wonderful sound when run to another amp, so per this forum the “power” circuit is good. There’s no signal going to T16, and when I try and test the speaker with the junction between R21/R24 the speaker just pops loud.

Any advice would be appreciated, I really want to get this thing working. I’m a hobbyist fixer with a few amps repaired under my belt, but they were all old and easy. I’m now a father and want to get better at this to show my daughter it’s important to fix things. Appreciate it.
 

MisterBill2

Joined Jan 23, 2018
13,754
There may be a problem with the output capacitor, C15 in the drawing.
Also, the sleeve connection on the headphone jack is not connected to "ground", and so connecting the speaker to ground is not correct.
 
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