aVT 50

[Valvehead]

Picked up a cheap Marshall AVT 50 combo--had a bad speaker and r58 was burnt. Needs a new fan as well .

Its up and running but has a strange problem

On the OD channel , the tone stack = Bass works normal , but the Mid and Treble pots dont affect the tone at all

So how can the 1 work , but not the other 2 ?

R28/ 72 /73 are ok------R28 is getting to ground

mid and vol pots are getting to ground


at TR5 im seeing

D 79vdc
G 100vdc
S 79vdc

[The Dude]

Pots themselves could be bad- wiper not making connection. I'd start by checking those. Those crappy pots Marshall uses fail quite often.

Edit: ...or solder connections to the pots.

[Valvehead]

solder joints look good--went over the whole board. I suppose it could be those cheap little plastic green pots ..........thanks Dude

[Valvehead]

thanks dude----

it was the pots...amp works great