Quote from: teemuk on August 12, 2008, 01:50:26 PM
Most likely a failed power supply capacitor.

Hm, is this anything that I can fix by myself, if so what would it cost? Or should I just take it to a tech?

My first post in this forum 

Well, this is my situation...

I bought this Marshall Valvestate S80, 40 watts (model 8240), from a friend today. I got it pretty cheap because we knew that it wasn't in it's best condition.

Anyways, directly when I turn the amp on, I get a loud buzz/hum or whatever you could call it. It's there even when all the knobs are turned off and I tried all the buttons but it won't go away.

One really wierd thing is that the buzz seems to be in the key of G (?!), so when I play some licks or whatever, in G, they sound better than it does in any other key.

My friend telled me about how it first got there. I wasn't there when it happend so I'm not entirely sure but this is what he said happened;
He just got it, but I think it was from the 90's or something, turned it on and it played really good, then he put on some reverb. But he was rehearsing with his band so I guess he took the volume all the way up. Then he took his (dist?)pedal between the amp and the guitar but when he turned it on he heard some kind of sound/pop/boom, I don't know. And after that, it sounded really wierd, kind of like it does now, I guess. But then when he switched to the clean channel it was all good.

The next day when he turned it on though, it sounded just like it did when the accident had happened the day before and with the really loud hum/buzz.

I have changed the tube to a new one and I believe that the sound is improved but with that buzz it's hard to even hear it.

But what could be the cause of this buzz? Broken/burnt ground, bad transistor or some cooked component? Well, I don't know..

I'm sorry for this wall of text, but does anyone of you have an idea what could have happend and if there's any way to make it work good again, what would it cost?

Basically, how can I get rid of the bad sound and the really loud buzz, which comes directly when I turn the amp on?

I want all of your thoughts/ides that can help me in any kind of way! Thank you very much!