Marhsall Power Amp Problem (9100)

[Muttley]

My 9100 (50W/50W valve power amp) has started gving me some problems. One channel works fine, but the other side is completely silent until I crank the volume way up at which point it kicks into life and I scare the living bejesus out of anyone in the vicinity (including myself sometimes).

Any ideas what could be causing this, and if it's easy to fix? I'd rather not send it off for repair if possible, as I'd probably have to take out another mortgage to pay the shipping it's so damn heavy.

Cheers

Muttley

 

[Tachy]

I have the same problem with my el 34 100+100..one channel work fine and the other channel don't give me sounds..
If you put you stanby on the amp give you a little sound or nothing??

 

[Muttley]

Nope. But every time if I crank the volume on the channel it eventually kicks in.

 

[Tachy]

I don't know what is, but the only thing that I can tell you is that.. don't put your hand in it if you are not shure that what are you doing...exume for my bad lenguage.

 

[cobhc]

Could be a loose powertube or something, i'd unplug it, leave it for 30mins or so, have a look inside at the tubes, just sort it give it a little check see if anything looks like it's not plugged in properly, and i wouldn't delve much further before taking it to a tech.

 

[2dark]

I have the same problem at home but with the amp from my stereo.
But I'm too lazy to fix it, because it's "just" a wrecked capacitor in
the output amplifier section and I'm not at home that often so I don't care
that much and I like to annoy my neighbours with loud metal

In your case it could also be the volume potentiometer itself. If you know
what you're doing you could check that first (cleaning and check it with an
Ohm-Meter).

But taking it into service would still be better.

 

[Muttley]

Thanks for the pointers. I think I may need to get a pro to look at it, I'm not too hot on electronics.

 

[Muttley]

Just a bump to say it's all sorted now. Ended up being some dodgy soldering at the power stage of one channel. As soon as that was redone the problem went away.

Muttley

 

[Mr. Brokenamp]

Dude those are the WORST designed tube power amps ever. They are notorious for breaking. Actually be careful with all the 90's Marshall stuff they had lots of bad solder joints that caused stuff like what you're describing.
I read about this then disregarded it , then I got a 9200 and bam, solder joint went on a transistor and then that led to destroying the output transformer.