Mk2b lead channel volume rising and falling issue.

[muffinresearch]

I have a mk2b and it has a weird issue which is when on the lead channel the volume comes and goes like a volume swell and then it fades away again. Overall the rhythm channel seems fine.

Just wondering if anyone has experienced similar and could point me in the direction of a fix. I've just replaced the pre-amp valves but that made no difference.

I have the maintenance guide for the mk2b and whilst it's full of useful info there's nothing about this particular issue.

 

[Dude2Dude]

Hi there,

Have the same thing going on, but very intermittently. The volume will suddenly swell to a ridiculous level — not in a good way at all.

Have searched through this forum, and some have identified the relay as a possible source. When I get around to it, I'm going to send my IIB back to Mike B for a tun-up, and have him take a look. FWIW, when it happens, I hit standby immediately, then push in and pull out the Lead Drive pot. Seems to clear it up, at least until the next time it happens.

 

[sprocket]

Did you got it fixed fella !

 

[Dude2Dude]

If you're talking to me: No. Haven't got around to it yet.

 

[sprocket]

If you're talking to me: No. Haven't got around to it yet.

Ah ok , I thought you got it done .

 

[mesaboogie6L6]

I have a Mark III coliseum and it did the same thing, the power tubes were going bad, classic symptoms are volumes fading up and down.