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theman1001 · 06-18-2009, 10:49 AM

Hi
The amp in question is a marshall jcm 900 dual reverb 4502.

The problem is the volume on channel A goes up and down by itself, and doesnt seem that loud when its on 10 on the master. I have replaced the volume pot but the problem still remains. Infact when the volume is turned down to zero you still sound out of it. When the volume drops and gets louder on its own it sometimes makes a strange buzzy sound, kind of like a bee stuck in a smarties tube.

It is only Channel A which is effected. I have put a patch cable between the send and return on the effects loop and the problem still remains. I have a multimeter so can check things if needs be.

Please help, this is driving me nuts!

06-18-2009, 10:49 AM	#1 (permalink)
theman1001 Junior Member Join Date: Feb 2009 Posts: 18	Jcm900 problems... Help needed! Hi The amp in question is a marshall jcm 900 dual reverb 4502. The problem is the volume on channel A goes up and down by itself, and doesnt seem that loud when its on 10 on the master. I have replaced the volume pot but the problem still remains. Infact when the volume is turned down to zero you still sound out of it. When the volume drops and gets louder on its own it sometimes makes a strange buzzy sound, kind of like a bee stuck in a smarties tube. It is only Channel A which is effected. I have put a patch cable between the send and return on the effects loop and the problem still remains. I have a multimeter so can check things if needs be. Please help, this is driving me nuts!