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Marshall 2204 JMP Hum


 
4/10/2000 3:56 PM
Seth Marshall 2204 JMP Hum
I have a 1979 JMP that has a pretty loud hum when the mv is turned way up. I replaced the power supply capacitors and it still hums. Anything I should look for?  
 
TIA
 
4/10/2000 4:18 PM
Trace
email

quote:
"I have a 1979 JMP that has a pretty loud hum when the mv is turned way up. I replaced the power supply capacitors and it still hums. Anything I should look for?"
 
 
A certain amount of hum is normal when the amp is dimed or set "wide open." Does it hum louder when ou have a cable plugged into the input jack verses when you do not have anything plugged into the input jack?  
 
Trace
 
4/13/2000 4:45 AM
Richie
Those jacks are usually the first thing  
that causes problems. And maybe just moving some  
wires in the circut away from others  
would help. And shield the input  
to the tube. {~}==::: Richie
 
4/14/2000 4:17 AM
james price
email

Check and make sure the bridge rectifier ground isn`t grounded to signal ground at front of amp where the pots are. My 74 Super lead was like that and caused hum similar to yours!!  
Groovtubin@aol.com
 
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