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1987x hum

1/5/2005 6:07 PM
Brad	1987x hum I'm working on a friends 50w reissue plexi, one of the power tubes died. So I replaced both tubes, checked the preamp tubes on a tube checker, and also replaced all three can caps. Now it has a really bad hum, that increases significantly when I move my hand close to the top of V2. The hum reduces a little when I touch the chassis, like a bad ground. With the volume tuned all the way down, it plays like I would expect it to at around 1 on the volume. The hum obviously gets increasingly bad when I turn up the volume. I have checked all of the ground connections on the caps I changed, retraced them to verify that I reconnected them correctly. I also verified that all soldered connections look good throughout the amp. Any ideas what this might be?

1/5/2005 6:07 PM

Brad

1987x hum

I'm working on a friends 50w reissue plexi, one of the power tubes died. So I replaced both tubes, checked the preamp tubes on a tube checker, and also replaced all three can caps. Now it has a really bad hum, that increases significantly when I move my hand close to the top of V2. The hum reduces a little when I touch the chassis, like a bad ground. With the volume tuned all the way down, it plays like I would expect it to at around 1 on the volume. The hum obviously gets increasingly bad when I turn up the volume. I have checked all of the ground connections on the caps I changed, retraced them to verify that I reconnected them correctly. I also verified that all soldered connections look good throughout the amp. Any ideas what this might be?