Re: Fender Stage 112 SE is humming extremely loud
- From: jw022609@xxxxxxxxxxxxxxxxx
- Date: 5 Jun 2006 06:05:17 -0700
Stephen Cowell schrieb:
<jw022609@xxxxxxxxxxxxxxxxx> wrote in message
news:1149454015.877273.262790@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi folks,
I've got here a Fender Stage 112 SE transistor-based combo amplifier in
for repair from a youth center. I have some electronics experience, but
I'm not a professional in amplifier repair. The amp is humming very
bad. The clean channel is actually louder than the distorted section,
even with a shorted input. The hum level is not affected by volume
settings. Bypassing the preamp by plugging something into the power amp
input jack will cease the noise.
Can you inject a signal there and get it out, clean?
That would mean that at least the final section is OK.
What about the old trick of jumpering the pre out to
PA in with a short guitar cord... that would eliminate
those jacks as the problem.
Thank you for your advice.
Yes, I've tested it with a stand-alone preamp. The power amp works
fine, with a noise level that is acceptable for a guitar amp.
I've connected a short patch cable between the pre out and the power
amp in, but that doesn't change or improve anything.
Losing a preamp signal ground would cause this...
can you tell us if the hum is 50 or 100Hz?
The frequency is 50 Hz.
Jan
.
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