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Peavey Musician Mark III Head 400GH - Help! Buzzing Problem
Hello,
Hoping someone here might have an idea. I have an (OLD) Peavey Musician Mark III Guitar Head. It's a series 400GH. Bought new in 1980 and used (very little gigging) through the mid-late 80s. Never a problem with it then. Sat on the shelf for the last 20-25 years.
I pulled it down recently to use/leave at practice. Plugged it in and it began to smoke. Brought it home, took the heat sink/circuit board out (separate install from the control panels) and vacuumed out the dust. Found a small piece of aluminum (tab off the bottom of an old soda cap) was lodged against the transformer. Removed it, reassembled and plugged in. No Smoke. Yay. Plugged in a speaker cable to speaker cab and immediately got a huge buzz, fairly high pitched and LOUD. Sounds like an open short. Not affected by volume/gain controls on front of amp. Instrument sounds DID come through over the buzz.
Tried various cables, outlets etc. No change. Know the speakers work - just played a gig with them a couple months ago. Listened closely with everything unplugged and the amp on. The amp ITSELF seems to be humming/buzzing. Not loud - ear to the box kind of thing. But it's there.
Any ideas? I'm assuming a ground short, but not sure instrument would come through cleanly over the buzz if that was the case. The previous smoke may have not been that piece of aluminum and instead was a component frying, leaving an open circuit? Box was never opened before and I didn't pull anything loose. I'm not an electronics guy, by any stretch, but if someone has a suggestion, I'll give it a go.
Any help would be appreciated.
Thanks
Nick
Hoping someone here might have an idea. I have an (OLD) Peavey Musician Mark III Guitar Head. It's a series 400GH. Bought new in 1980 and used (very little gigging) through the mid-late 80s. Never a problem with it then. Sat on the shelf for the last 20-25 years.
I pulled it down recently to use/leave at practice. Plugged it in and it began to smoke. Brought it home, took the heat sink/circuit board out (separate install from the control panels) and vacuumed out the dust. Found a small piece of aluminum (tab off the bottom of an old soda cap) was lodged against the transformer. Removed it, reassembled and plugged in. No Smoke. Yay. Plugged in a speaker cable to speaker cab and immediately got a huge buzz, fairly high pitched and LOUD. Sounds like an open short. Not affected by volume/gain controls on front of amp. Instrument sounds DID come through over the buzz.
Tried various cables, outlets etc. No change. Know the speakers work - just played a gig with them a couple months ago. Listened closely with everything unplugged and the amp on. The amp ITSELF seems to be humming/buzzing. Not loud - ear to the box kind of thing. But it's there.
Any ideas? I'm assuming a ground short, but not sure instrument would come through cleanly over the buzz if that was the case. The previous smoke may have not been that piece of aluminum and instead was a component frying, leaving an open circuit? Box was never opened before and I didn't pull anything loose. I'm not an electronics guy, by any stretch, but if someone has a suggestion, I'll give it a go.
Any help would be appreciated.
Thanks
Nick
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