Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: reggiepe on May 10, 2019, 08:44:12 am
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Hey all, I have a strange one on the bench this morning. I have an early 80's Champ II that had been abandoned for quite some time and I am going through it to check everything..plus since I have it open, I am going to refresh the caps in there. I pulled a pair of 12ax7's and a pair of 6V6's from a working amp, so I know that isn't the issue. So the weird thing is....I powered it up slowly on a variac and saw no visible issues. Checked the voltages and all seem to be within spec. Got no sound....strange thing is, when I turn the power switch off and the caps are draining along with the filaments cooling down, I get sound until it slowly dissipates into nothing. Did this multiple times and get the same result. Sound last for maybe 5 - 7 seconds and then fades to nothing. Any thoughts from the collective?
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I am going to refresh the caps
I wouldn't fret over the symptoms til these are new
got a scope?
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got a scope?
Nope, no scope in the arsenal yet.
I'll add too, that the sound that comes through sounds good and full all controllable by the EQ section and master volume.
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Please measure and post voltages. Especially plate and bias voltage of the 6V6s.
And just to be sure, you haven't changes any caps yet, did you?
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Please measure and post voltages. Especially plate and bias voltage of the 6V6s.
And just to be sure, you haven't changes any caps yet, did you?
Voltages are within spec of the schem voltages. No, I just opened it up to take a look and to verify all caps against the schem and to make sure there were no crispy resistors. Just placed the order for caps a few hours ago.
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Then put them in first and try again...