Hi,
Just found this board as I was looking for AVT-50 schematics - fantastic resource and I'm hoping someone here will take pity on me
My AVT-50 combo has developed a fault and I'm wondering where to start looking... Sometimes I'll turn the amp on and it'll work fine but more and more frequently it's starting to drop out the volume on both clean and gain channels. By dropping out, I don't mean a total cut-out, more like a reduction to, say, 1/10th volume. There's no noticeable dodgy pots, turning up the volume while it's dropped out does have an effect and to some degree I can compensate but then it'll suddenly cut back in at full power.
At first I thought it was the entire amp but last night had a CD player plugged into the CD input and its volume remained constant while my guitar kept dropping out. After an hour or so of erratic behaviour the amp seemed to settle down so I'm thinking perhaps its heat related, although an hour seems a long time to settle down. The only thing I've tried is a different tube as I'd replaced the original with an Electro Harmonix and kept the old one as a spare. Both tubes show the same issue so (probably) not that...
I've also read about the R58 weakness but from the schematics it looks like that would affect the CD volume as well as the guitar so I'm guessing it's not that one
Any pointers on what I could look at / test for would be appreciated - it's still too intermittent a problem (IMHO) to pay a repair shop as I'm guessing it would take them too many hours to locate the issue and be a costly fix for something that's hopefully not major.
Just found this board as I was looking for AVT-50 schematics - fantastic resource and I'm hoping someone here will take pity on me
My AVT-50 combo has developed a fault and I'm wondering where to start looking... Sometimes I'll turn the amp on and it'll work fine but more and more frequently it's starting to drop out the volume on both clean and gain channels. By dropping out, I don't mean a total cut-out, more like a reduction to, say, 1/10th volume. There's no noticeable dodgy pots, turning up the volume while it's dropped out does have an effect and to some degree I can compensate but then it'll suddenly cut back in at full power.
At first I thought it was the entire amp but last night had a CD player plugged into the CD input and its volume remained constant while my guitar kept dropping out. After an hour or so of erratic behaviour the amp seemed to settle down so I'm thinking perhaps its heat related, although an hour seems a long time to settle down. The only thing I've tried is a different tube as I'd replaced the original with an Electro Harmonix and kept the old one as a spare. Both tubes show the same issue so (probably) not that...
I've also read about the R58 weakness but from the schematics it looks like that would affect the CD volume as well as the guitar so I'm guessing it's not that one
Any pointers on what I could look at / test for would be appreciated - it's still too intermittent a problem (IMHO) to pay a repair shop as I'm guessing it would take them too many hours to locate the issue and be a costly fix for something that's hopefully not major.
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