Hello,
I'm taking a break from working on crestline ga19rvt and thought I'd work on a friends GA20. Is is a 2tone tweed with a 12" speaker and 2 vol. and 1 tone. It was found in the back room of a tv repair shop and is in good condition except that the chord was rotted and couldn't be tested. He gave it to me to re-cap and see if I could get it going. It was original inside except that the multi cap tube had been cut and another larger cap can installed. I replaced the caps with 3-10mfd x 450 volt caps and replaced a handful of out of tolerance resistors and have it working. It sounds great on the three instrument inputs but the mic input is weak. The tone knob also doesn't seem to do anything.
I don't have a schematic that matches this amp very much except for a redrawn one I found online but it is missing a few things.
To resolve the volume issue on the mic channel and the lack of tone control what would be a reasonable method to trouble shoot?
As always I'm using known good tubes.
Thanks,
Dave
I'm taking a break from working on crestline ga19rvt and thought I'd work on a friends GA20. Is is a 2tone tweed with a 12" speaker and 2 vol. and 1 tone. It was found in the back room of a tv repair shop and is in good condition except that the chord was rotted and couldn't be tested. He gave it to me to re-cap and see if I could get it going. It was original inside except that the multi cap tube had been cut and another larger cap can installed. I replaced the caps with 3-10mfd x 450 volt caps and replaced a handful of out of tolerance resistors and have it working. It sounds great on the three instrument inputs but the mic input is weak. The tone knob also doesn't seem to do anything.
I don't have a schematic that matches this amp very much except for a redrawn one I found online but it is missing a few things.
To resolve the volume issue on the mic channel and the lack of tone control what would be a reasonable method to trouble shoot?
As always I'm using known good tubes.
Thanks,
Dave
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