Powertwang
12-03-2011, 06:31 PM
My amp AB763 DR has developed a bizarre problem wherein it plays great for ten minutes or so and then just has its volume drop down to zero, usually swelling back up to normal within a moment or two. The dropoff is gradual and usually takes 5-10 seconds to go from normal to 0, then swells back much more quickly. Sometimes it takes a few minutes for it to come back and sometime it does so much more quickly.
I've tried swapping out power tubes and the rectifier and, so far, have done preamp tube one, stopping to write this post and then I'll continue on down the line.
I'm pretty sure the amp's been capped in the last few years (easy enough to figure out, I know, but I haven't had time to open 'er up and see and I honestly can't remember - perhaps a sign I have too many amps) and when it's at volume it sounds fantastic.
Any guesses as to what's the issue?
Thanks,
John
I've tried swapping out power tubes and the rectifier and, so far, have done preamp tube one, stopping to write this post and then I'll continue on down the line.
I'm pretty sure the amp's been capped in the last few years (easy enough to figure out, I know, but I haven't had time to open 'er up and see and I honestly can't remember - perhaps a sign I have too many amps) and when it's at volume it sounds fantastic.
Any guesses as to what's the issue?
Thanks,
John