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This Super 60 came in with non working reverb. I have the amp on the bench hooked to an exteral speaker. The feedback starts a second or two after I take it off standby and breaks in to a scream both volume controls are at zero. The only way to get the amp to play is with the reverb unplugged. The old pan doesn't work. The new pan 8eb2c1b makes the problem worse. Any ideas, I'm lost at the moment....Hope I can get this weirdo fixed....
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Isolate the problem. Does turning the reverb control to zero stop the noise? Does moving the pan outside the cab diminish the noise?Education is what you're left with after you have forgotten what you have learned. -
The amp is out of its cab and on my bench.... Reverb knob is at zero.... The pan is away from the speaker on my bench. Volume control doesn't stop it.....Comment
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Seeing that the volume control is way before the reverb circuit, that cuts it down some.
When the amp is 'howling', put a plug in the Power Amp In jack.
If it is strictly a preamp issue, that should kill it.
I would start at the power supply.
Especially the opamp supply & the bias supply.
Check for Vac ripple.
There should be none.
Next up would be the opamps themselves. (U101 & U102)
Find out if any of the output pins are doing the howling thing.
Super_60All.pdfComment
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Non-working reverb and howling reverb may be 2 different things.
Was it howling for the owner (unusable), or did that just start with the bench set-up?Originally posted by Enzo
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The owner brought it in because the reverb wasn't working. It only screams when the new tank is plugged in. With the tank UNPLUGGED the volume controls work normal, but with a lot of hum. It acts like the reverb is at full gain. I can hear the echo of the pan when I take it off standby then the feedback starts. The reverb pot has no control/change....Anyway, no howling till plugged in the new pan . The old pan is shot. I think I have a Traynor pan (high imp.) and see what happens and see if the reverb pot is grounded....Comment
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So is the reverb control defective? Or missing its ground connection?Education is what you're left with after you have forgotten what you have learned.Comment
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GOT IT!.......A grd. jumper wire from the main circuit board to the circuit board that has all the controls mounted to it had broke off. Fender uses some cheap brittle stranded wire that can't take flexing. I used my ohm meter to check the grd on the reverb pot, found NO grd. So looked around and found the broken wire. That brought everything back to normal.... This is my 3rd repair in a row for bad grounds.... This one got my goat! Cheers to all !!!Comment
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Why is it that the 'simplest' things always trip us up?
Murphy.
The Gremlin.Comment
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