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Need help fixing Tube Screamer

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5/1/2000 11:43 AM

Need help fixing Tube Screamer

I have an exchange student from Turkey living with my family, and he bought a used Ibanez Tube Screamer yesterday at a local guitar show. It worked at the show. When he got it home he wanted to try it through my Princeton, so I said OK. He plugged a 9VAC transformer into it instead of a 9VDC. He got a hellacious hum for a while. When I got to the room and switched to an appropriate transformer, the pedal didn't work. The LED works but no sound except in bypass mode. Same story when using a battery. Can anybody give me any tips? I'm only familiar with tube stuff. Thanks!!

Keith

5/1/2000 4:54 PM
Apostilic1	You might check to see if the polarity is correct on the transformer for that pedal. It's happened to me before.

5/1/2000 11:00 PM
Frank Clarke	9VAC. The wrong polarity half the time. Hopefully replacing the diode will fix it as Gus observes. Schematic: http://www.ee.ualberta.ca/~charro/cookbook/audio/guitar/ibnzts9.gif

5/1/2000 5:02 PM
Gus	Check and/or change the Diode protection on the dc input plug most of the time the protection diode goes and "saves" the rest of the circuit.

5/2/2000 1:13 AM
Keith	Thanks for the advice. I hope Gus is right, cuz that should be an easy fix. BTW, I checked the polarity, and it's right. Thanks again! Keith

5/4/2000 1:05 AM

Well, I opened the box up and the diode was actually broken in two pieces. I fear that the protection diode was broken when he bought the thing, so applying AC may have been deadly to the other components. What likely would have been damaged by this? I can check any resistors or caps, but the IC is beyond my abilities. Should I just replace thie IC? Or are there more likely culprits?
Thanks in advance,
Keith

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