Build Your Own Clone Message Board

I plugged the wrong adapter into my overdrive, and it's stopped working. Surprise, surprise!

There was an awful sound through the amp as soon as I plugged it in, so I unplugged it quickly and discovered my mistake.

The adapter reads 13.8v open circuit, and is positive tip.

Plugging into the correct adapter again, the pedal power LED lights, but there's no output.

Looking at the circuit there's no evidence that any components have 'let the smoke out'.

I've scoped the circuit while powered with the correct adapter - with 50Hz hum at pin 3 of the 4558, there is nothing at pin 1.

Have I fried the IC? The datasheet has it rated to 22V max, so I'd have thought it would tolerate what I've done.

What can I do to test?
What should I be looking for?

It can handle the voltage, but not a reversed polarity, usually. That's one of the things that can fry an opamp pretty quick. If you have any spare opamps lying around, throw it in and give it a shot. That will tell you if it's the opamp or not. My bet is that it is.

Any dual opamp will work for testing: 4558, TL072, TL022, TL082, OPA2134, etc.

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Email: nick@buildyourownclone.com

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The power supply is supposed to be negative tip. Well yup, that would do it...

Will swap out the IC when I get the chance!

EDIT:
Confirmed, swapped out the opamp for a TL082 and it works again.

Now to try and source a replacement 4558...