Zero Loss FX loop got blown up. Help with parts ID.

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Matthews Guitars
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Zero Loss FX loop got blown up. Help with parts ID.

Post by Matthews Guitars » Fri Sep 24, 2021 6:06 pm

Due to chipped enamel on a screen resistor, the Metro zero loss effects loop in my 2203 got toasted with screen voltage (430 volts or so...) so I took it out to repair.

Fortunately there's not much in the way of silicon devices to blow up.

I've replaced both transistors and have been checking diodes. I found a blown up 1N4148 next to one of the transistors,
and next to that there are two more diodes I intend to replace because I suspect they're damaged even though they read as diodes. But I don't know their type and haven't found a cross reference. They've got the OnSemi logo and the other markings are 24 and 28. I have not found a cross reference for this type.

So, what type of diodes are these?

Either tell me, please, or maybe provide a schematic?

If I replace them, then I'm pretty sure the loop will work again. I'll reinstall it after that's done.

The loop MAY be OK now but I want to replace those two diodes no matter what. Cheap insurance.

danman
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Re: Zero Loss FX loop got blown up. Help with parts ID.

Post by danman » Fri Sep 24, 2021 6:58 pm

The forum has been kinda slow lately so you may not get an answer here very quickly. You could probably reach out to George directly at the Metroamp web store and get a quicker reply.
https://store.metropoulos.net/pages/contact-us

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