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Mission MS 200 Schematics / Repair pointers (self.askelectronics)

submitted 11 months ago by boojumliussnark to c/[email protected]

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I have a Mission MS 200 Subwoofer where the power supply has stopped working. I was quite happy with it, and would like to try to fix it, also I don't have the money for another. I have taken it apart and have narrowed the fault down to the PSU. I have visually inspected the solderings and components, and nothing obvious is wrong. I am not good enough to be able to reverse engineer the board, and was hoping there might be someone here with access to a schematic? Failing that, any pointers on where to maybe do some in-circuit measurements to narrow down which part(s) might be broken, would be very highly appreciated!

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[–] czardestructo 4 points 11 months ago (5 children)

The initial debugging you did, how did you root cause to the PSU? Your debugging aside I would check the fuse and MOV first. Did you have any bad weather recently? Lightning will take out your fuse and MOV and they're an easy fix. Google what a Metal Oxide Varistor looks like. Next I would check for any damaged or blackened parts, then check the capacitors for bulging and capacitence values. Anything after that will get heavy on the EE side of things.

[–] boojumliussnark 1 points 11 months ago* (last edited 11 months ago)

I am guessing the MOV is the component marked MOV on the board, its markings are: TVR 07471. Can I test this "in-circuit, or must I de-solder it to test it?

In-Circuit I measure around 470kohm

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