Power Supply Horrors

This summer I've witnessed the death of a number of power supplies; some of them were worth sharing.

USB Hard Disk Adapter

A few months ago I've bought one of those small adapters from various hard disk bus interfaces (IDE 3.5", IDE 2.5", SATA) to USB at an electronics fair. I was happy with the way it worked, so at the next opportunity I've bought another one, this time with a different box. They both came with a reasonable looking power supply with 12V and 5V on the usual hard disk connector.

When I was using the new one for longer than usual, I heard a crack noise: I first thought that the hard disk had died (it was an old one), but after a bit of post-mortem I realized that the power supply was dead, and I've opened it expecting to change a dead capacitor or two.

This is what I found.

The supply, with the usual CE, FCC etc. marks and an unusual interior
The supply
Bad soldiering and jumper wires from component legs
Circuit back
Diodes before the transformer and other nice amenities
Circuit front

The noise I've heard is perfectly compatible with the crack in the plastic casing of Q3; what I still can't explain is why there are components rated e.g. 50V on the 220V side of the circuit, and basically how could it ever work, even for a short time.

As soon as I've checked a few values, I'll add a picture with all of the component codes I can identify.

Send a comment: unless requested otherwise I may add it, or some extract, to this page.

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