Saturday, July 20, 2019

Amiga 500 power supply repair

I bought a cheap Amiga 500 as non functioning. I knew that the power supply was non-functioning, so I started there.

Amiga 500 PSU
The inside looked OK, but there where several signs of somebody tampering with it.
The bottom part of the PCB had some funny looking solderings with a lot of gunky-looking flux residue.

Bottom side of PSU PCB. Some gunky looking flux residue can be seen to the bottom right, top right and top left.
The board is marked 871, 6L78, A 500.
When I removed the strange looking solder I discovered that one of the pads to the transformer didn't have a connection at all! Maybe it was loose and I sucked it into the solder sucker.

Anyway, I soldered some wire to the transformer and touched up the bad looking solder joints, and the PSU worked nicely after that.

Repaired transformer connection behind the fuse

Transformer pads with solder removed. Pad with no connection to it to the right of the large mounting hole in the middle.

I made a note of the electrolytic capacitors on the board, so that I can order new ones and recap it.

No capsC(uF)U(V)diam (mm)

When I have recapped the PSU, I will properly clean off all the old flux.

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