ASTEC 8151 PSU (TRS80, Osborne etc)

Adrian Graham witchy at
Sun Oct 23 08:02:52 CDT 2016

Hi folks,

Now that the bouncing has calmed down I've got a question about this here
triple output pretty ubiquitous power supply. This one had some burst caps
so naturally wasn't working and was probably why the machine it came out of
was taken out of use.

I've replaced all of them because why not, along with the .1uF mains
filtering cap that would also burst at some point and I still get low output
on all rails. I've tested all the major components out of circuit and
checked for shorts; in Apple ][ power supplies (also Astec, apart from the
ones that aren't) low output is mostly caused by a feedback capacitor (C7)
going out of spec, but these are all new and as close a match to the
originals I could find.

One thing I've not done is reflowed all connections so I'll do that later,
but has anyone got experience of common failure modes with these things?


Binary Dinosaurs creator/curator - the UK's biggest private home computer

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