> On 20 Aug 2017, at 16:32, Mattis Lind <mattisl...@gmail.com> wrote: > > > > söndag 20 augusti 2017 skrev Adrian Graham via cctalk <cctalk@classiccmp.org > <mailto:cctalk@classiccmp.org>>: > Hi folks, > > I think I’ve mentioned this PSU before but the question I have might be > applicable to other cheap switchers. This lump for the original Atari 520ST > is run by an NE5561N control chip with a D45H1 switching transistor. It’s > supplied by a multi-tap transformer giving 2x2 feeds of 6VAC and 14VAC with > an eventual output of 5V@3A, 12V@30mA, -12V@30mA. > > This one will run under load for around 10 minutes then the 5V rail will > gradually collapse over the next few minutes. Turn it off and leave for a > minute or so and it’s back to normal, repeat as above. > > Heat related? Try freeze spray to check if it recovers or stays working > longer.
I need to jury rig something with a breadboard to allow me to run it outside the enclosure, in normal usage it’s solder side up with the components covered. I can’t remove the transformer lump because it’s sealed in resin. They really didn’t want people to attempt to fix these things :) — Adrian/Witchy Binary Dinosaurs - Celebrating Computing History from 1972 onwards
