On Tue, Jun 6, 2023 at 3:42 AM John Floren via cctalk <cctalk@classiccmp.org> wrote:
> It's funny that luggable power packs come up here as I'm trying to revive my > Otrona Attache... The power supply does nothing on AC input, even after a > recapping, so I thought I'd investigate the "DC Power Option" described in > the manual. Unfortunately I can't find any record that Otrona ever actually > *sold* a "DC Power Option", which would plug into an unpopulated 6-pin Molex > connector on the back of the device. Interestingly, the header inside the > power supply labeled "DC Option" is a 7-pin header, so I'm not sure which pin > was "optional" for the external connector! > > I'd just replace the power supply wholesale with a little ATX supply or > something, but the machine needs 5V, 12V, -12V, and 15V; the latter is used > to power the CRT and represents a real challenge! I've yet to find anything > that outputs all 4 levels at a reasonable price. I consider the PSU to be as much a part of the original design as any other part of the machine and like to keep them original. The schematic for the power supply is in the technical manual. It appears there's a startup supply using the mains-frequency transformer T1 as well as the SMPSU part. If that's missing then I'd suspect something around the mains input side. I assume the fuse is good! The power switch is a little odd in that it uses the triac Q1 to switch the mains, controlled by the user switch. Maybe check round that area. -tony
