6 Jun
2023
6 Jun
'23
3:42 a.m.
On Tue, Jun 6, 2023 at 3:42 AM John Floren via cctalk
<cctalk(a)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