Hi all,

I've a poorly IBM 5162. It has been fine for 18 months or so since I got it, with usage on and off. I even spinrite'd and recovered the ropey MFM HDD that has been solid since.
I was using it to image some floppies, and it was powered on, booted and idle at a dos prompt, when I came back to it the screen was blank, and it seemed to be locked up - no keyboard LEDs worked, etc.
Since then, it won't boot - no monitor output, etc. An ISA post card show it stuck at '21'. Behaviour visible here:
https://cdn.discordapp.com/attachments/110342 … 3515045b6102c9&

Minuszerodegrees, https://minuszerodegrees.net/5162/post_errors … _post_codes.htm suggests 21 is the point at which an MDA/CGA card would be initialised.
This machine only has a VGA card (always has when in my possession) , and I've tested it in another machine, and it still works. I've also tested another known good card in here. Anyhow, my understanding is that a VGA card with its own bios would initialise itself later on in proceedings (POST 23?).

Anyone seen anything similar? I've removed all non essential ISA cards (including the disk controller) reseated some ICs, checked nothing loose. POST card suggests voltages are fine, so whilst I could try another PSU I suspect that won't change things.
Should I perhaps get myself some eproms and try the landmark diagrom (I understand this needs cga 😒)? Any other suggestions would be appreciated before I contemplate buying an osciloscope and having a poke around not really knowing what I'm doing.

Thanks as always.