Xerox 820-II troubleshooting - need advice
snhirsch at gmail.com
Fri Apr 24 16:56:48 CDT 2009
I purchased an 820-II from eBay, but the seller did a horrible packing job
and it arrived with the case completely smashed.
Incredibly enough, the CRT was not shattered and once I diassembled it and
spread things out, it nominally fires up. I get the monitor sign-on and a
beep, but no keyboard response at all.
I've already tried reseating everything on the system board and fixed a
bad solder joint on the crystal for the keyboard MPU. No luck.
I have some schematics from the web, but they are extremely fuzzy and hard
to read. Can anyone help with theory of operation for an 820 keyboard?
I gather that it's a parallel data interface, but past that I'm a bit in
I should mention that I'm running without a disk drive. The seller "lost"
it and I have the carcass of another on the way from a kind cctech group
member. Still, I would think there'd be some response to keyboard input
without the drive on line.
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