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Trouble with my Chroma Polaris

Trouble with my Chroma Polaris

2016-08-09 by lou@...

I went to use my Chroma Polaris a while back and it displayed a pattern of of lights on the LED but is other wise not functional. I can watch the data and address lines on a scope and there is activity for a short time during start-up while it boots but then everything stops dead with the exception of the oscillator.


Any ideas?


Lou

Re: [chromapolaris] Trouble with my Chroma Polaris

2016-08-09 by Bob Grieb

Maybe see if the EPROMs read correctly? Old EPROMs can sometimes lose bits here and there.
You can erase and reprogram with the same data and they will be fine. Or you could try replacing the
SRAM chip(s). Another idea would be to just pry up a little and push back down a bunch of logic chips.
Since they are socketed, it's an easy thing to do, and can sometimes restore a bad connection by wiping
the contacts a little. I guess even more drastic would be removing and reinstalling the CPU. I did help
a friend fix a Polaris that had a bad CPU. Luckily he had a "parts" board, so we just installed the CPU
from that one, as an experiment, and that fixed it. Maybe try the chip pry up then re-seat first, since it's free.
If you have an EPROM programmer, try to read the EPROMs and match them with images on the web.

Maybe Paul D will chime in with some better ideas... He's the Polaris expert.

Bob

--------------------------------------------
On Mon, 8/8/16, lou@... [chromapolaris] <chromapolaris@yahoogroups.com> wrote:

Subject: [chromapolaris] Trouble with my Chroma Polaris
To: chromapolaris@yahoogroups.com
Date: Monday, August 8, 2016, 10:09 PM