Re: More Omega Race notes

From: Rodger Boots <>
Date: Fri Dec 05 2008 - 04:51:49 EST wrote:
> Well, I hae spent more time in the shop on this one omega race board. Still not working.
> I did find a problem in the vector generator counters. One of the '670 was outting out a weak signal, and the counters were not counting right. This got ridd of the scrolling vectors, but now I have good garbage on the screen.
> Decided to go back to basics, and plug in the 9010a to re-test ram etc. All ram showed good, the 5101 always shows bad in this board...this might be a clue for later on.
> The vector roms are fine, food checksums (fluke-sums, that is) 8086 (funny huh?) The main program roms are suposed to check to DEC1 (oh, my, just decomissioned a VAX at work), but they don't. Crap. Kown good roms.
> Check J, okay
> Check K, okay
> Check L, okay
> Check M, crap. It's a new checksums every time I do a rom check.
> I pull the 5101, all the other roms, and all ram. Buss should be clean. Checksum it again (4 time) and a different checksum every time.
> Pull the chip (actually I tried 3 of the same chips, 1 from a know working board) and put the L chip in the M spot. Check out fine. Put the M chip in the L spot, still, multiple checksums.
> So I check the power situation, and discover there may be issues. I cannot get up to 5 volts. Fine with my 2 working boardests, but this one is dragging power down to 4.7. Don't know how I'm gonna track that down.

That should be easy enough.....replace whatever is getting hot (chip or
electrolytic capacitor or possibly a corroded area).

> Arghh....
> Mike
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Received on Fri Dec 5 04:52:11 2008

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