Re: Please help with Omega Race

First I would check for activity on all datalines goung to the RAMS. they alls
should be pulsing, at least the first few seconds after a reset or power up. If
you find one of them is stuck low or high, then you probably have some trouble
with a bus driver IC.

If all lines are alive (pulsate) then mve on to the address decoder. You can
check this by checking activity on the 'Chip Select' lines of the RAM chips.
They should change state al teast once during the self test. If you find one of
them stuck high or low, then the address decoder is at fault.

Hope this helps,

Mendel

MKDUD@aol.com wrote:
>
> Hello,
>
> I'm trying to repair an Omega Race board for the first time. I've
> changed almost EVERY ram, and I'm still getting errors. In test mode, I get
> no picture on the screen ecept for a diagonal line that will start from the
> LR corner and trave the whole screen to the UL corner. The error codes start
> with 5 beeps/flashes (of start led's), and cycles through 12 beeps/flashes.
> This would indicate that EVERY ram on the board was bad, but I've replaced
> them all with new ones. I was thinking of checking the address lines, but I'm
> not sure.
> To verify that the self test was working properly, I removed the rom 4
> at location J7. The self test then detected that rom 4 was bad, and then did
> it's usual routine of giving me an error on every ram on the board. I'm not
> sure what to check next. Please help if you can.
>
> Thanks,
> Michael Kelley
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Received on Wed Jun 7 15:33:22 2000