At 11:14 AM 2/17/09, you wrote:
>Did some work over the weekend.Here's what I found.The "D3" line is
>loaded down to about 2 volts.All the other Data lines are reading
>4.8- 5 volts.Pulled the PROMS, didn't make any difference.How many,
>and what I.C.s can I remove in what sequence without damaging the
>components to isolate the problem
Remove any and all ICs that have a connection to D3 one at a time
until the loading goes away. You shouldn't damage anything if you
turn off the power between each part removal. You've already tried
the EPROMs -- try removing the RAM chips, latches and buffers
connected to D3 (A29 through A34, A102 through A105, A110 through
A115 and as a last resort, try replacing the Z80.
Removing voice cards won't help, as this signal doesn't go directly
to the any voices.
-- Paul White