Fluke 9100/6800pod and bally mpu help needed.

From: <mail_at_nessandsteve.plus.com>
Date: Mon Oct 06 2008 - 11:55:51 EDT

Hello all,
I am hoping someone can help me out. Let me start by describing what has
lead me to this:
I receive a Bally MPU board P# r2518-35 (Star Trek) that needs
repairing.
I hook up the fluke and boot it up and get a bad clock error.
I notice someone has replaced the 74s37 with a 74LS00, so replcing it
restores the clock.
I "Run UUT" and the status LED stays on.
I check the jumpers and find that 2 are wired incorrectly so I set
them right and and I still get nothing.
After much head scratching and checking various things with a scope I
couldn't see a problem.
I replace the cpu and its socket with a spare and it starts the self
test process.
I continue on and it gets snagged on each step so replacing the
sockets on the RAM and PIA at U8 and U11 gets me to the second to last
test which failed due to a broken lead on c16. Replacing restored it
to fully working.

So the MPU board is now completetly working on the bench but if I use
my fluke it will not start the self test process.
I have tried starting the "Run UUT" from address $1000 and $5000 as I
believe this to be the address for each ROM but still nothing.

Just to be sure it was not a pod failure I tried a NOS one from the
shelf and got the same effect. (Both pods pass self test)

Can someone point out something really obvious?

Cheers
Steve

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Received on Mon Oct 6 11:56:13 2008

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