RE: Fluke 9100 on Tron hardware - RESULTS

Well, after about 6 hours of time invested in this
issue, I think I have an answer. Here is what I found
in getting there (the long story...feel my pain):

I originally started with a working -C000 rev SCPU
board which reported the failing RAM and ROM when
connected to the Fluke. Not being able to determine
why, I moved to a rev -E000 and found the same
results. Then I tried a rev -G000 board and this time
the Fluke successfully ran the board in RUN UUT mode
and was able to produce stable signatures. Assuming
the problem to be something Bally/Midway corrected in
the -G000 rev, I compared schematics from the two revs
to find all of the differences. I then applied all of
the relavent modifications (mostly added capacitors on
timing and control lines) to a -C000 board and tested
again. This did not solve the problem. After double
and triple checking my work, I decided to put that
board aside and try yet another -G000 board to make
sure that the success on the first one was not a fluke
(no pun intended). Well, this time, it did not work!
Whatever made it work on the first -G000 board was
obviously different or missing from this one. Then it
dawned on me... the board that I had success with had
EPROMs that I burned and all of the others had factory
EPROMs. I then decided to move the EPROMs from the
board that worked to an unmodified rev -C000 board and
that board now worked too! That's when I asked for
the datasheet for the EPROM's that I was using (Thanks
Rodger!!). It turns out that my EPROMs are 250ns and
all of the originals are Intel 2764-4's which I
believe are 400ns. For whatever reason, the slower
EPROMs work fine to run the board in game mode, but
appear to be too slow for the timing on the Fluke pod.
 In any case, it looks like the short term answer to
the problem is to get a faster set of EPROMs to test
with and then replace the originals when you get it
working. I still have some more testing to do and I'd
like to burn another set of EPROMs to double check my
results, but this is where I am right now. I hope
this will help the next time someone needs to debug an
MCR boardset.

Thanks,
-Chris

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Received on Sun May 2 10:41:19 2004