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 If you ever want to (un)subscribe yourself with TTL, you can send mail to: <Majordomo@flippers.com> with the following command in the body of your email message: (un)subscribe techtoolslist or from another email account, besides xxx@yyy.com: (un)subscribe techtoolslist xxx@yyy.com