Before I give up here is the last thing I posted concerning this issue. The first part is a little futher back with the same subject heading. If no one knows could someone one maybe point me to the right place or newsgroup that might know. I am begininng to think there is no way to actually track down a RAM error in-circuit without a lot of shotgunning.
I actually have 5 or 10 different boards like these. They sold numerous
versions. one has a work Ram error, another a video ram error, some just don't boot, some work fine. I will probably pull custom chips off
of one of the these. The ram chips I can get. I paid someone for some and of course the guy ripped me off {Hello Alan Free ( snipped-for-privacy@comcast.net ) when am I going to get my chips??} But I can find
more of them or remove them from the parts board. I have been over this board with one of those microscopes for SMD work and have checked and rechecked everything. I have re-flowed the solder on numerous chips
and checked all socketed chips. I have a few Huntron style machines with up to 64 pin clips and compared almost all of the chips against the known working board and can't find anything wrong. I have changed the main ROM with a known working one and probed the board with a logic
probe and pulsar where I knew what to expect. I have read a lot of books but I can't seem to find a method to track this problem down. I am not just wanting to get this one working, and the others but to actually learn something I can take with me to other boards. Most of these coin-op companies are out of business or no longer support these boards. We just lost another different game today because they no longer have some of the custom chips for the particular board and the board is rare, didn't come in kit form and had only one game on this particular hardware. Atari Rush the Rock. I constantly accumulate working and non working boards so that I won't have to junk a game because the board is fried. So that leaves me back at square one. This
board with the damm RAM error. Is it hopeless?
Thanks again.