Another Omega Race

Have an odd one (aren't they all?) I'm fixing. I had the machine in a constant test mode while working and the thing would sometimes give a fine self test, with of course the BBU ram NG (I think I have had over 10 pcb's go through here now that I have been unable to get the BBU working with a new 5101 and new socket). Sometimes though (most times) it would say the lower 4 rams fail, and the Vid roms. Sometimes it would just chirp away like it was resetting quickly with random garbage and bad vectors all over the place. Either way none of this was consistent so all sockets replaced, caps and things all over to no avail that would point to a bad flaky connection or something. All chips comparatored fine. So in frustration after 3 solid days on it I switched it over to gameplay mode just to see if maybe I would get a clue there... and it seems to work fine. It does not start up consistently 100% of the time when switched on/off (a majority of times it
 does).. but if its a black dead screen switching it off/on again usually gets it to start fine.. I have played long games on it with no corruption or anything. But if I go back to test mode, I get all the same things.   Some other odd things in test mode I get are: - every once in a while I get it flashing and chirping like its resetting and it flashes the usual rom/ram screen, but also flashes the square with the intensity bar in the middle and other self test screens with lightning vectors flashing as well. - Occasionally (more than once) I can get it where its a blank screen, but then a perfectly rendered square with a diagonal line drawn from one corner to another floats from off the top right of the screen, to off the lower left of the screen... then is blank for a few seconds, then the square very smoothly floats by again. - Sometimes I get very large letters around 4" or so in height scrolling from the right to the left very fast, then the screen resets to some other corruption over and over with other large objects like explosions..etc. - I have had a perfectly rendered ship about 4 or 5 inches high appear in the upper left of the screen, then go to other random garbage screens.   Anyone ever have something like this? At a loss as to why gameplay seems to work fine but self test so absolutely messed up.   All ram has been replaced twice over with brand new ram. 3 verified romsets swapped in and out. All custom chips swapped out through 3 sets. Anything else socketed swapped with new logic.
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Received on Thu Apr 5 13:17:08 2012