Ok, Took the Base Chip, Game Chips, PXL Chips and the CG Chips from the 3902 CPU board that was having the same problem as yours and I installed them in a CPU board that was good. The machine booted up just fine. So I took the all chips out of the good CPU board and put them in the bad CPU board again. pulled the memory out of the good CPU board and installed them in the bad CPU board. The bad CPU board would not boot up with the good memory in it. To me it looks like all the chips are good and the memory is also good. My best guess is there is a issue with the CPU board. There are a lot of members on this site with way knowledge that me on this stuff. I am sure they will get your issue taken care of. Best of luck!