mikehoss1414
Well-known member
I picked this up recently...when i got it, it looked like the first pic and would reset once i tried to start a game. I'm very new to pcb repair, and really feel overwhelmed most of the time, but i'm slowly trying to learn. so far i've gotten rid of the lines across the screen (replaced a bad 4116 on slave board) and am able to start and play a game (replaced 6116 ram on main board), however, i cannot figure out the motion ram error (loc 6L).
I've replaced the original 2101-a ram in 6L and 6M with working am93422 chips, replaced the socket at 6L, and verified all traces. The only testing tools i have are a dmm and logic probe. All address lines appear to be active, however, the data out lines on 6L are stuck low (with a steady pulse) whereas the data out lines on 6M light up both my high/low lights and pulse randomly. The data input lines appear to be acting the same on both ram chips...what could cause the data out lines to be stuck on 6L, but not 6M??? I've swapped the ram and there is no difference. I'm very confused at this point. I am using a jamma adapter if that makes any difference???
Any help / advice would be greatly appreciated...i'd really like to get this one working without having to send it out. Thanks!
When i received the board:
Pics after replacing 2 bad rams:
I've replaced the original 2101-a ram in 6L and 6M with working am93422 chips, replaced the socket at 6L, and verified all traces. The only testing tools i have are a dmm and logic probe. All address lines appear to be active, however, the data out lines on 6L are stuck low (with a steady pulse) whereas the data out lines on 6M light up both my high/low lights and pulse randomly. The data input lines appear to be acting the same on both ram chips...what could cause the data out lines to be stuck on 6L, but not 6M??? I've swapped the ram and there is no difference. I'm very confused at this point. I am using a jamma adapter if that makes any difference???
Any help / advice would be greatly appreciated...i'd really like to get this one working without having to send it out. Thanks!
When i received the board:
Pics after replacing 2 bad rams:
