Cloak and Dagger pcb repair...advice needed

mikehoss1414

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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:
cd1.jpg


Pics after replacing 2 bad rams:
cd3.jpg


cd4.jpg


cd2.jpg
 
Have you checked the inputs and outputs of the LS244 at 7H?

Brian

I'll have to check again this evening, because I cannot remember off the top of my head. Since the schematics are broken up, I can't tell, what exactly is the function of this chip? I'll report back when I get home later.
 
Which outputs are stuck low? D01-D04 are the outputs for the ram. DI1-DI4 are they pulsing too?

Brian
 
i ended up pulling 7h and replacing, but no change.

all address lines and inputs are pulsing (on both 6L and 6M), but the outputs on 6L (D01-D04) are stuck low whereas the outputs on 6M are hi/low pulsing.

i think it's beyond my repair skills and test equipment at this point :(
 
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