Super cobra repair ideas

jpx72

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Hey guys nowadays I am trying to repair a faulty Super Cobra bootleg board.
The game boots and displays video, but it's garbled.
https://youtu.be/4hW2MPN2QUs
I have reprogrammed all the eproms with original files first, but the behavor is still the same.
I can see somebody removed and socketed the NEC D8255AC-5 at position 1E.
Everything else looks ok.
Board has 5 rams at 10b-10f (Motorola MCM2125AC45). Do you think this behavior is caused by faulty ram?
Thanks for any hints!
http://imgur.com/a/ZE4uA
 
I dont think those 2125's would cause that. I'd look the board over really well for trace damage.
 
Thanks I've inspected the whole board inside out but the only suspicious place seems the socketed D8255AC-5. The socket is from 2 pieces, so definitely not original, which can mean that this chip was exchanged for some reason. I will order a new one.
 
There are 8 additional 2114-RAMs:

4 @ 1H-1K (program RAM)
4 @ 3J-3M (graphics)
 
Last edited:
Thanks I've inspected the whole board inside out but the only suspicious place seems the socketed D8255AC-5. The socket is from 2 pieces, so definitely not original, which can mean that this chip was exchanged for some reason. I will order a new one.

8255s are just interface chips for the control inputs.
 
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