Double Dragon Font Problem

[DGSTUDIO]

Just acquired a Double Dragon game. Plays fine except alphanumerics are half missing and repeating. Any thoughts on this problem?

 

[ack]

I would check on IC20 on the CPU board, its the rom (21J-5) that contains all the chars. I would dump it see it matches up with whats in mame. If it does, use a logic probe to verify the address lines are all alive.

You could also try my ddragon-diag rom available here

https://github.com/jwestfall69/ddragon-diag/

But I suspect it wont help you in this case. What chars should be displayed on screen and work ram share the same ram chip so seems unlikely that would be bad if the game is running.

 

[DGSTUDIO]

Thanks for the diagnostic information. I wish I still had the game so I could find the problem. Address line sounds likely. I sold it as is a few days ago.