Final Fight Fixed!

Jul 1, 2019

This last weekend, after my long bike ride on Saturday, I took some time on Sunday and poked at my Final Fight arcade board to see if I could figure out its graphical issues. I FIXED IT! I originally bought this game to swap parts to fix my Strider arcade board and I knew the issue was in the B-board.

Here’s the before:

Lines!

To diagnose the issue, I had a random idea to look at the outputs of the graphics roms. I started by just grounding some output pins to see what that did to the screen. Interestingly, it produced a very similar fault to what I was seeing: that is, vertical lines running through the screen at different offsets. I found a pin that when I grounded it made no difference to the screen. We have a candidate!

Next I used a logic probe to see if that pin was outputting anything and found that it was. So data was coming out of the pin, but the signal was getting lost along the way. I followed the trace on the board and used my volt meter to test the continuity. The signal was getting lost! I soldered up some wires to fix the trace and the issue is fixed!

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Here’s the after:

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It only took me about seven years to get around to fixing this. Once I sat down to do it, it only took about an hour. I gotta say that I felt pretty COOL after fixing this, and for a fleeting moment thought about going and buying broken arcade boards on eBay to see if I could fix them, but I don’t believe I’ll be doing that!