I I had a devastators board that was doing this:

The sound was fine, and the game plays as normal. The tiles all looked messed up, and there was some static corruption on top of the moving background graphics.

First, I pulled the EPROMs and found that the tile EROMs were all bad. I replaced them with new chips, freshly flashed. The image was better, but some corruption remained. After probing around the tile processors, I found that two address lines on the Konami 52109 custom chip were floating:

I ordered a replacement chip from mikesarcade.com, and some Chipquik. Chipquik is an alloy with a really low melting point (around 60C). You run it down each edge of a surface mounted chip, and it mixes with the existing solder. You can then heat up the alloy on all four edges, and it stays melted for a really long time. You can then just pick up the chip using some Blutack stuck to the end of a screw driver.

Finally, I soldered in the new chip. I used lots of liquid flux, and very little solder, and it went in easily. Any excess solder I removed with a little solder wick. Fitting the chip was much easier than I'd feared. It was my first attempt at replacing an SMD component, and it went very smoothly! The EEVBlog tutorials on youtube were really helpful (#186 and #437). I used the drag method described in the EEVBlog blog video #186.

Once the chip was replaced, it looked like this:

Finally, the total board, after fixing up the EPROM labels:

Now the game runs perfectly:

I'm starting to get the hang of these repairs now! Next I'm going to see if I can figure out how to convert a Taito Football Champ into something else.

It could be a counter, or simple inverter causing this screen offset issue. 

Look at the http://wiki.arcadeotaku.com/images/f/f7/Bubble_Bobble_-_Schematics_-_English.pdf">schematics and try to find the video ram adressing. Something must be stuck somewhere. (lucky guess, a '157 somewhere?)