TAD Cabal arcade pcb repair
Like the Legend of Kage and Tiger Road repairs all sprites had every other scanline missing suggesting a failure in double buffered sprite line RAM.
The entire top board is for sprite processing and contains 12 ram chips (the tilemap, palette and main RAM is all on the bottom board). The bad chip was found by piggy backing a known good RAM chip on top of each RAM until the problem went away.
Trackball to joystick mod was also built and installed thanks to the work at http://elgensrepairs.blogspot.co.uk/search/label/TAD