May 012014

Another of muddymusic’s boards here.
This one had graphics issues around the sprites.

Looking as the MAME source you can see that the sprites are held in the MASKROMs marked UA2-3, 4, 5 & 6.
Probing all the pins on these chips revealed that pin 25 on three of these chips was floating. These are 23C2001 MASKROM’s which a datasheet is easily available for.

The last ROM had a signal at this pin and the other three are all linked off it so there is a break somewhere on this trace. I patched this line and tested.
Almost there but still a little issue around the text.

A bit more probing found that pin 11 (A1) of ROM UA2-4 was also missing. Again I patched this from the adjacent ROM and tested.

All appears to be working now.

 Posted by at 8:11 pm