More than a repair a quick fix.
I got this Dangun Feveron PCB :
The owner said that most of sprites were scrambled and I could confirm the issue upon powered up the board:
Sprites data are stored into two 42 pin 32Mbit MASK ROMs @U25-U26:
When I went to probe them I noticed a broken jumper @JP3:
Checking with a multimeter the connections of this jumper relevealed that point ‘2’ was connected to pin 32 of the two MASKs ROMs, therefore the higher address line A20.So, signal coming from point ‘3’ was not reaching this pin due this broken jumper and this caused the sprites issue.Once restored it:
all came back to normality.End of job.