Another Rainbow Islands PCB to repair.
This one had issues with the sprites which were broken up and seemed to be repeating, looked very much like a stuck bit on the sprite addressing;
All tiles and background graphics were fine, so I knew it was something to do with the sprite circuit.
The first thing I did was to look at the area where the sprite data is read from the two eproms. The two 74LS244 buffers checked out fine, but one of the 74LS373 Octal Latches had an output pin stuck HI (pin 9);
So I desoldered it;
I confirmed the Octal Latch was bad in an IC Tester. So I soldered in a socket and replaced with a fresh Octal Latch;
PCB sprites now restored;