A quick fix for a PCB that seems to develop always same issue judging from my experience and other repair logs.Received this Snow Bros for a repair:
It was playing fine but some sprites suffered from flickering (it’s hard for my camera to capture this, see from second 5 of below video) :
Maybe you can understand better from this picture provided me by the PCB owner:
The sprites are generated by the Pandora custom chip which read data from a MASK ROM and write them to four 4464 (64K x 4bits DRAMs) :
When I went to probe these dynamic RAMs with my scope all was good except one data line (D2, pin 3) of the one @IC24, signal was weak and stuck high compared to an healty one:
Confident I removed the chip which failed when tested out-of-circuit:
Installed a socket for a fresh chip:
and tested again the board:
No more sprites flickering and game 100% fixed.
Sorry, the comment form is closed at this time.