Aug 012016

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.


 Posted by at 10:19 pm

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