Oct 282015
 

My friend Alexander sent me this original Sega Out Run PCB for a repair:

Out_Run_PCB

After adapting it to JAMMA I powered it up and I could noticed the defect :

sprites_issue

There were some dots on the screen in which I could recognize parts of sprites (lile a ghost images, I’d say).Since video board is the lower one, I could not reach with my logic probe or scope the involved circuitry made of the 315-5211 custom Sprite Generator plus sixteen 62256 SRAMs chips :

srpites_generation_circuitry

RAM test was successfully performed but didn’t cover all the chips :

RAM_ROM_test

So I went to piggyback each RAM chip and when i did it for the one @IC71, the issue was cleared:

fixed

Time to remove the chip and install socket:

62256@IC71_reworking

Obviously the desoldered chip didn’t pass the test on my programmer:

62256@IC71_failed

End of job.

 

 Posted by at 11:32 pm