I am working on an acid damaged MPU and just as I thought I was almost done, I was doing some continuity tests and found that the +5V and ground "shorted out" (tested as continous) with my meter.
Setting to Ohms I think I get ~17 ohms between them.
This goes over most of the board (e.g. all of the "bypass" capacitors test as "continous" when testing both sides, and both sides of these capacitors test as continuous to ground.
I have spent even more time checking my work, but as this MPU's functionality is unknown I don't know if there is a problem hidden somewhere (blown chip?) or if this is just normal and it would work if I was blissfully unaware and plugged it in.
Hopefully someone knows this off the top of their head.
Otherwise, can someone please test the continuity between PINs 1J17 on the MPU board for their system 9 game? Pins 1-3 should test to ground. Pins 4-6 should be all +5v. On my MPU they all buzz as if they are connected to each other with a 17 ohm resistance.
Thank you in advance for any help with this! This drove me crazy yesterday; and I sorta gave up. Now I am at the "maybe it IS normal" phase... that could be "denial" kicking in
full board (resized).PNGschematic pic (resized).PNG