Well, as part of progress on my Simpsons restoration I knew I'd have to deal with player 2's coin input being stuck closed according to the test screen. I know this is a board failure because it does this in any cabinet or test rig. JoshBrown80 and I took a look at the schematics tonight and we are 99% certain we have narrowed it down to the SN74LS257AN chip which handles the coin inputs. Pin 6 is player 2's coin and when I test from that pin to ground, it's shorted. No other pins on that chip short to ground except ground of course so it seems like this chip has to be the problem. I have a junk 6 player X-Men pcb that has a similar chip SN74LS257BN. The difference being the Simpsons chip has an A and the X-Men board has a B as the second to last letter. Can anyone tell me if these are compatible or if I need to find the exact one as on Simpsons. If anyone also cares to verify that Josh and I are correct with our diagnosis that would be great too.
Here's the manual with a schematic for anyone that cares to look.
http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Simpsons.pdf
Here's the manual with a schematic for anyone that cares to look.
http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Simpsons.pdf
