TMNT turtles in time 3rd player auto coin in?

Noobs

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as soon as it reaches the "Winners dont use drugs" screen, a coin is immediately deposited for 3rd player, i reseated the roms thinking that was the issue, but no luck :/
 
it was never in to begin with, im running this just through a 2 player jamma setup. i dont have the harnesses attached to anything yet
 
Take the board and smash it over your head a dozen or so times.

:p

If that doesn't work check the player 3 header for a short that is causing it to coin.
It might be a bent pin or have something wedged in there.
 
that would make perfect sense, i had a feeling those damn chips were the issue, after rigging up a genesis arcade stick to 3rd and 4th players, i cannot coin in anymore then the 1 coin it randomly inserts for 3rd player, but the 4rth player works fine
 
oh of course they are... now ive tried finding a source for purchasing ls253's.... but i cant find anything. does anyone know a good source to buy them from?
 
I should have a few in the bins here...

Check the pin for coin input on player 3. The pin should be at 5v when nothing is attached. If it's not then you have a bad resistor pack.

The resistor packs are used to pull the lines up to +5v (logic "high"). The switch connected to them takes the line low and the LS253 will see that as a coin input. If the line isn't tied to logic high then the LS253 thinks the switch is closed.
 
what would be the best way of going about what one is bad?

Check the schematic and in the input section see which one is hooked to thatt input. Or socket and replace and see what happens, specifically what happens when one is removed, if it boots (will it run with out maybe? Maybe some one else can comment) if you want to boot it with new ic, socket and replace one at a time if following schematic is not option or doesn't narow it down far enough for you. Etc.
 
i believe the resistor pack is bad, not the 74ls253

The resistor pack on konami boards are a little different than the usual resistor pack. From what I remember it's output then input which threw me off when I had one with the same problem.
 
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