(Topic ID: 254162)

Need help with Gameplan MPU-2 (switch issues and more)

By Chisel

4 years ago



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#1 4 years ago

Hi folks,
I have three Gameplan MPUs I'm working on, 2 have similar behavior and 1 won't even light the LED. Before I get too into it, let me say I have a fully functioning Sharp Shooter 2 that I'm testing these boards in.

1 MPU-2 rev 1 fully boots into attract mode, starts and plays a game but is not recognizing switch inputs on at least these switches:
Playfield candycane kick out hole
1000 point rollover switch on mid left side, just below 50k switch
Coin door switches
Credit/start game button
~I've replaced U18 and U23 and swapped in good chips in U17, I haven't removed and socketed U14 yet but that's next on my list.

1 MPU-2 rev 2 fully boots into attract mode, but that's it, won't start a game. Will not accept credits from coin switches but it's on freeplay anyway.
~I've replaced U18 and U23 and swapped in good chips in U17 and U14.

1 MPU-2 rev 1 as I said won't even light the LED or blink at all...

I do have a decent DMM and a logic probe but I'm a rookie with the logic probe... Any help with these would be greatly appreciated!

#2 4 years ago

bump - how about some love for GP and Chisel???

#3 4 years ago

Bueller?

Is it just too much to read? Should I break them out and ask for help one at a time?

Thanks

#6 4 years ago
Quoted from kbliznick:Also FYI in case you don't know. The boot up sequence sounds like it works like the Bally boot sequence but it doesn't.
i.e the stuff needed for the game to get to the second flash includes the stuff tested at later flashes. So if the parts for flash #5 aren't working you won't get flash number 2. I think there is maybe one flash (the 6th IIRC) that you can get to that accurately states that that part is wrong. Otherwise you get no flashes or ALL flashes and pretty much nothing in between. Worthless.
Turn off the dip switches and run the switch tests with the pf switches disconnected from the board and use a jumper wire to test the switch columns and rows. I had a bally with switch issues once and it had a couple of bad diodes on the dip switch banks.
Good Luck

Have any documentation on the boot up sequence issues you mentioned?

I'll try the dip switch banks all off, I did read some other thread where this got a board working, may help to isolate issues...

Thanks!

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