(Topic ID: 254162)

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

By Chisel

2 years ago



Topic Stats

  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by Ilikewires
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#1 2 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 2 years ago

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

#3 2 years ago

Bueller?

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

Thanks

#4 2 years ago

Gameplan MPU's suck hardcore when it comes to repairing them. Tripley so if they have battery corrosion.

What game eproms are in the MPU's? Are they all Sharpshooter 2 roms or are you swapping the roms from a 4th known working board that came with the fully working game?

Gameplan heavily recycled the game software/rules from title to title but they aren't identical AFAIK.

Are the boards strapped correctly for the ROM sets you are using? Never found a good source that correctly identifies what to do and these boards are notoriously fickle that I was always afraid of messing with ROM jumpers on these turds.

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
I fixed a shit ton of these about 10 years ago. Got around 10 out of 20 working. Kept 2 spares on a shelf. They didn't last a year sitting. Pulled them to use and both had died. Awful systems. The batteries usually manage to wipe out around 12-17 chips and their traces.

#5 2 years ago

I have a Pinball Lizard. I ordered a replacement MPU from Jim Francesangeli - I think you can probably find him here on pinside. His website now says closed but he may still making replacement boards. I bought this one a couple of years ago.

#6 2 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!

#7 2 years ago
Quoted from Chisel:

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

I don't recall if Clay mentions this in his guide for Game Plan but have experienced it first hand a couple of times on the boards I was repairing. The boot up sequence they wrote needs some components right from the first flash that are then "tested" by later flashes. I only ever got less than full boot but more than 1 flash where the bad component matched the flash ONCE (think it was the 6651 RAM test). Several other times I had boards that got a single or no flash and it was the 3rd, or 5th or later component halting the boot prematurely (one time think it was the 6840 or 6540 or whatever that part next to the Z-80 is)

Bad Engineering. They wrote a test sequence that only in effect confirms a 100% working board, anything less than 100% and you aren't really testing anything.

You can confirm this on a good board. Simply see what makes the last flash and remove it and see if you get full minus one flashes. Put that part back in then take the second to last component out and see if you get full minus two flashes. etc. all the way down to the first flash. Please share your results. Then to really finish documenting this see what happens on any component that actually matches the flash by removing all the components from after that flash and see if it still reflects that part correctly. You can actually do this with a Bally board with the exception that one of the PIA's that is tested again later is needed to make the LED flash.

1 year later
#8 1 year ago

Ahoy folks, I have posted in new products a preview of my replacement Game Plan MPU design.. please have a look at it.
Chris~

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