So I have a sort of strange issue with my Firepower pin.

I picked it up a few years back non-working. I rebuilt the driver board using Vid’s guide and replaced the MPU with a rebuilt one.

Everything was working until it wasn’t. The upper right jet bumper coil would lock on when starting a game. It would also lock in test mode. Same behavior when I disconnected J13 from the board.

I traced it back to the transistors and chips associated with the coil, replacing the suspect parts but it still never worked. I also installed a solenoid fuse saver board board (https://pinside.com/pinball/forum/topic/special-solenoid-saver-board-for-wms-3-7) to prevent any further damage to the boards.

I decided to replace the original MPU and driver boards with Kohout MPU and driver boards. With the Kohout boards in place the upper jet bumper works, however the right sling now locks on. Same behavior as the upper right jet bumper when using the original boards. It also locks in test mode; both with or without J13 connected. I would imagine if there was a playfield switch issue, the same error would occur with either set of boards.

Should I be looking for an issue on the board or a short with the playfield wiring? I know it’s always possible but I find it unlikely that there is an issue with the Kohout boards.

Thanks,
Robert

Thanks.

I ordered some parts (including diodes) and will replace and test when they come in.

I'll report back.

-Robert

Update.

I replaced the top right bumper coil, the winding wire actually broke when I was replacing the diodes. I replaced all of the diodes on all of the coils just for good measure.

I still have the same issue. With the Kohout combo boards, the right slingshot coil locks when I start a game. With the original Williams boards, the top right bumper coil locks when I start a game.

Since these coils work with the other boards I suspected there is a board issue with each one. I disconnected J13 and still have the lock issues with each board and can confirm it is a board issue.

The Kohout board: Since this is still under warranty I emailed Jeff for some guidance. I think there is something up with the switching as with the Kohout board in place, the switches for the right slingshot are shorted, actually further back the wires going to the switch are shorted-the switches themselves are good. That could explain why the right coil is locked on when a game is started. Maybe a short on the board?

The original Williams boards: I checked Q6 and measured .5volts on the outer legs. I swapped out both ICs 6 and 8 and the PIA chip as these are all socketed. I still have the same issue. Maybe Q6 tests good but is actually bad?

What should I be looking at next?

Firepower is a great game, but not so much when the top right bumper or right slingshot are not working lol.

-Robert

I tested IC 6 and IC 8

IC 6 7408

1 = .495 14 = .157
2 = .499 13 = short
3 = .504 12 = .499
4 = .492 11 = .504
5 = .499 10 = .489
6 = .504 9 = .499
7 = Short 8 = .504

IC8 7402

8 = .508 7 = Short
9 = .504 6 = .508
10 = .412 5 = .504
11 = .508 4 = .416
12 = .504 3 = .508
13 = .416 2 = .508
14 = .157 1 = .586

Does this seem right? Not sure if Pin 13 on IC6 should be grounded.

Just an update.

Jeff got back to me and said there have been situations where the back of the driver board was contacting the mounting brackets. That looks like that may have been the case as when I did not tighten the boards to the mounting brackets the problem went away. So I used fish paper on the back of the PCBs and was able to tightly mound the PCBs to the brackets and everything is working 100 percent.

On the original boards I replaced Q5/Q6, IC6, IC8 and IC5 but still had the top right coil locking, I think the next thing to look at is IC11?

-Robert