I'm working on fixing up my White Water , which has always seemed to have one problem or another.

I don't *believe* this issue is related to battery leakage, though there was some in the past - I have since installed NVRAM.
I've had someone shop the boards previously; he repaired around 10 breaks on the board.

On to the current issue. The Left Trough was not registering closed, so the game registered a missing pinball AND would feed two balls to the shooter lane if you tried to start a game.
I traced everything in the column (7) for connectivity - no problems.
I traced everyting in the row (8) for connectivity - no problems until I made it back to the trough. Someone had swapped the Center and Left Trough - meaning the Center was now on R8 and the Left was on R7.

Seemed like any easy fix - swap them so they are on the correct rows. Which I did.

That was incorrect. The game started fine (though it thew up a sound board error on first boot but never again) and didn't feed two balls, but now NOTHING on row 8 works, and half of column 2 (from row 4-8).

Checked fuses, no problems there. Swapped it back to see if that fixed the problem, no change.

Any insights?

Checked the MPU, pin 9 wouldn’t close! Switched over to the other pins and cleared up all the problems (other than the trough switches being swapped).

Doesn’t explain the column 2 issues though - they tested fine.

Any chance flipping the connections burned out the pin on the MPU? Or was it likely residual battery damage?

I’m leaning towards doing nothing else - maybe repairing the MPU in the future.

Nokoro Yes, didn't find any problems AND swapping connectors on the MPU board 'fixed' that column - though I as able to close all those switches when testing the MPU.

bobukcat the reality is confusing as well. Let me try again.
1. Switch matrix was connected to J207 and j209.
2. Row 8 was fully out, and column two was partially out.
3. Performed the diode test between J207 and J209. All switches closed except for Row 8 (pin 9 on J209).
4. Performed the diode test between J207 and J208. Everything worked fine.
5. Plugged back into J207 and J208 - all problems solved.

So obviously the row problem was on the MPU.
And most likely something is loose between switch 24 and 25, and moving the play field led to that error (and subsequently fixed it).

So I guess my remaining question is about the likely cause of the pin 9 failing.
Was it most likely the previous battery damage?
Or could swapping switches have caused it?

Thanks for the help all -
I’m going to take the win for now and just be on the lookout for play field connection issues on column 2.
Then possibly look to replace the board in the future.