We've got a Road Kings here, and I keep getting reports that it randomly locks up in the middle of a game. The CPU board had some minor corrosion on it that I sent out to have repaired. The person who repaired it didn't really do that thorough a job - he just pulled some ICs out, cleaned under them with alcohol, and then socketed the same chips back in. It's entirely possible that some kind of corrosion is affecting the game.

I hear that the game stops working, the lamps and displays shut down, but the music keeps playing. I don't know if the coils still fire or not, as I'm not able to reproduce the issue myself. It always seems to happen when I'm not around. I know that Clay the Pinball Ninja walks into corroded board situations all the time and is able to pick out the exact component that's causing issues. But his issues are usually much more easily reproducible than mine.

Short of putting my work desk next to the pinball machine to catch the failure in action or replacing every single component that even LOOKS like it has a smidgen of corrosion on it (which I may end up having to do) what are some tests I can perform to figure out if the failure is because of one specific component?

It has just happened again, and I was able to go take a look. All the lights are out, the coils won't fire and the score displays are blank. GI is on, and the background music is still playing. The LED in the board displays what looks like a sideways F.

I took some basic voltage readings, and found between 4.86 to 4.98 volts all around. The blanking circuit looks like it was at 4.85 volts. The input voltage was 4.96. Grounding the blanking circuit reset the machine and everything played fine again.

Yeah, my wording was a bit weird. These issues were happening prior to sending the board in for repair, and have persisted through it. I'm certainly not convinced that some kind of lingering corrosion damage isn't still causing the issue. I'm just not sure where, and I'd like to at least try to pinpoint an individual component rather than shotgun 1/3 of the board.

I'm fairly certain the power supply is fine. I've replaced all the capacitors, and the display is a 5-Volt LED X-Pin. When I use the 5V test point ont he CPU board while having someone go nuts on the flippers and bumpers, there's no noticeable voltage drop from 4.96 volts.

I know it's been a while, but I'm going to give this game one last go before selling it at a deep discount or stripping it down to use as a parts machine.

The behavior it's currently exhibiting is that a not-insignificant percentage of the time, the game will lock up. It will stop responding to switch closures and any balls that go into outholes don't kick out. The special solenoids fire when triggered. The lamps that were flashing either stay on or off, depending on their state at the time of the lock. The background music continues to play, and whatever game sound was playing tends to repeat itself. The game stays like this until I turn it off and back on.

Regardless of whether or not the game just locked up, when I navigate through the audits menu, several of the reports have "ERROR" listed in their values for things like games played and extra balls gained. If I take the batteries out and put them back in, then the ERROR goes away until the next time the machine locks up.

The main MPU board has a history of corrosion on it, and I've done what I can to get it cleaned up, but there may be some left over that's interfereing with one or more components. I'm leaning towards the RAM.

Can anyone offer any advice about how to test this kind of thing out to isolate what component(s) could be causing the problem?