I'm hoping folks can chip in here on helping diagnosing a switch matrix issue and what I suspect is a blown diode (note nothing was changed and this was working just two days ago). Here is the run down on symptoms:

* When a ball is in the shooter lane the right sling solenoid fires.
* During a single switch test if the shooter lane switch is pressed the right sling solenoid fires.
* If the ball is resting on the shooter lane switch and certain other switches are pressed the sling solenoid will fire (specifically the coin door menu switches).

I'm suspecting that this is a diode issue because the right sling switch is one above the shooter lane switch. shooter lane is #53 and the sling is #52. I believe that would mean that the diode for the shooter lane switch is the likely culpret, but wanted to check with the forum if I should be doing some other testing or if I'm off base. Let me know. Thanks!!!

All - Just a heads up and asking for any more advice folks may have. I have identified this to be an issue that is not in the cabinet. It is happening on the board.

If folks have any starting tips on the approach for the board I would appreciate it. Since the ICs - U16, U18, U19 and U20 are socketed on the board I'm going to replace them to start. Any other things I should do to get started?

good advice I certainly will go for it one at a time.

All an update and any help would be greatly appreciated. Here is my status. The issue is on the CPU board. I disconnected the switches and did a jumper test directly on the board. The issue is also not the U 18, U 19, or the U 16 chips. I replaced them one by one testing the issue in between each replacement and the problem persisted.

Here is the latest new information on what the symptoms are. The issue is specific to row 2 in the switch matrix. For any switch in that row it will register the switch being triggered but it will also trigger the switch immediately to its right on the matrix. For example when I trigger River E at 32, it will also trigger Light Lock Right at 42 (and so on). It will do this for all of the switches in Row 2. Oddly when I test any of the switches in row 3 this doesn't happen, however the Ball shooter switch sits at 53 and that was activating the right sling too, but the double switch behavior doesn't seem to be happening when I using the jumper method test.

Thoughts?

I'll take some pictures this evening. There was definitely work done on it before I bought it in 2007. So this could very well be the issue, but it has worked fine for over 15 years so seems odd that it is cropping up now. That said you never know.