So when you test the wall-release solenoid the solenoid reset (wall up) fires?

If you drop the wall manually and then test the wall release (drop), does it raise the wall?

In switch test mode, does the switch for the wall target register properly when the wall is lowered and raised manually?

Did it ever work correctly since you had it?

Solenoid 8 test is wall target up (wall reset)
Solenoid 16 test is wall target down (wall release)

Also, you're testing the wall release twice with no mention of the other test. What happens when you test the wall target reset Sol 8 when the target is down? When the target is up?

It really sounds like the switch that reads the wall position isn't working right, or the vibration of the wall movement is triggering the switch giving it a bad reading.

Can you take a video in portrait mode so I can see the display and what the wall is doing at the same time while you hit solenoid test 8 and 16, and then the switch test while you manually raise and lower the wall?

Upload to youtube, put link to youtube video and it will insert the video in your post here.

You can also upload it to dropbox or google or something like that and post the link and I can just download it.

I think you need to make the videos public on youtube's control panel for each one. It says I can't have access because they're private.

That worked. Can you get a couple shots of the target assembly itself under the PF with the target in the up and down position and the wiring for the targets visible?

Also, drop the target then try firing all the other coils one by one and see if any of THOSE reset the target to the up position.

I can't see from the angle, but are either of the wires going to the small coil that releases the wall near or touching the metal plate?

With the playfield up where you can watch the coils, try manually dropping the wall, then doing wall up then follow with wall down in the test and see if there's any arcing or sparking to indicate a grounding or short.

Did you drop the target and then try manually firing every other coil EXCEPT 8 and 16 and see if any others cause the target up coil to fire, too?

Dup.

Ah, now we're getting somewhere.

So is it firing with literally every other coil, or only most of them? Make a note of which coils also fire the wall up coil at the same time, but test each of the other coils - don't skip any.

Also, when was the last time you changed the batteries? Was this power driver board ever damaged from battery leakage?

Right, CPU board. When you moved the batteries off the CPU board, were they leaking or the ends of the holder corroded?

So ALL the other solenoids fire the wall up, but the wall up and other solenoids don't fire any other solenoids?

Check the diode D28 on the power driver board to see if it's shorted open.

If it's not that diode and there's no battery damage, the only thing that comes to mind is IC at U5.

You might want to also try reseating the ribbon cables between the CPU board and power driver board.

Actually, it just dawned on me you have another WPC-S machine with the same power driver board in your collection, Theatre of Magic. If you still have that, you can swap in the power driver board from that (NOT the CPU board) and see if that solves the problem, narrowing down further where the problem is. Just take multiple pictures of the connectors before you remove them from ToM and Shadow so you can connect everything up when you make the swap, test, and then swap back.

That will give you an answer in about 10-15 minutes it takes to do the board swap.

The power driver board swap will narrow it down the fastest. Let me know what you find out.

Did you swap the power driver board? Did it fix the issue?

Okay, so it's likely somewhere in the wiring. That's progress.

Disconnect J127 which is all the low power solenoids. Then test solenoids 9-16. Do any of them also trigger the Wall up solenoid while J127 is unplugged?

Power off.

On the connector, use a multimeter to check for continuity between J107 pin2 and J107 pin3

Hmm. Remove the fuses F103 and F104. Try testing solenoids 9-16 again. Does the Wall target reset for any of them?

Yeah, I meant 103 and 104. You have to have both of those fuses out while testing 9-16 solenoids to see if wall up still fires. Were both fuses out at the same time when you tested 9-16?

If you swapped in the ToM power driver board and it still does it, that means the problem isn't on the Shadow power driver board, then.

By taking out the fuses from the low power and the flashers that means there isn't some kind of voltage cross.

So it HAS to be a short on the Drive wires, but it's weird that it's across ALL solenoid drive wires. I can't think of a point where they would all be vulnerable together. That's behavoir that would make me think there's a chip issue, but that would be on the power driver board, and you swapped that with ToM and it still does it, so that's eliminated.

Maybe a messed up grounding issue, too.

Had you worked on the machine at all in the days or weeks before this happened? Raised the playfield?

Bad diode on that coil ..if it has one?

Yeah, I didn't think that would help because of the way the coils are driven. It's not like the switch matrix. Since you swapped power driver boards and it didn't help, the power driver board is ruled out.

Can you take a nice picture of the CPU board from about halfway to the bottom where the switches connect? You might have to do two pictures as the battery holder will probably cast a shadow and/or block view of the full board from certain angles.

Is that a stock power driver board or a rottendog next to the CPU board? It looks like a rottendog...

Also, I wasn't sure if you answered if you were working on the machine or had raised the playfield recently before this started happening.

Also have you tried reseating the two chips at the top of the CPU board? The one with the warranty note on it and the one with electrical tape on it below.

Is the ToM board a Rottendog, too?

They are problematic.