Short version: A kickout hole coil always seems to be slightly energized. A bit more during gameplay than attract mode, but still, always seems engaged just a bit. It fires properly during gameplay to kick the ball out with full power, but then seems to go into a low-power mode and hold the plunger barely magnetized.

Longer Veriosn: Working on a System 80A game, and I'm having an odd issue I've never seen before. There's a kickout hole that, during gameplay, will sit inert until triggered as it should. Once it fires, it will kickout the ball as expected, but then stay locked on... sort of. It doesn't appear to be fully locked on with complete power, because I can press it down about halfway and it will release to being inert again.

I powered off the game, checked resistances, coil seemed okay. I powered the game back up and checked it during attract mode. There is actually a very slight pull on the coil even, in Attract mode. It's so minor that you have to push the plunger all the way down inside before it has JUST enough magnetism to hold the plunger pulled in. Barely pressing the armature back down releases it. I've run into plenty of locked-on coils in my time, and plenty of dead ones, but I've never seen a non-flipper coil that's a weirdly semi-low powered coil at all times, even in attract mode.

Thoughts? Didn't know if a bad/failing transistor could cause odd behavior like this, since I haven't seen it before.

Okay, so a failing/bad transistor can cause semi-energized behavior, but still pull full strength when triggered normally? Interesting. First time I've seen/heard that. I'll go test the transistors and see what readings I get.

JethroP replaced both the driver and pre-driver, no luck. Very bizarre.

I'll take a look, thanks for the suggestion. Sort of seems like once the plunger gets fully into the coil, it gets stuck in there magnetized. If the bracket and coil stop are magnetized, I guess that might explain it? Why would it be stronger when in gameplay vs. attract mode, if the power is always to the coil? Hmm.

frunch Tuukka

Good idea on the grounds, they aren't done. Somewhat silly question: the ground of the regulator frame, where can I check that against to make sure it's good? It's not cabinet ground, correct? I just want to make sure it's good before running all the wires to it. I noticed two screws to the frame were the wrong size, and another was missing.

Regarding the idea of separating the coil stop a bit, I tried that and it seems to eliminate the issue. I used a small rubber piece though, so it may just be that I'm preventing the plunger from going all the way into the coil. I'll test some more.

Really good explanation Tuukka , thank you. I was following the grounding directions in your original link, but having the additional info helps me understand the theory more.

Is there a recommended wire gauge? I have a lot of 18 gauge green handy.

Regarding magnetization, great point about powering the game off. It instantly releases the plunger when I do that, which would make magnetized less likely to be the issue.

I'll go work on the grounds now and report back.

Tuukka You nailed it. Adding the ground mods to the driver board and filter capacitor to regulator frame did the trick. The coil is now functioning 100% properly, no extra pull when it shouldn't be. I checked it in attract mode and during gameplay, the plunger moves freely without being grabbed by the solenoid, and when the solenoid is triggered during gameplay, the kick out works fine, and armature falls back down immediately as it should.

Serves me right for not doing the standard ground mods right away! Definitely learned something new in terms of ground issue behaviors. I had never heard of this problem before with regards to those, so it's great knowledge to have. Thank you! And Thank you to everyone else who chimed in with ideas.