If you have credits on the machine, does it remove them when this happens? You can manually add credits to the replay register, then place the balls by hand.

If you don't have a winner on your first three balls, does it tilt immediately when the fifth ball leaves the shooter lane (if you make three in a row in the first four balls)?

I suspect that you may have a short in your scoring circuit - this is the area beside the search disc. But first, let me know the behaviors above and that'll help verify. If your credits do not roll off, then the anti-cheat is not disengaging, and you have something else going on (maybe a switch that's too close on the tilt trip relay, which should be near the selector lock - this relay trips when the fourth ball leaves).

Does it happen on any game, even if there is no winner?

Also: this is silly, but have you check the plumb bob tilt and slam tilts to ensure they are not super close? That's probably the easiest thing to check. Should be one on the back of the door, one on the bottom of the cab, and the plumb bob will either be on the left or right side, behind the lifter.

Basically, something's touching that shouldn't.

You have a short in your 50v somewhere in your scoring circuit. Or a coil that's gone bad.

Do some tests and verify if it happens on certain colors.

That'll narrow down the possibilities.

Well, at least it's consistent. It's only happening when scoring, so it is unlikely connected to the search relays.

Note that this problem will be a bit tricky to track down, so patience will be required. (Not that you haven't been patient thus far! Just note that this problem is not a quick fix.)

I would suggest trying the following first:

Examine the back of the selector lock relay - make sure there are no switch tabs touching, broken wires, etc. This is on the trip bank on the back door and is normally labeled. There are two stacks of switches and each switch must operate properly. If you have, for example, a single-pole double throw switch in there that connects the scoring circuit, and also disconnects it, that could cause the short. Your manual will have an explanation of every switch on the selector lock relay and what it does. Look at this and see if anything matches up kinda sorta with the behavior you're seeing and start there.

Then:

Examine the search index relay. This has a sand wound resistor that can sometimes fail open or come unsoldered. Normally, this doesn't send it to tilt, so check that area carefully. Be very careful not to poke those switches, they are quite delicate.

We basically have to isolate each 50V coil in the scoring system - which is all of the scoring coils Replay counter step ups, search index, search relays, and selector lock.

The selector lock is something I highly suspect as it happens right when the ball leaves the gate with a winner.

That switch simply turns on a lamp inside the coin door so you can easily check the meter numbers.

Buuuuut, if the coin door is open and doesn't cause a tilt, check for pulled or pinched wires, or at the coin door jones plug for maybe some wires touching.

The extra ball feature also is governed by the fourth ball being shot, so perhaps the issue lies there? Check the switches carefully behind the yellow button and follow the wires back over to the plug.

Hmm, sounds non-factory to me. Can you snap a pic?

Ah, OK. That switch is a slam tilt. Can't remember if that should be no or NC. I'll take a look later today.

What's happening is that your 50v is sagging when something trips or tries to activate. This releases the anti-cheat, which acts as a kind of soft tilt or failsafe if 50v sags.

The anti-cheat is on the right side near the top behind the backglass.

But it is working properly. Your problem is one of the other solenoids.

Perhaps desolder one lead of the selector lock relay, then manually trip it with a wooden dowel or something and see if it scores...

You want the before 4th - it happens when the ball leaves the gate with a three in a line on the table.

No problem, no guarantee we've found it there.

Butch, yep, in my experience that happens with a short in the 50V. Any thoughts on this?