This one is getting frustrating, but maybe I'm not looking at something right.

This one started out with some play field lights coming on at power up and that was it. At this point, only the right kicker is stuck on, and one row of lamps (row 3 in this games case) is locked on. I haven't looked at the lamp issue yet, because I'm more concerned about the locked coil.

All connectors on the boards have been re-flown with new solder and the pins were cleaned off and shined up with a wire brush on the Dremel tool for a nice sharp "new" look free from oxidation. And we came up in diagnostic mode, with all displays on and functional.

No switches are stuck on in diagnostic mode, all displays work properly, and we can start up a game, but what's that smell?

There were 4 coils not working. 2 coils were non functional and 2 were locked on, so I replaced 4 sets of driver/pre-driver transistors on the driver board, turned the game back on, and it's down to 2 coils locked on. I removed the resistor and capacitor from the one locked on pop bumper (needed just to give it a little extra "pop" but not to function correctly) and the pop bumper works now. Replaced the shorted resistor and added a new cap and its good to go. One coil left that is locked on (right kicker). Try the resistor/cap route again, no change. I replaced the 2 7402's at IC8 and IC9, no change. I replaced the 2 7408's at IC6 and IC7, no change. I replaced the PIA at IC5, no change. I replaced the PIA at IC11, no change. I went back and replaced the driver/pre-driver again just in case something had happened in the split second that the machine was on to see if the coil was locked on still, no change.

What else is there? I have thoroughly examined both stand up switches and all connection points of wires and connectors for the circuit and I haven't found any broken/loose/cracked wires anywhere and the switches are clearly not touching to keep it locked on either.

The special coils are also controlled by the mpu board correct? So, could it be something on the mpu? I don't know what else to look for on the driver board.......

This seems to be a real fun game to play, even without background sound. I unplugged the wire for the right kicker so I could actually play the game with out the right kicker locked on. Once I got the drop targets cleaned and functional again it's playing fast and smooth. There were 2 small spots of wear on each drop target board so I added a little pad of solder onto each one and buffed it down smooth so they would make proper connection and drop/reset smoothly. Everything scores correctly and the game steps through all functions properly at this point.

But that damn right kicker is killing me!

Thanks!
Kevin

Viper:
Thanks for the suggestion Viper, but I've already removed the resistor/capacitor on the sling with no change.

Wolf:
For shorts to the back box, should I just look into the grounds? Obviously it's getting power since it's energized... it just needs to return back to the mpu to complete the circuit, and not be held high right? The way I understand it, the special coils have 2 triggers, one from the mpu in test mode and one from the driver board during game play, so if the circuit isn't completed at power up, it's just going to hold the signal high and be energized. Is that right?

Kevin

I was going to look in to the possibility of wire shorts, but my meter isn't working right. When I opened it up there is a burnt resistor..... not sure how that one happened!

So, after I replace that I'll look in to shorted wires and solder splashes and report back.

I did just re-flow all the connectors so it's certainly a possibility.

All of the wiring checks out good in the circuit from the driver board to the play field and back again from both the coil and the 2 stand up switches associated with the right kicker. I went ahead and looked in to the row/column of switches diodes again just to make sure, and those all checked out good as well. After a couple hours of all that poking around, I took my Flash driver board out and put it in the Tri-Zone. I normally hate doing that unless I just have an extra working one around, since I don't want to have a game down that I've already got up and running.

The Tri-Zone is working perfect now with the other driver board. There is just something I'm missing on that board that has to do with that special coil. Maybe one of the chips I put in has the same issue as the one that was there.... ugh..

I looked for solder blobs and trace scratches/cuts and didn't see anything on the driver board.

Next thing to do would be to get a logic probe and work through the circuit to find out where the issue is right?

Any advice on a good logic probe, or where to start working through on that one? It's special coil #5, 21 overall, and pin 8 at the driver board connector, the straight to the driver, then pre driver, then 7402, then 7408, then PIA, right?

Could the resistors by the coil driver/predriver have anything to do with the issue?

At least I know it's strictly a driver board issue now....

I know it's been a minute, but I'll get on to that.

Thanks for all the suggestions and I'll let you know what I come up with on the board.

I've got 4 driver boards that all need work right now, to get figured out.