Just checked mine by pulling the cable from the sound card. The voltages of the three grey wires coming from the transformer to the sound card are:

1) between either outside wire to the center wire: 8.9vac (both should read the same)
2) across outside wires: 18.5vac

Something else is going on there. the resistors you replaced are for the switch matrix, so you should verify the switches all still work correctly as well. Are you certain you have all of the driver board connectors in the right locations? ie. They should each be keyed differently so you should NOT be able to mix them up. Verify the keying is in-tact and unique for each plug.

Also, if for some reason you had the connections to the playfield (from the head) disconnected and reconnected, theres a chance you could have accidentally cross connected two of the harnesses. it will cause this behavior as well. On my Gorgar there are two identically shaped connectors, but with different color plastics (black should go to black, white to white). Verify all of your connections before going any further with the power on.

Thanks for posting the video. That helps a lot!

While it has been a very long time since I've used the on-board lamp matrix test, I do know that you can use the Pincoder lamps test to help isolate which bulbs should be flashing/on/off in a controlled way. So you can set one lamp at a time to be flashing etc and the rest should be off. As Robotworkshop pointed out, you may have either bad diode(s) in the lamp matrix, or perhaps the lamps PIA, pre-driver, and/or driver transistors are misbehaving.

You do need to isolate the bulbs one at a time in order to tell where the culprit(s) may be. Try the on-board lamps test and if it doesn't help you track things down, try the Pincoder stuff. You can download the software and then read the 09-lamps.txt file for information on how to troubleshoot. It may shed some light on using the built-in test as well.

However, before you will be able to effectively do that, you need to ensure the switch matrix is functioning properly so you can control the tests.

IC10 Pin 5 could be the culprit. It's one of the shady AMI brand chips.. the bad news is none of the PIAs on that board are socketed and I'm going to assume you don't have the tools to remove the chips without damaging them.

If you did have a proper heat gun and an IC puller you could remove IC10 and at least one other PIA, put sockets in their place, and then *swap them* back in to see if the problem moves to the other set of circuits.

Also, removing 40 pic chips in this fashion is still a delicate process. If you decide to go this way you should practice on a junk board to get the hang of it.

I agree however, that it's pretty odd that everything worked before and that the chip dying at this particular point in time is highly co-incidental. Still, it needs to be checked.

Something in the driver board is being triggered to send that out. Wiring wise it has nothing to do with the actual flipper switches, as they are not sensed by the driver or mpu board, so it has something to do with a possible power fluctuation.. flippers do draw lots of current. Try it with the solenoid/flipper fuse removed and see if it still happens.

As for the hair dryer thing, perhaps you have a cracked trace somewhere in that area, or a pad not fully connecting.. it will be very hard to see, given that heat allows it to expand enough to connect. likely more than one trace too. Continuity test may not even pick it up..

Your board does look very clean, but I do see some sort of cut/scratch in the area between the decoder chip and the diodes.. Is that anything to consider?

Also, you might want to add a little more solder to the top side of that decoder chip. Can't hurt.

Thanks for the update, glad you have a working game!!

power off, Pull batteries, open coin door, power on, wait 2 seconds, power off, wait 2 seconds, power on, close coin door, insert fresh batteries.

If problem persists, replace 5101 chip.

Yes it is.

If you have a chip programmer and 2716/2816 chip you can run the "03-cmos" test from this software download:

https://pincoder.ca

It will test every address within the chip and let you know if its actually faulty or not.

If you don't have a chip and programmer you can buy the Pincoder Adapter. Just plug it in and turn on the game to start running diagnostics:

https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/

Of course, there are additional tests included so you can test your whole game.

If you do need to replace the 5101 and can't find a replacement:

https://nvram.weebly.com/nvram.html (Currently out of stock)

Sounds like you may have tested with the power switch on? When you are testing battery power, the power must be off, and the batteries of course, installed.

To get into audit mode, you should pull the batteries, coin door open, power on. Once you are in audit mode, install the batteries, then power off, wait, then on again. Do not power on and off quickly, or off and on quickly. This is not good for the electronics.

Excellent. Nice work!