That transistor has exploded from high voltage getting on to the low voltage circuit, most likely from someone adjusting a pop bumper switch with the game on.

I would look at u-49 first.

Take a pic of the wires that you soldered and where you had connected them.

Could the loose wire have possibility touched the coil wire above before you found it.

This didn't do anything but stop some switches from working.

No. You need to let us know exactly which coils don't work, this helps pinpoint the problem.

If you disconnect J-8 and J-10 from the CPU board, then power on the machine. Open the coin door and lock down the middle button. Press the advance button once, then unlock the middle button. Press the advance button 5 times and lock down the middle button right away. You are in coil test now and it is repeating solenoid #1. Now each time you press the advance button one time you will advance to the next solenoid. Go thru and test each solenoid and compare to the manual page #2. There should be 26 solenoids, note down the number of the solenoids that don't work. Let us know what you find.

A slight clicking sound is fine.

Check F-2 and F-4 fuse on the power supply. One of these maybe burnt.

This is the power supply, F-1 is on top.

dd5db95c76b2aca238a85f62740ff663c28fb735 (resized).jpg

If you look at the top of the power supply there is a label showing all the connections and the fuses.

You need to test them. Looks can be deceiving.

Do you have a voltmeter?

Left one is burnt, right is questionable. Do you have another fuse? If so turn on the game first and then touch the fuse to the fuse holder. Do you hear any coil locking on?

What do you have?

You can you F-2 for this. Just briefly touch it to the holder and release.

Look at the 4 pops and the 2 slingshots when you touch the fuse to see which one is bad.

You got to release it quicker. Try it again with the 4 amp fuse.

The coil is stuck and not making noise anymore because it isn't moving. Turn it off and move the coils by hand looking for a stuck of dragging plunger.

Sounds like this needs some work.

Cut and insulate the thin wire off of the coil.

Its blue/brown.

Tomorrow find some more 2.5 amp fuses and replace F-2 and F-4 on the power supply. Then rerun the solenoid test, all coils should work except for the left kicker.

If the coil test goes correctly then you can pull the board and send it off for repair.

Needs a new sleeve and clean/polish the plunger, then it will work like new.

It just happens sometimes, 30+ years old electronics. Shit happens.

Not a bad price.

Yep.

You should buy yourself a early Christmas present, a DMM. You need to check the ohms on the coil that locked on to insure that it's not shorted out. Then you need to replace the diode on the coil with a new one, the silver band facing the red power wire.

Correct, this coil has been locked on a number of times now. That does damage to the diode, so you need to replace it.

I would replace this diode to. It should look like this. (pic below).

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Any time you wire a switch it should be like this. The NC tab of the switch is only used as a connection point for the diode and the wire, this is the same as the terminal on yours that I marked with the red arrow.

switch diode (resized).png

Maybe this may help.

a (resized).jpg

Playball!

You can't switch the wires on a coil that has a diode on it. This pic of yours is the correct way the wires need to be connected. The red wire is the power wire and it must be installed on the same side that the diode band is. Reversing the wires causes a dead short thru the diode when the coil fires, this will damage the diode and the drive transistor.

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Here is a couple of pics to try to clarify what I mean. It doesn't matter which way a coil is mounted, it doesn't matter which way a diode is installed, but it DOES matter which way you mount the wires when there is a diode on a coil. Always put the power wire(s) on the silver banded side of the diode.

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coil 1 (resized).jpg

coil 2 (resized).jpg

coil 2 (resized).jpg

Turn off the power.
Remove J-18 and J-19 from the cpu.
Take your voltmeter set to ohms and test Q-75, black lead on ground and red lead to the metal tab of Q-75. what do you read?

This really blue with a brown stripe. You can find this on page 2 of the manual. It is also smaller in diameter then the red wire. Just so you know the larger wire(s) on a coil is the power wire.

Q-75 is bad for sure.

TIP102, 1n4401 and 1n4007.

I would check ZR-4 for a short if you have these on that the board. Maybe U-45 is going bad causing the locked coil.

My mistake, should 2n4401

TIP102G is fine.

2n4401ap
That should be fine.
To check ZR-4 for a short you need to remove 1J-19 and 1J-18 from the cpu board then power game on and test 1J-18 pin 5 with your voltmeter.

Early boards didn't come with zener diodes in the design. They were added in the 11A design. So on some boards the factory added them to the back of the board. So if the test shows 5 volts then there is no zener diode or the one installed on the back is good. If it shows zero volts then the zener diode is shorted and needs replacing. Yes, black lead on ground.

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Yep,yep and yep.

You can check the zener diode before or after your choice.

Go find an old circuit board and remove some parts for practice.