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(Topic ID: 261421)

F-14 pop bumper help


9 months ago

Topic Stats

  • 31 posts
  • 3 Pinsiders participating
  • Latest reply 9 months ago by GRUMPY
  • Topic is favorited by 1 Pinsider


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#1 9 months ago

Hoping to find some help fixing my F-14 tomcat. The pop bumper worked on and off for a while, now doesn’t work at all. Switch test doesn’t acknowledge the pop switch. Coil test does not fire pop. I read on another forum i could test the coil by grounding a wire on the game frame and connecting to the ground on coil. This worked, the pop fired. Also saw i could connect the switch terminals at the cpu directly. Did this during switch test and it acknowledged the switch. So I’m stuck here. If it’s something in the wiring from the switch to the cpu, then why wouldn’t the coil fire in coil test?

#2 9 months ago

have you verified that a wire didnt come loose or your spoon break?

#3 9 months ago

Took the switch off its mount and didn’t notice loose wires. Spoon is intact and appears the actuator is sitting in there properly.

#4 9 months ago
Quoted from THEFOZ:

So I’m stuck here.

If the pop does not fire during test, but fires when you ground the metal tab of the transistor then you have a CPU board problem.

Do you have a logic probe or a voltmeter?

#5 9 months ago

Just to be clear, I grounded the single (colored) wire on the coil, not the transistor on the cpu board.
I do have a voltmeter.

#6 9 months ago
Quoted from THEFOZ:

I grounded the single (colored) wire on the coil, not the transistor on the cpu board.

Ok, testing like that does not confirm that the wiring back to the CPU is good. Grounding the transistor ensures good wiring and board connector.

#7 9 months ago

I will give that a try and update. Do i just ground the metal tab that sticks out from the board?

#8 9 months ago

Grounding the Q69 transistor does nothing. Grounding other transistors activates their associated coils.

#9 9 months ago
Quoted from THEFOZ:

Grounding the Q69 transistor does nothing. Grounding other transistors activates their associated coils.

So this means you have a break between the transistor and the coil. If you find J-19 connector on the cpu board and remove it. Then take your ground wire and touch it to the blue/yellow wire in the connector does the pop fire?

#10 9 months ago

It does not fire, the other ones on the connector do though.

#11 9 months ago

There are some large and small molex connectors that are for disconnecting the play field. Find the one that has the blue/yellow wire. See if the wire has pulled loose or that one of the pins has popped out of the connector. These connectors are hanging below the back box.

#12 9 months ago

The connectors look good from what i can tell. One thing I notice is that the wire to the coil under the playfield is green with a continuous yellow stripe (not blue with circular yellow). Maybe it changes at the connector? The switch and bumper both worked when I got the machine, then intermittently- and lately not at all.
By the way, thanks for all the help so far. May have to hang it up for the night but appreciate your responses.

#13 9 months ago

I think you should post a pic of the pop. Green/yellow wire should go to points switch. The coil should have 2 18 gauge red/white wires and a 22 gauge blue/yellow wire.

#14 9 months ago

I’ll post a pic after work. The wire to the coil is definitely different than wire to cpu.

#15 9 months ago

Coil and board connection pics

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#16 9 months ago

Different wire but to me it still looks like a blue/yellow wire.

Quoted from THEFOZ:

Maybe it changes at the connector?

Yes most likely does. Can you find the connector with this wire on one side and the darker blue wire on the other side. Make sure that the pins in the connector haven't come loose and are pushed out the connector housing. If they look good then separate the connector and use you meter to test each side for continuity. Let me know what you find.

#17 9 months ago

I think at the connector the blue/yellow changes to green/yellow stripe. I’ll try to get a pic

#18 9 months ago

I’ll try to check but need some help (hard to get to).

#19 9 months ago

That proved difficult with my wife, but i did check continuity from coil lug to blue/yellow on cpu board and it was good?

#20 9 months ago

Coil test still doesn’t work.

#21 9 months ago
Quoted from THEFOZ:

Coil test still doesn’t work.

How did you do the test?

#22 9 months ago

Through the game diagnostics- coil #20 shows up w no action

#23 9 months ago

Try it again using a jumper wire that is connected to ground. Touch it to the metal part of the connector.

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#24 9 months ago

Nothing. Every other connector i ground fires a coil. Same w transistors (except q69)

#25 9 months ago

This is the problem with intermittent connections, you check for continuity and it's good. Then you try to apply current and the connection opens up. So somewhere between J-19 and the coil there is a break. You can separate the molex connector under the back box and then reconnect it to see if that helps. You can connect the ground jumper to Q-69 with a alligator clip and then move the blue/yellow wire around looking for the break. You can also run a new wire if nothing else works.

#26 9 months ago

Thank you - maybe I’ll try to just run a new wire directly. I appreciate the help, I’m new to troubleshooting pinball and don’t have a lot of practical electronics experience. I’ll let you know if it works- might be a couple days. One more question- is it possible the transistor is bad?

#27 9 months ago
Quoted from THEFOZ:

One more question- is it possible the transistor is bad?

It is possible, but then you would have 2 issues at the same time. If you want to test it with the ohmmeter you can. Place the game in coil test and stop on the pop coil. Place red lead on the J-19 connector blue/yellow wire and black lead on the ground braid. As the CPU pulses the coil the meter will flicker just like if you were to touch the meter leads together then separate.

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#28 9 months ago

I put red lead on transistor and black on ground - nothing. When other coils pulsed, i put red lead on associated transistor and black ground. Meter would pulse between -1 and 1. Didn’t do this with q69, but did with others while they pulsed. Does this mean transistor is bad? If so, how do i fix?

#29 9 months ago
Quoted from THEFOZ:

Does this mean transistor is bad? If so, how do i fix?

It could be a number of things, Q-69, Q-68, U-45, R-94, R-95, U-49, U-38 and cracked solder joints. You can test with your voltmeter.

#30 9 months ago

I feel like I’m entering the 7th level of hell. I will continue the battle, again thanks for the support.

#31 9 months ago

Pretty standard issue for this older pin. The divertors usually melt down too.

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