Hello All,
Long time Lurker with a problem hopefully the group can help me solve. I’ve had a a Fire! Machine for ten years now. It works quite well with one hiccup. About five years ago when I was playing it I noticed that heart stopping smell of burnt electronics and smoke.

The upper left slingshot coil/solenoid was obviously burnt to a crisp. I checked all the fuses and did my best inspection of all the electronics to see any potential source of the problem to include fuses, fried capacitors, diodes, resisters etc.

Not finding any other obvious problems I went ahead and replaced the solenoid/coil. After repairing it the slingshot still did not work. However, there was no new smell of anything burning or anything on fire.

I then just for fun tested the functionality of the slingshot solenoid/coil by hotwiring it to the working solenoid on the upper right. When I activated the upper right slingshot, both solenoid/coils fired, which tells me that I had a correctly working solenoid on the left as well.

I tested the resistor on the left slingshot and it seemed to register as specified, I swapped out the one leaf switches which include the resistor and capacitor with a used one I had and the unit still did not fire. However, the solenoid at this point did remain “on.” I turned off the machine after 10 seconds so likely I did not fry anything.

I reversed the black orange wires on the switch (maybe I wired it in wrong) and the sling shot did not fire but it also did not remain on.

So after this long diatribe, I was wondering where I should I look next? Is there something on the MPU I need to investigate? (Somewhere I read U7 may be responsible for this slingshot.)

Any help would be appreciated

Fortunately my PinBot is still in good shape

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Thanks for the reply.

No it does not lock on when I turn on the machine. Yes I do have a multimeter.

Ok, I’ll dig through the schematics to try and find which transistor it is.

The smell test is negative for now, can’t find anything

Well I found the likely culprit . . . A fried TIP 122 transistor at Q73. It seems like a straightforward repair . . . But I’m worried I’ll screw up an otherwise good MPU.

Fortunately, (amazingly) there is a pinball repair shop in my hometown Glendale CA, so for $125 they will replace the $2.00 transistor and give the board a looksey for other problems.

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Yes you are correct. The tech mentioned likely having to change the square component directly above Q73 (the pre something or another . . .)

I’ll admit, I’m Dying to try the repair myself. Especially because I’ve got all the correct equipment at home to do it. But I know it’s probably wise to be patient and let a pro do it. It would be nice if they let me watch the repair.

I’ve already replaced the diode and coil. It was after that I discovered fried Q73.

Don’t think I haven’t already started practicing. . .

I appreciate the kind intent . . . but it is what it is. In the long run $125-150 is still cheaper than a new MPU (unless I blow another transistor.)

Hey if I wanted a cheaper hobby I could always take up Crochet. I practiced desoldering and did OK, but as Good Old Clint Eastwood once said “a man has got to know his limitations.”

Regards

I pulled the board this morning. There is a burn area around Q73, but the pre transistor “looks” ok. The board connections from Q73 to the rest of the components measure intact via a volt meter.

I will drop by the Pinball Repair shop this morning and have them take a look, hopefully they can do it on the spot.

Thanks everyone for your thoughts and suggestions.

UPDATE: A HUGE shout out to Gene at Vintage Arcade Superstore in Glendale. He replaced Q73 (with a TIP 100) and also replaced the pretransistor for $75; but the best part was he did it while I waited. His showroom has literally 100’s of machines from the 50’s to now.

I played as many as I could, I only wish the repair took longer, there were more games to play.

Thanks to EVERYONE who helped me resolve this issue. . . but beware . . . I’ll be back, I’ve got a PinBot that still needs restoration.

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He offered to install the NVRAM ($100 ish) but I’ve already done the off board battery upgrade. No Battery Corrosion potential on my MPU.

Additional Update: One thing I’ve noticed which really shouldn’t be a remarkable revelation is that the left upper sling fires with more force than the upper right. The new AE 24 900 coil on the left is making the original 31 year old one on the right look bad.

I’m probably going to have to start replacing all the coils.

Again thanks Pinside for everything

Thanks for the great advice. An even easier fix, and cheaper.