Shop notes from Rapid Fire:

 

General Info:

Parts not listed in the service manual:

Tech notes:

If an opto switch doesn't always register, the 2n3904 transistor is probably broken or has a cold / released solder joint. I had 3 bad switches, 1 with shorted transistor, 2 were just plain broken loose. The broken were intermittant, so I decided to preventatively resolder them all.

My machine had 51 balls when I got it. An extra 50 from McMaster-Carr was $15, p/n 9528K26

Check your rubber rings! Each of the "tank" switches use 2, and mine had been beaten to death.

Advice:

Keep the playfield & ball loading areas clean and unwaxed. Wax seems to get distributed around the playfield, creating unique but distracting trails wherever the balls roll & bounce. Besides, I'm not sure what role wax would play in protecting the playfield plexiglass cover.

Other:

This thing is heavy. REALLY HEAVY. If your primary method of moving pinballs is the "armstrong" method, be sure to pull off the head & empty as much out of this thing as you can.


History & Repairs:

Previous owner never had machine working. Bought it, only GI came on, and left it in garage. Spent some time as a home-use machine, with a (broken) button in the coin door to trigger the RH credits. At some point in it's life, it appears that a can of Coke was spilled inside. It made a few parts kind of nasty, and may have contributed to failure of a few diodes (see repair log). A PO had also been rigging the firing pin return spring in a pretty awful manner, essentially hooking the spring to the firing pin, feeding it out of the back of the gun assembly, and pulling it around the underside of the gun, finally wrapping it around an unused metal post. I found about 4 broken springs inside of the cabinet... for some reason, all these springs were broken around the point of contact between the spring & the metal rear bracket that it was fed through...

Circuit boards were good, save for an acid-eaten MPU. Damage extended out to a few caps, resistors, and coil beyond a standard Bally acid repair kit. Half the fuses were wrong - a 20A in a 5A spot... a 5A in a 20A spot (not sure how that one held on without popping).

Artifacts:

Repair log:

Rebuilt battery damaged MPU using kit from GPE & extra parts from Digikey, added battery holder.

Replaced incinerated diodes CR1 CR2 on "ball delivery sensor & motor control" board (possibly related to soda spill)

Upgraded MPU & Solenoid board using pinrepair.com guides.

Changed out around 25 burned / weak lights & replaced about 6 bad bulb holders.

Lowered HV supply to 170V

Removed PO-installed incorrect return spring (too high of a spring rate), replaced with lighter tension spring. Formed a cotter pin into a spring retaining clip. Replaced coil that had been partially unwound (to increase strength and compensate for higher spring tension) with correct coil.

Replaced chrome legs with correct Bally-style dark grey legs.

Tumble polished:

Repainted:

Repaired / Reglued:

Other:

 

MPU repair - the battery damage was quite extensive, but everything works fine now!

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