OHMigod the coils!

[personalbest]

Hello good sirs, this is my first post.. I just added a seemingly good condition PinBOt to my collection. Played it at the location and it was a good solid player. When I got it home it played the same. Great, solid. Then, Pow! both flippers died at the same time having blown the 5a fuse on the flipper power supply board. Fuse was correct size and type. Inspection of the flipper coils revealed some very messy soldering which was even crossing from contact to contact on the switches and contacting the coil and coil bracket. Soldering issues and stray wires all corrected but it still pops a fuse when right flipper is engaged. Left flipper coil does not trip the fuse but is swollen and has no diode in the circuit. Any info on where to go from here? I was going to start by putting 2 new coils in and basically start factory fresh with both sides... New switches and diodes..sleeves, springs etc.. flipper switches.. What could possibly go wrong? no really! I want to know! Thanks, Jason

 

[Jay Walker]

HI, Jason

The flippers on an early 'System 11' game such as PinBot originally used serial-wound coils, the primary windings 23-600 (600 turns of 23 gauge wire) and the secondary or hold windings more turns of thinner wire, 30-2600 I think. These coils only have one diode, but it is essential, to absorb 'back emf' which if not restrained could damage electronic components, or cause strange effects. F'r instance, on the similar age game High Speed, a game in progress was spoiled when the displays, feature lamps and scoring simply stopped (Blanked out), though the background music continued, and the flippers were still On. Later, this game locked on a number of coils, burning them out along with their drive transistors. Simply due to the diode having broken on the upper flipper

I don't think there'll be any further complication for you, though. PinBot doesn't have solid-state 'FlipTronic' circuits controlling the flipper coils - all the current passing through the coils also passes through the end-of-stroke switches, cabinet button switches and the flipper relay on the main circuit board in the back-box. The relay shuts off the flippers when required by breaking the ground return for the coils

If you're planning to replace the flipper coils, you may wish to use the later parallel-wound flipper coils. The advantage with these is that it's practical to add a capacitor across the end of stroke switch to prolong the life of the contacts (much as a condenser was used with old-fashioned points & condenser vehicle spark ignition). You would then need new flipper baseplates too, though; the spur for attaching the switch is taller so that the condenser can be zip-tied in place. The later baseplates can be found with the spur spot-welded or detachable

 

[personalbest]

HI, Jason

The flippers on an early 'System 11' game such as PinBot originally used serial-wound coils, the primary windings 23-600 (600 turns of 23 gauge wire) and the secondary or hold windings more turns of thinner wire, 30-2600 I think. These coils only have one diode, but it is essential, to absorb 'back emf' which if not restrained could damage electronic components, or cause strange effects. F'r instance, on the similar age game High Speed, a game in progress was spoiled when the displays, feature lamps and scoring simply stopped (Blanked out), though the background music continued, and the flippers were still On. Later, this game locked on a number of coils, burning them out along with their drive transistors. Simply due to the diode having broken on the upper flipper

I don't think there'll be any further complication for you, though. PinBot doesn't have solid-state 'FlipTronic' circuits controlling the flipper coils - all the current passing through the coils also passes through the end-of-stroke switches, cabinet button switches and the flipper relay on the main circuit board in the back-box. The relay shuts off the flippers when required by breaking the ground return for the coils

If you're planning to replace the flipper coils, you may wish to use the later parallel-wound flipper coils. The advantage with these is that it's practical to add a capacitor across the end of stroke switch to prolong the life of the contacts (much as a condenser was used with old-fashioned points & condenser vehicle spark ignition). You would then need new flipper baseplates too, though; the spur for attaching the switch is taller so that the condenser can be zip-tied in place. The later baseplates can be found with the spur spot-welded or detachable

Thanks a bunch! I am really puzzled by the ohm ratings I'm getting on the coils.. I'm in 70+ ohms across high voltage coil and 4 (seems reasonable?) at the LV with the coil disconnected and diode snipped on the bench.