Location: Centennial, CO
Symptoms: Flipper problems.

The owner previously knew the lower right flipper coil was bad, so I had a replacement on hand when I arrived.  After replacing the coil, I checked all of the fuses on the Fliptronics board and found one blown and another fuse as the wrong value.  All four fuses should be 3 amp slo-blo (MDL type).

I powered up the machine and found that the flipper was often sticking in the up position.  Before the coil went bad, this was one of the original complaints.  It wasn’t a mechanical sticking, but the hold coil was staying energized when it should have released.  I tracked the problem down to the flipper opto board.  The bottom edge of the board wasn’t was tightened down all of the way.  The board was just twisting enough that it would move slightly when the flipper button was pressed, then it didn’t detect the button being released until some vibration in the machine caused the board to move a little.  I tightened the mounting screws and that problem was solved.

The upper right flipper was kicking but not holding.  It looked like all of the wires were connected to the coil and the terminals were wrapped in electrical tape.  So I looked at the Fliptronics board and checked the voltages coming back from the flippers.  When the game is powered up, in play mode, and flippers is NOT energized, 70 volts should be present on every terminal of J902 that has a wire connected to it (it varies from game to game based on the number of flippers).  This is a good way to check coils and connections.  In this case, there was no voltage present on pin 4. That verified that there was an open connection in the coil or the wiring.

So I went back to the coil for a closer look. I unwrapped the tape and found that the terminal strip on the end of the coil bobbin, where the connections are made, was broken.  It was the reason why it had been taped. The fine gauge wire used in the winding of the hold circuit had broken inside the coil.  Some coils can be repaired if the broken wire is on the outside layers of the coil, but in this case it wasn’t.

I generally don’t stock flipper coils, so I would have needed to order it. The owner elected to buy a new coil at the Pinball Showdown, which is happening this weekend in Denver.

Not all flipper coils are created equal for the Williams pinball machines.  Each pinball machine was designed to use specific coils based on what the coil needed to accomplish in each game layout.

• FL-11753 Yellow – Used with short flippers and close shots
• FL-11722 Green – Used for close shots near drop targets
• FL-11630 Red – The standard, most commonly used coil
• FL-15411 Orange – Used for long playfield shots
• FL-11629 Blue – Used for long shots and high ramps

In the case of White Water, the blue coil is specified as the lower right and the red coil is specified for the upper right.