I am having a flipper issue with a Bally solid state Freedom. The right flipper has gone crazy on it, activating on its own, sometime working fine and sometimes staying energized whenever the relay on the solenoid driver board closes during the MPU test on boot up and as soon as a game is started. It can be energized and the go back and act normal without me doing anything to the pin. Sometimes it will go into full auto fire mode and repeatedly Fluttering up and down like a bad hold coil without ever hitting the flipper button. The left flipper is completely normal.

Other observations.

If I measure the resistance between any flipper coil lug to ground, the resistance does not change whether I hit the flipper button or not on the left flipper, measuring approximately 530 ohms. If I do the same on the right flipper when it is acting normal I get the same results, no change and about 530 ohms. When it is acting up, the resistance drops in half when I push the flipper button. I was able to repeat this measurement several times with it acting up and acting normal, always with the same results.

There is good continuity between the common wire between the flipper coils and the flipper power return (ground) on the transformer board. There is also continuity between the flipper power on the solenoid driver board and the flipper switches.

With the flipper acting up, if I measure continuity across the flipper switch I get 1200 ohms. If I disconnect the flipper return at the transformer board it goes to infinity. If I disconnect the switches at the solenoid driver board I still measure 1200 ohms. I measure infinity across the left flipper switch. I tried to get the right flipper to act normal again so I could measure the resistance across the switch, but it was not cooperating.

I replaced the coil in case somehow it was shorting to ground and activation the flipper or in case somehow the diodes were causing the issue. I also disassembled and cleaned the flipper switch in case there was a metal shaving shorting out the leafs of the switch.

All resistance checks were made with power off.

It seems the right flipper has become possessed. Sometimes it with flutter at a high frewuency and then all of a sudden stay up without any flipper button action. Then suddenly the flipper will drop and act normal with the flipper button. I placed the pin at a retirement home on free play for residents enjoyment. They played 600 games in two weeks. I hope to quickly get it working for the residents again and appreciate where I should investigate next.

Thanks in advance.

Carey

Thanks for the responses so far.

It seems to me it wouldn't be the flipper return wire because if I disconnect it at the transformer board, it goes to infinity. But I will try it. I thought about replacing the wire from the flipper switch to the solenoid driver board, but that would short the power, not ground the circuit. Also the flipper return is common for both flippers.

Pulled the playfield out and examined the wires. I didn't see anything adnormal so I metered out the wires while wiggling. Didn't find anything. Pulled the driver board to see if something was shorting to ground on the back and didn't find anything. Put it all back together and it seems to be working fine.

Maybe I exercised the ghost.