I am looking for ideas. I just bought a twilight zone the lower jet bumper is not working. Upper bumpers work. At coil I have 70 volts at each prong which indicates I have power and I believe coil is good. Power board is rotten dog replacement. Q52 transistor test good. No errors reported by game. When I test nothing happens. When I test Switch it works. I am out ideas. Should I try swapping coils to make sure coil not bad. Should I replace transistor ?

i believe it is q52 which is the solenoid 12 circuit. I check connectivity of the wire running from coil to 127-5 connector to board. It appeared to be good.

When I check connectivity of wire I did reseat the J 127 connector. No luck. The transistor is a TIP102. I did not ground when machine was powered on. I did when it was off. There was no connectivity which I believe indicated transistor is not shorted out. Coil is not engerizing at all so not surprise by result. I am apprehensive about completing circute when powered on as it is 70 volts DC. Is there a way to test pre transistor. Is there a way to test address decoder (never heard of that) Board is a Rotten Dog after market so I assume it is good

thanks for everyones suggestions when I get home from my current business trip I plan to test the coil and transistor as suggested above.

Update. I grounded the q52 transistor and the bumper coil energized and did not shut off. I called Jim at Rotten Dog to confirm what transistor was on the board. I am glad I did Jim was extremely helpful. As it turns out transistor was not a TIP102 it was a IRL520. There are no pre transistors on the board so that is all I have to replace. Jim suggested I replace coil as that might have caused the issue to begin with. Better safe than sorry. So I order transistor from great planes electronics. And coil from marco specialties.