Quoted from boneman91:Nobody makes an early System 11 replacement board and mine looks better than the "tested" ones I see for sale at shows.
I have reproduction / replacement boards for System 11 but it's only documented in my thread. I have not made them widely available but I do have them and they do work (there was one my friend with a High Speed was borrowing while I repaired his board).
Quoted from boneman91:My right kicker coil on my System 11 Road Kings locks on when I enter test mode, as well as when the game is started or any time power gets to the coil.
If the solenoid locks on immediately at power on then the transistor is shorted. If the solenoid locks on when starting a game (or entering diagnostic tests) then suspect the path where the logic from the software and the hardware merge at the digital logic level. You should exclude the switched (special) solenoid switch. Disconnect 1J18 and repeat the tests. If the solenoid still locks on then the problem is likely in the digital logic side (upstream from the drive transistors). If the solenoid does NOT lock on then it's likely to be a playfield switch problem. Always consult the schematic in the manual for confirmation.
Quoted from boneman91:I Replaced the Q71 transistor. Problem recurred. Sent the board out for repair, came back with a clean bill of health, and problem recurred. Tried replacing Q71 again, still locks on. I've replaced the coil. I've traced both the power and return wire, can't find any issues.
If the solenoid diode has failed you will continue to replace the transistor until you replace the diode. The diode stops the back EMF voltage spike that causes the transistor to fail.
