Saw this in the System 11 Club thread. I guess I need to go through all the wiring and look for shorts.
Quoted from Tomass:
Ok, I see why I ended up with 2n5550's and not 2n3904's. The 11c board has the 2n5550 transistor on q42-q49 but the 11a has the 2n3904 transistor in that same spot. Seems like it is the same but higher rated voltage, but that is only from reading other posts. I would think it will work since it is in the 11c board and perhaps even an upgrade? Am I wrong?
Thanks for any input
Exactly. It's functionally the same transistor, but it doesn't blow up instantly if a higher-voltage wire accidentally touches its circuit due to a fault on the playfield. Just a little more robust, and a slight bit of insurance against ignorant folk working on the game with the power on.