I have been working on a Space Invaders for a while.
At first none of the solenoids worked (everything else seemed to work). I did a lot of testing and cleaned the molex connectors but nothing seemed to work. The fuses were ok. Suddenly, when I measured the voltage on one of the solenoid board test points (TP5 or TP3) the solenids came alive! How can this be explained?
The right thumper bumper solenoid still doesn't work. I have measured all three bumper solenoids and they are about 12 ohms each. The right bumper moves as it should and the score/sound is activated when the bumper is hit by the ball (so, there is nothing wrong with the switch). Any suggestions what might be wrong here?