Common for this condition to be EOS related, either the contacts are not opening all the way or otherwise shorted. When the flipper button is held in, the EOS makes the low power high resistance side of the flipper coil do the work, and when working correctly you can hold the cabinet button in all day and the coil never gets hot. Hold the flipper button in and look for at least 1/8" gap at full flipper extension. Also check the big yellow EOS spark arresting capacitor to make certain it isn't shorted.

No, you will have to lift one end of the cap to get an accurate reading because it goes across the coils and diodes.

Check the power supply, especially 5VDC logic DC level and AC ripple on the +5VDC logic. Did the game reboot - or did you just get the start up tone and the game never rebooted? What I am getting at is this: there could be a loose/dirty cable connection between the sound board and the game. It sounds to me like the sound system is running the diagnostics mid game due to restarting from a momentary loss of power. Just a guess. This could also be causing hum (a "ground loop" situation)

I'm not at my game, my suggestion was to pull the power cable feed into the soundboard- see if you get the same symptom you experienced, where you get the tone but the machine never reboots. This might also happen with the ribbon cable as well. I'm pretty sure that is what will happen - but as I said, I'm not at my game to test this out. I know that the "bong" tone is an indication that the sound system has booted.

Right, the point was to pull and then plug in one at a time to see if you would get the bong tone. But now you have resolved that much.

What do you mean?

Tomcat uses D-11298 background sound and speech board. Is that what is installed in the game? Has the sound ever worked completely in this game?