I've been tinkering again lately with the pin. I pulled the driver board last night, and discovered some problems. First, some background info:
The sound died off last time I messed with it. I had no clue why. I pulled the sound card, and the power caps have scorching near the leads. These sound boards are pretty much never supposed to go bad. I now have the sound card pulled. I'll follow up in a minute
Anyways, I pulled the driver board becaue I knew I had at least one bad lamp driver. I found two bad lamp drivers, then noticed a TIP100 down at the lower right that looked like a dead, bloated fish. It was the knocker coil transistor. I remembered that I had never heard the knocker before, but also noted that this transistor didn't look like that when I originally got the driver board. I replaced it, then went and checked resistance on the knocker coil. It read 12-13 ohms, so I assumed it was good. Anything around 3 or less is a shorted coil.
Thinking everything was kosher, I put the board back in and fired off a few games. Oddly, the knocker coil started firing sporadically. The efforts seemed half-hearted too. It stopped, and I finished testing stuff out. Noticed a ever so slight burning smell too. Anyways, the knocker coil assembly is super hot to the touch, and the newly replaced transistor is super hot too. The coil did not appear to be locked on when I looked at it a few times. Looks like I need to check a few chips on the CPU.
Back to the sound card. It is relevant because the sound card pulls the 24V directly from the power lead of the knocker coil to create its lower voltage requirements. If the knocker coil is ---smurfing--- up, then it could have easily wiped out the regulator circuit on the sound card, I think. The schematic shows the 24V coming in to a Zener diode, then hitting the scorched 500ufd filter cap, then a larger resistor.
I guess my question is about the coil. Can a locked on coil still be in the "deengergized" position? Can a coil showing 12ohms still be a bad coil? I am kind of stumped in this respect.