Repair 1b - Star trek STTNG bottom diverter coil burning up
So my nightmare with STTNG is not yet over. Just as I finish my previous repair on the dead left popper coil, I go to test the game and notice the rear drop target is dead. Odd, it was just working. Back to the test menu and run through the solenoid tests. All the upper coils are dead. Time to check the fuses.
I check fuses, and F103 is blown. Pop in a new fuse and give it another go. Fire up the game, close the coindoor, watch the drop target work, and start a game. Not a few seconds later I smell smoke and F103 is blown again. Turns out the bottom diverter coil is melting.
Power off the game, remove the coil. Now to do some testing. I replace the fuse F103 again. I clip the wires off the burnt coil. I have to replace the coil anyway at this point. While there, I test each of the leads to see if any are grounded. A grounded transistor would cause the coil to lock. So I put my meter on the black wire and the other end on the ground braid. It's a short. This is why my coil was locked on.
I look at the coil chart in the backbox. I notice this coil is on the aux board controlled by J4, pin 4 and Q15. Q15 is a TIP102, so it's easy to test if it is shorted. (A shorted transistor will blow your fuse and lock on your coil). So I test Q15 by putting my meter to continuity mode, one lead on the tip of the transistor, the other on ground. It's shorted. Time to replace the transistor.
I pull out the aux board. Look on the back and OMG is it hacked up. Looks like some Neanderthal was using it as a soldering test station. No way do I want to risk soldering on these board parts again. So I add to the hack. I cut off the old TIp102 and this time I solder the new one directly to the old legs of the one I cut off. I hate doing this, but this board will not survive more flowing of the traces and holes.
Pop the aux board back in, hook everything up, and we're all working again.