A shorted transistor or a shorted pre drive transistor(the smaller one)And diodes on the coil if there are any.Also the coil if it is fried,Coils very seldom ever go bad but it would not hurt to test that coil.

Diode tie back wire broken off of drop target up coil.

One lug has three purple wires with green stripe. ( one is kind of a lavender color, thinner, green stripe ) When the lavender color one breaks off, you blow up all kinds of cool sh*t.

I would remove the three wires from the lug. Solder them together and to a single wire. Heat shrink this. Then the other end of the single wire I would solder to the coil lug.

This way if the wire breaks off the coil. The only thing that happens is the coil doesn't work. No more blowing up cool sh*t.

LTG : )

None on this coil.

LTG : )

Try reversing the the ribbon cable between the MPU and AUX driver board on both ends so that it uses different wires for the data and clock signals...if this helps, you have a bad cable.

Other thoughts ... verify that this cable isnt backwards on one end to start with befoe reversing it.

Not sure whether to call that progress or not

F103 Powers your 20V flashers and should have nothing to do with your diverter coil;however, this voltage also goes to aux driver board to power your Right Ramp and Romulan flashers. The aux driver/data lines may be a common problem here. Did you verify that the data cable is properly positioned with the red stripe on the bottom or MPU J211 and on the left side of the Aux driver J1?

Because it locked on, and got hot. They're not supposed to be activated continuously at full power.. now you get to replace that coil again.

You said you replaced the PRE-driver transistor? How about the primary? (oops, I saw you said you did that in the original post) Did you replace them at the same time? Otherwise you may have just screwed the one you replaced as well. I've *never* had to replace a pre-driver, but I've replaced a bunch of the main ones right before the coil. But when you're blowing full collapse voltage back into the system, no telling what or how much you're going to blow up..

*Edit* For that matter, have you taken apart the diverters and cleaned them? All of the diverters on STTNG are NOTORIOUS for getting gummed up, so even if you "fix" the problem, they may not move correctly!

At this point, I would....but you melted a sleeve into the coil already, so it's a moot point. I wouldn't replace any diodes on the PCB unless you're super comfortable with soldering and/or you've already tested them and they're broken in some way (Exploded, caught on fire, allowing current in both directions or NOT allowing current in the proper direction. You'd have to test that when the driver board is out of the game anyways.). You have to replace that coil and assuming you're purchasing the correct part it should have diodes on it, but I'd be real sure to check the orientation is correct and use your meter to make sure it only allows current in the correct direction BEFORE you solder it in. I've bought coils before that were missing diodes or they were mounted backwards.

Okay, gotcha. It's been a while since I had a STTNG and I never had to do anything with the aux boards, but I'm pretty familiar with WPC in general.

That's because the diverter isn't working for whatever reason. Checking the optos on the underside of the subway is a good idea. Suspect one is the one at the "top" of the subway for the scoop behind the drop target. This the same diverter that had the melted sleeve? Heh.

Check for 12V on the 16 opto board on the underside of the playfield.

That's one way to go; in absence of meter, that board does have an LED to let you know if it has power.

Awesome, nice work. The good thing about STTNG is..at least in my experience owning two of them, generally once you get past the drop target and diverter issues, you've bascially fixed the worst of it! Everything else is really accessible and makes sense, but the logic for the diverters and optos is a bit wonky at times. Any one of those not working 100% (and the cannon optos too for that matter) can cause really odd things to happen.

This drop target should be up everytime a new ball is in the ball launch mech, if you chose to lock a ball the game lowers the drop so the ball can be fed into the top subway hole and on to the upper left VUK (no-energized diverters). The game can get get confused and exhibit odd behavior if the drop target isn't functioning properly. When the game reads "ball in launcher" I believe that game then performs a DROP TARGET check to see if drop target DOWN switch is closed and only energizes the RAISE coil if both switches are closed at the same time.

Please make a new post for this issue as it could take trying a lot of different things before finding the problem. Since you recently worked on the PDB, you will want to take a very close look at the repair work you performed on the 5V section...especially if it wasn't resetting prior to being worked on.