I'm fixing a space shuttle for a friend and I'm a bit of a newbie on pinball repair, I've only ever restored arcade games before this. The single drop target for "T" that blocks the multiball ramp is not working. I followed the troubleshooting guide I found online for Williams system 9 and the coil tested good, the diode tested good. I then did what the guide said and shorted the collector leg for the transistor to ground and that did fire the solenoid. After that point the guide just says "Check the rest of the circuit" Being a controlled solenoid the rest of the circuit seems to be another transistor and a 7408 "and" gate. Not really sure what to check and what I'm looking for, for all the other tests the guide is straight forward as to what you're looking for (voltages, pulses etc.) but for this it just says check it. Anyone have any experience with this sort of controlled solenoid on system 9?

Thanks.

Its supposed to engage the solenoid to pop up the target when the game starts, after you hit it, it pops back up after a certain length of time or when multiball ends. The target registers a drop (The switch underneath is fine) but the game doesn't pop it back up during game start or any other time (I've manually popped it up and triggered it to see).

I'm confident I can do the board work, just wanted to be able to test the parts. I do have a logic probe and used it to check the memory protect circuit as it was stuck on, just wasn't sure what I was looking for it regards to readings. You're right, if that will fix the problem I guess I can just replace both parts, add in a socket for the 7408 as well.

Perfect thank you, I'll check that out!