Just picked up my first System 3 and am trying to troubleshoot several things - it powers on fine but when I open the coin door, all power is cut off...which I understand is normal because of the interlock switch. However, this makes troubleshooting via the switch/coil tests a real PITA. I know I can hold the switch closed while pressing the test button, but then I need a third hand to manually hit the switches on the playfield! What's the trick - just raise the playfield and close the coin door while performing tests??

I read that somewhere else...maybe I'm having a brain fart...but the interlock switch is already out when the door is open. Closing the door presses it in to turn power back on. From the other side it's a closed plastic housing. Maybe I need to look more closely at it.

Ok I had a chance to go look again ..duh...pulling it out is the answer although counterintuitive. Thanks for the help. While I'm at it...I have another quick question about troubleshooting a coil. It had a blown fuse so I replaced it. Haven't played a game yet as I wanted to further troubleshoot before activating power as I am assuming the fuse will blow again. Checked the coil lugs and they get power fine. Went to the transistor in question that controls the coil. Grounded alligator clips to the metal tab on Q12...and the non-working coil fired but I also got a spark at the transistor. Is this telling me I have a short between the board and the coil somewhere? Or something else? Thx!!

Thx for the help. I pulled the board - mosfet tests good. Board is actually very clean and has never been worked on.

I did find one mosfet that was bad for my left slingshot coil (which had a blown fuse and broken coil wire which I though was the issue but looks like that mosfet is the root cause on that). I'll test nearby resistors etc and see if I find anything....otherwise I'm thinking it's short somewhere under the playfield or the coil is wired incorrectly. It sucks not having the printed manual and looking at the drawings on my computer makes my head hurt!

Well..believe it or not...it actually "just needed a fuse" to fix it. LOL! Sweet! Left sling coil does need a new transistor but my original issue was just a fuse. Hard to believe but I'll take it. Game seems to working well otherwise...dirty as hell and needs some bulbs. Looking forward to getting the BIG HURT back in business! Thanks for your help.

Yep...I have several things I need from there for this game so waiting to order all at once for shipping.