Some strange things going on with a Bally Paragon I'm working on. Bottom Pop bumper wasn't working so I figured its either a switch issue or transistor on the board. Pop bumper switch seems fine, it scores but doesn't pop. Grounded the Transistor on the board and it works. Figured it was a whacky transistor so I replaced it with a new TIP102. put everything back together still doesn't work. HERE IS WHERE THINGS GET WEIRD... Once I ground the transistor out on the board, the pop bumper starts working for a while on its own, almost like it got jump started??? It stops working after a few games and goes back to just scoring.

Any suggestions or theories on this little odd behavior?

Interesting, ok I will have to see if I can replace that associated chip - is the diode worth messing with first or should I go straight to replacing the chip?

The solenoid never locked on - its basically locked off, until I ground it out, then it works for awhile and goes back to not working. Yep no problem doing the chip soldering, got my Hakko desoldering gun.. woo woo.

Im leaning towards it being the chip just seems so strange to me that it would work after you ground it out and then suddenly stop after a game or two, then you ground it out and it works for a bit again. Diodes usually are either good or bad and same with transistors, never had one sometimes work.. I'll let everyone know what I find out.