Ghost in the pop bumper

[joele]

OK been taking the playfield in and out a lot on my RFM, and must have done something bad to it?

One of the pop bumpers is randomly firing by itself, does not seem to be linked to anything in particular, like the flippers, in fact can just have the ball ready to fire not even in play and it still happens..

Tried spreading the switch so it now doesn't even fire if you trigger the bumper, but still fires randomly, and when it does it doesn't affect the score.

any ideas?

[robm]

Maybe the drive wire for the coil is grounding somewhere, look for a pinched wire, or small bare section of wire.  Prob best to trace it back from the coil itself.

[joele]

Think I might have found the cause, can't test yet as machine is pieces, but the stupid wire/metal strip from the light in one of the other pop bumpers was touching the base of the switch for the ghosting pop bumper and I wonder if that could have caused the issue? fixed and will find out I guess when I finish rebuild..

[joele]

Well the problem above wasn't causing it (light wire shorted on holder)..

Really at a lose here, replaced with new switch and coil (just in case), traced wires back from coil and can't find a pinch or bare spot..  

[joele]

FWIW, problem now solved...

After exhausted all my and the forum ideas I called Chris (pinball medic) who luckily lives near to me, he came around last night with schematics and worked out it was two of the chips on the driver board that were connected to a particular row on the play-field that were playing up. Was triggering targets as well as making the pop bumper coil go nuts..

Chips switched out and all perfect now.. Seems there was previously a lot of work done on the board, more than he had seen on a p2k board before, but all cleaned up and working now.