I developed an unusual problem with my Abra Ca Dabra: There are many items on the playfield that score 500 points - rollovers (which don't complete the sequence) and drop targets that aren't lit. 90 or 95% of the time, those items score correctly. But occasionally, instead of scoring 500 points, it may only score 300 or 400, and followed by the sound of a buzzing relay. At that point, if I hit any 500 point target or any rollover, it scores nothing. If I hit a lit target, it will score 1000 (or whatever the bonus value is) and that usually stops the buzzing relay.

Investigation has determined that buzzing is the M (100 point) relay in the backbox. When the problem occurs, that relay remains energized and won't release until I push the armature away with my finger.

I know that 500 points are scored in 100 point increments - so when the 500 point switch is closed, the 100 point relay will receive five pulses from the score motor. But when the problem occurs, only three or four of those pulses seem to go through (although the score motor turns the correct amount) before the relay stays energized and locks up.

I've cleaned and adjusted the switches in the M relay to no effect. I even took the relay apart and cleaned the armature (I had a stuck relay issue with Sure Shot and that was the solution as seen here: https://pinside.com/pinball/forum/topic/gottlieb-sure-shot-bonus-count-issue-#post-6084166). But that hasn't fixed the problem either.

Any suggestions?

Here is the relevant portion of the schematic.

AbraCaDabra Schematic 500 pt (resized).jpg

I would think if it was magnetized it would happen more that 5% (rough estimate) of the time.

LTG - you got me thinking:

MarkG suggested a way to test when I had my Sure Shot issue.

"A bulb tester would confirm whether or not the Z relay is sticking on its own. You could connect at 6 volt bulb (e.g. a #44 or #47) across the Z relay coil solder lugs and then watch to see if the relay is ever active when the light is off. Or you might unplug the game while the Z relay is on to see if it stays on.

If it stays on without power the relay may be magnetized. Is there a brass washer between the base of the relay coil and the relay frame? And is the coil mounted to the frame with a brass bolt?

/Mark

Let me check and see if it is holding on it's own or if it's getting juice.

HowardR - THANK YOU! You were absolutely correct. The EOS switch on the 100 score reel was not opening completely. I cycled through it a couple dozen times and for whatever reason, there were times when it did not push the contacts apart enough. So I adjusted the switch to make certain it would open it wide enough every time and now it's working fine.

I've posted some photos in case any one else comes across a similar issue. The first photo shows the switch in normal (closed position). The second shows it in what's supposed to be open. The last one shows the adjusted switch in open position.

Score Reel EOS Switch_Closed01 (resized).jpg

Score Reel EOS Switch_Open01 (resized).jpg

Score Reel EOS Switch_Open02 (resized).jpg