(Topic ID: 285669)

1964 Williams Oh Boy pop bumper issue

By SuperSpinhead

2 years ago

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#1 2 years ago

Hi all. I greatly appreciate any help that you can give me. I'm not an expert but am learning and can fix some stuff. So I brought this machine back from the dead and have everything working except for one red pop bumper (lower left on schematic) which scores fine from the spoon switch but won't pop (Note - there are 2 reds that fire together in series that are the upper right and lower left in the schematic). There are also 2 greens upper left and lower right. I'll try to make the issue clear.

I found 2 problems: 1) broken e.o.s. blade on the right side green pop bumper which I fixed/replaced.
2) The e.o.s. (or what the schematic calls "lock switch") contacts on the reds are OPEN but SHOULD BE CLOSED. However, when I close them
and start a game and hit either red bumper the upper right will pop and lock on/freeze/buzz. All the coils seem fine with a multimeter but
I have not been able to get the lower left to pop, so I am questioning the coil there.

Before I remove that coil and test/re-solder/replace it I'm wondering about the THIN GRAY WIRE that connects the lower left bumper coil lug to the Number 1 bumper relay...the gray wire then continues over to the Number 2 bumper relay. FYI - the red bumpers feed to the No. 1 bumper relay and the green to No. 2 relay.

IS THAT GRAY WIRE FROM LOWER LEFT RED POP BUMPER COIL LUG TO NUMBER 1 COIL RELAY SUPPOSED TO BE THERE? ...did somebody jump that to try to fix a problem? I'm hoping that the answer is easy for the experts here. I know that manufacturers are different but my 1964 Ship Mates has a similar 4 pop bumper layout (2 and 2) but doesn't have that extra wire from a pop coil lug to a pop relay.

What is strange is that the upper right coil fires/pops although the end-of-stroke switch is OPEN when it should be closed. As long as I keep the red bumper e.o.s. switches open I can play the game except that the lower left red pop bumper won't pop, but will score from the skirt to the spoon switch.

So before I start playing with the lower left coil or removing any wires I wanted to ask the forum.



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#2 2 years ago

Power is sent to the bumper solenoids (pop bumpers/jet bumpers) through switches on the bumper relays. Check the switches on the bumper relays to see if they are clean and adjusted properly. The switches on the bumper relays need to open and close at the "exact" same time. If they're not adjusted correctly, then the playfield bumpers can lock-on or not work at all.

The gray wire should be like a ground wire for the coil. Or it's a jumper wire for the ground. Check the solder joints to see if they are original or if they have been re-soldered. The schematic will also show the wire color for the wires connected to the bumper relay coils.

#3 2 years ago

Fred, thanks for your reply. You da man! A bumper relay was not making contact on activation so I adjusted it and now that red bumper pops. But what I don't understand is how a jet pop bumper could still pop when the e.o.s. switches are open!?....Could that be because of the gray wire that connects both bumper relays? I closed the contacts since they are supposed to be closed.

The only thing that I notice now that wasn't happening before is a slight buzz that happens only when a different bumper is lit and activated...I'll give you more context: besides the 4 green/red jet bumpers there is a line of 5 yellow bumpers that sequentially light up for 10 points (instead of 1 point). When a specific one of those bumpers is lit and activated it buzzes faintly until the next bumper in the sequence (which is now lit) is activated, at which point the buzz goes away....until you progress once again through the sequence and the same bumper is lit and hit. When I put glass on and close the machine I may not hear it but I know that it is there. Other than that buzz there aren't any playing issues at present. This is a first for this machine. Thank you so much.


#4 2 years ago

Apparently the buzz was from the relay that gets activated and stays on when the bumper lights up and stays lighted until it gets hit again. I jiggled the metal activator plates on the relay a little and that seemed to stop it.

Fingers crossed since everything works. Now can move on to cosmetics.

Thanks again.

#5 2 years ago

Buzzing relay coils are pretty common on EM pinball machines. Clay's Pin Repair Website has some good information on the subject:


#6 2 years ago

Thank you!

#7 2 years ago

The EOS switch generally is used in series with a lock-in switch on the jet bumper relay, to ensure the relay stays energized long enough to achieve a full stroke of the jet bumper solenoid. Otherwise, if the ball just momentarily grazed the jet bumper skirt, the jet bumper relay might not stay energized long enough to achieve total function of the jet bumper. The opening of the EOS switch is designed to terminate the locked-in state of the relay.

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