I finished a top to bottom restore of my Slick Chick early this year. It seemed to work flawlessly except for one nagging intermittent issue that was annoying. Occasionally after a couple of games the pop bumpers would stick on intermittently, occasionally going off after I hit another bumper but usually forcing me to switch off the machine to reset the game.

I filed or cleaned over and over again all the relevant switch contacts on all associated relays and on the scoring relays and it seemed to improve things for a while, and this stopped the game freezing with a relay locked on. However, a bumper relay would still occasionally stick on momentarily going off only when I hit another bumper. I must have lifted the playfield 50 times since trying to find the root cause. No other game I have had this issue. I started to look for a magnetized coil plunger and studied the schematic trying to see a hidden connection between the bumpers and switches etc. I never found a suspect switch that explained what was causing this issue and never found a coil with a sticking plunger until yesterday! It wasn't residual magnetism but a mechanical fault.

The 0-9 stepper has a connected 3” bell to signal scoring 1 point. As you score points it hammers that bell as the coil plunger pulls in.
0-9 Stepper as mounted. (resized).JPG 0-9 Stepper with bell

This I thought was a cool stepper that is held parallel to the mounting surface with 3 pins as it allowed you to mount it quickly. Because it is not perpendicular to the mounting area you cannot see the coil activating only hear it work because of the bell this is not so cool after all.

I unclipped the stepper and was watching the coil activate as I kept closing the N relay (yes, with the power on). The coil and plunger was chattering and seemed that this might be causing the issue…and it was. What was happening was the bell striker was too close to the bell so as the stepper coil pulled in the plunger, the coil plunger never reached the coil stop. The striker hit the bell first, not releasing the stop and deactivating the N relay EOS switch every time. There is also an adjustable stop and it was not adjusted correctly either. The fix is so simple, re-adjust the bell position away from the striker.
0-9 Stepper (resized).JPG Adjusting the bell and coil

I have never seen this issue mentioned in any search before (I made many searches here, on RGP and google) as it is probably so simple to so many it doesn’t need documenting. Anyway if others make my mistake hopefully you find this explanation a lot quicker than I did.

Rolf,
I think you are over thinking it. It was a bell that was too close to the striker on the stepper. I will remove the offending word 'sometimes'.

It doesn't.

This was a mechanical issue not an electrical issue.

From the second picture the striker is attached to the arm with the coil plunger. The plunger on the 0-9 stepper is activated by the N relay that registers a 1 point score from the bumpers and the kickers via the advance unit. So when the plunger pulls in it could not bottom out on the coils stop as the striker hit the bell first. This makes the plunger for the want for a better description stutter. Once I pulled the bell away the stutter stopped and the issue went away. After a while I adjusted the bell closer to the striker and all is well.

Causation I suffered was the bumper stayed on momentarily and the hitting of another bumper seemed to release it. I am guessing the power was not released when the coil plunger chattered not letting the bumper relay or relay N to open.

The N relay did not stutter it stayed full on along with the pop bumper relay on the play-field, the stepper coil plunger stuttered or chattered.

If you want to recreate the issue move your bell closer to the striker so the coil stop on the stepper fails to reach the stop and see for yourself.

Steve.

That schematic snippet looks similar to the Slick Chick.

Why are people looking for an electrical solution to a mechanical fix? I did that for most of the summer as I explained in my original post. It really was the bell position!

Regards Steve

That is correct.

I was not smart enough to find it for a long time as I did not look outside the box but if the stepper had of been perpendicular to the light box I would have seen it much sooner. LOL

This is correct as Woz also stated.

But you guys are being perhaps ....a little obtuse in your statements. If you look only for an electrical issue you can't solve this problem right? Why? Because its a bloody mechanical issue!

Anyway moving on I am a mechanical engineer not an electrical engineer so learning about electro simple EM circuitry I researched can be found in lots of places but have you seen this booklet put out by Williams in the late 60's early 70's.

http://backglass.org/williams/kordek_archives/introduction_to_coin_operated_amusement_games_wms_100.pdf Duncan Brown posted the link on RGP last year.

Its a nice handy-man book that explains circuitry and has some nice info that can help pinballer's trying to read schematics and understand what you are seeing in all EM's. It is simple and correct.

What more do you need to know about the electro side of an EM machine.

1a Undestanding Schematic Circuits (resized).JPG
1 Circuit Types (resized).JPG
3 Circuits (resized).JPG
4 Troubleshooting (resized).JPG
5 Trouble shooting example (resized).JPG
6 Troubleshooting example (resized).JPG
8 Safety (resized).JPG