Fixing Flippers 101

 From: musjndx@gsusgi2.gsu.edu (Jonathan N. Deitch)

Subject: Fixing Flippers 101 (was Re: Flipper Help)

Date: 29 Aug 1994 20:21:22 -0400

Argh ....

Fixing Flippers 101 :

A flipper works by pulling a metal shaft along a sleeve inside a coil.  As

you don't want the shaft exiting the other side of the coil, there's another

piece of metal to stop it.  After thousands of flipper presses, these two

pieces of metal eventually get flattened and the tips begin to spread out.

This is called mushrooming.  It causes fricting against the sleeve resulting

in a weak flipper.  Eventually, it will wear right through the sleeve and

start tearing the inside of the coil apart, usually resulting in a shorted

coil and often a complete meltdown of the coil's interior.

Symptom : No flip.  At all.

- Check the fuse.  If it's good, make sure your main 50vdc power is getting

  to the flipper (check the manual for the proper wires to check).  If it is,

  make sure your flipper cabinet buttons are okay.

- Fliptronic systems on WPC games have coil tests specifically for flippers.

  This helps you identify what coil is the problem.

- Still no go ?  Remove the coil, unsolder its diodes and check for continuity.

- Still no go ?  Follow the circuit from the transformer right on through the

  power supply until you find the point where it stops.  That'll be the problem.

Symptom : Weak flip.

- Likely this is a worn out EOS switch.  The power coil is permanently dis-

  engaged from the circuit as the EOS isn't conducting.  Replace the EOS and

  see if it helps.  If not ...

- Check the plunger shaft and coil stop for mushrooming.  Replace if they don't

  go in and out of the coil sleeve freely and cleanly.

Symptom : Flipper Chatter

- Broken holding (low power) coil or bad low power driver on a Fliptronic board.

Symptom : Stuck flipper

- EOS paw on crank has a worn out rubber sleeve.  This can etch a hole in the

  EOS switch in which the paw gets stuck.  Put a new piece of 1/4" heat shrink

  on the paw and replace the EOS.

- Flipper crank tightened too tight on shaft.  This causes excessive binding

  between the playfield bushing and the crank assembly.  There should be around

  1/32" (enough for a slight wiggle) of a gap.

NOTES :

=======

Whenever a new game comes into my store, I always replace just about everything.

This is because I've found most other places don't ever check flippers and

end up turning 'em into junk.

I replace : Coil stops, Coils (if worn out), Coil Sleeves, Cranks, Crank Links,

Plungres, EOS switches, paw rubber, et al.

Coils don't need replacing if a new sleeve can easily be slid in.  Otherwise

it's expanded from heat and will cause a new plunger to bind.

Fliptronic boards use a standard driver chain similar to the WPC power driver

solenoid drivers.  These *can* blow, so make sure they're okay.

Opto driven flipper switches are run my LM339 voltage comparators.  If either

the opto or the comparator aren't working properly, you can have a weak flip,

bad EOS hit, both or none.  If everything else has been replaced, this is

likely the fault.  Switch the opto boards (the left and right ones are 

interchangeable) and see if the problem follows the board.  If not, replace

the LM339 that drives that opto.  Note that both opto boards must be plugged

in for either of them to work ...

NEVER EVER EVER oil, grease, lubricate or do ANYTHING to a flipper plunger

or coil.  Same for standard soleniods.  The action of the plunger rubbing

against the nylon sleeve creates a natural graphite coating that acts as

a lubricant.  External lubricants attract dust, metal shavings, pieces

of solder or wire or whatnot.  These get down inside the flipper and cause

all kinds of hell.  Don't do it, or you'll be replacing the plunger, coil

sleeve and maybe the coil too.

- Jonathan