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Last modified October 2, 2023

Gottlieb Pinball Troubleshooting - ElectroMechanical games.

Gottlieb Electro-mechanical (EM) games (relays...)
Re: EM: Gottlieb Drum Unit problems 
Gottlieb Fast Draw not resetting properly ; most EM pins 
Setting up EM Drop Target banks
Understanding the Player Unit
Free "COIN" play
Where to press up (48420 bytes) To get free coin play on Gottlieb pins you need to open the coin door, then stick your finger under the coin mech. support frame and push up. Here is a picture of the inside of the coin door with the coin mech. in place, and here is the same finger with the coin mech. removed.
Setting Gottlieb Flippers (EM and Solid State) correctly
Blow-up of a correctly adjusted flipper pawl (31364 bytes)
I have often found poorly adjusted flippers on Gottlieb pins, the typical symptoms are; weak flipper, and slow or sticking flipper return. the cure is to make sure that after you have replaced the flipper coil sleeve, and fixed any other issues is to make certain that the flipper pawl is centered between the two nylon bushings. This is very important to good flipper action!
Electro Mechanical: Gottlieb Drum Unit problems

TO: All

Spotted this...
 GG> From: (Gil Graybill)
 GG> Date: 21 Nov 1995 21:59:29 GMT

 GG> Some questions:
 GG>    (A) About 90% of the time when a 50-point award is to be given, it's
 GG> worth 60 points. Can I do anything *reasonable* about this, or is that
 GG> just something that 30+ year old machines will do?

Check for switch bounce on the timing motor and that the break contact on the
drum unit is opening just before the plunger bottoms out. You might also have
a ratchet spring on the drum unit that is not engaging the underside of the 
number drum. make sure that it is bent out and snaps into the stepped ratchet
on the under side of the number drum. I don't think I can draw that in ASCII
but I'll try....
Drum unit ratchet spring
 Note that I have left out the solenoid, springs, drive ratchet assembly and
other stuff (you try drawing it smarty ;-) 
Hope this is clearer.....
Gott Drum Ratchet Spring adjusted correctly Note the ratchet blade is straight with a small bend on the end to engage the underside of the drum.
Drum Ratchet Spring Engaged under drum When installed the tip of the spring engages the ratchet under the drum so the drum will not turn backwards when stepped.
Gottlieb Fast Draw not resetting properly ; most EM pins
To: All

Saw this the other minute...
 m> From: (mark)
 m> Date: 11 Jun 1995 01:16:53 GMT

 m> I own a 1975 Gottlieb pinball machine titled Fast Draw
 m> It is a four score machine.  The machine is in excellent condition.  
 m> Everything works just fine except it does not give me my 
 m> bonus score.  I think because of this it will not indicate 
 m> game over.  Both of these problems are intermittent.  

With most EM games of any vintage, when a symptom of slow or intermittent
operation shows up, first check the operation of the step up/down units
that control the counts for Bonus, Ball, Player, etc. You will usually find 
that some misinformed person (read idiot) has used WD-40 as a (ha) lubricant
(double ha). The problem with WD-40 is that after a couple of years it turns 
to glue. The moving parts must then be removed, soaked in varsol, polished
and then reassembled using a good grade of oil. I use Zoom-Spout, but bicycle
oil or sewing machine oil will work fine. Easy test is to operate the step-up
plunger, it should snap back solidly with a solid thunk sound. The surface of
the contact discs can be greased with coin machine lube or a light grease (any
suggestions? as I use coin machine lube) I would like to try something like 
Vaseline as I hear it's quite good as a grease (not the VapoRub stuff!), but
haven't had the time to evaluate it properly.
(update 2006)
Hi. Just began reading your informative web sit. Two things.

First, I have read that using vaseline petroleum jelly is a terrible
lubricant for the very few parts which we lubricate on pin machines. It
turns hard later. Best substance for lubrication is electronic teflon lube
gel, which is available at Radio Shack, etc.

This gel is excellent for these few areas of lubrication.

Second, I believe the teflon lube gel is ideal for steppers as well. This
includes the bakelite and brass finger contact units of the steppers. We
gently sand them with 600 grit paper, wipe with alcohol and finish with a
small amount of lube gel. Also, the mechanical moving points of the stepper
as well is cleaned with alcohol and finished with lube gel.

Signed, new interested reader

Thanks Gary, I also recommend the use of Dow Corning "Electrical Grease #4" for
protecting connectors from corrosion as well as reducing contact resistance and thus heat.
Setting up EM/SS Drop Target banks
The correct way to setup a Gottlieb drop target bank is to
(after repairing any broken/missing targets/parts) press the plunger
of the lift arm all the way to the bottom of the, being careful NOT to
press on the lift bar itself. You are pretending to be the coil you
see, and thus only the plunger is pressed in. Now with the plunger
bottomed out in the coil, loosen the coil bolts (four of them) enough
that you can slide the coil up/down the slots, and slide the coil to
the point where all the targets have raised enough to JUST pass the
catch bar by about 1/32nd of an inch (1mm). Now tighten the four
screws, and double check the adjustment by dropping the targets and
pressing the plunger home.

This adjustment, if done properly, will reset the targets every time,
yet not break off the small stop tab at the very bottom of the
targets. If those are broken off, the targets are being lifted too
much. Pictures to come...

Gottlieb's Player Unit - Friend or Foe? (under construction...)

Player Unit  

Not for the first time have we worked on the Player Unit.
A great design by Gottlieb, it simplifies substantially the workings of a 4 player game.
One of the main problems with this unit has to do with adjustments.
Our first picture shows the PU in the Game Over - Fourth Player - 5th Ball. 

Ball 1 position
Here we have the PU after a RESET - the wiper disc is now set to Player 1 - 1st Ball.

Close up view
Backside of the unit for Ball one...

Player 1 Cam
Here we have the 1st player cam lifting the 1st Player switch stack

Player 3 Cam
Note 3rd cam has raised the 3rd player switchs

Player 4 Can - Off
4th Player switch stack: contacts open - off cam

Player 4 Cam - On
4th Player switch stack: contacts closed (on top of cam)

Plunger Stop Adjust
Here is the system relaxed.

Plunger Stop Adjust
Here is the plunger bottomed in the coil - note the stop bracket just above the arm.

Plunger Stop Adjust
Take a close look at how the linkages fit - this is with the plunger bottomed in the coil

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