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Servicing the Gottlieb System 1 pinball games: 1977 - 1982

Cleopatra, Sinbad, Joker Poker, Dragon, Solar Ride, Count Down, Close Encounters, Charlie's Angels, Pinball Pool, totem, Incredible Hulk, Genie, Buck Rogers, Torch, Roller Disco and Asteroid Annie. Dead MPU? Try the Ni-Wumpf!

1) Recommended modifications to make the game more reliable:

2) Fix that driver board! Many Gottlieb driver boards did not have diodes - resulting in damage to MPU if a transistor fails...

3) Basic ground upgrades

4) Test procedures when you get the displays coming on...but there are problems...

5) Handy service tips...

6) Pop bumper meltdown

7) Game appears to be dead...cuts out at random, or won't start (you need a voltmeter here)

For more tips and tricks see also Gott System 1 page (the merge is not done yet....)

Gottlieb System 1

Cures for Gottlieb System 1 design faults.

There are four major problems with System 1 architecture. 

1) The destruction of the switch in/out control IC's by over voltage on the switch matrix

A cure that we are testing is to prevent the over voltage getting to the irreplaceable IC U5 - A1752CF after either the switch drives or returns are hit with either a static electric shock or the 24VDC solenoid bus. The protection is simple, there needs to be clamping diodes inserted in the circuit. These can be placed across the resistors R65 - R72 with the band of the diode (1N4002 or higher) soldered to the +5VDC end of the resistor and the non-band end to the other side of the resistor. Then on Resistors R57 - R62, connect the non-banded end of the diodes (1N4002..) to the junction of the resistor and the trace leading to the IC and the banded end to a convenient +5VDC bus tie point. 

The idea is that there are a pair of 1N4005 diodes on each input/output line, and the diodes are in series like this

(-12VDC)---|>|---(input/output)---|>|---(+5VDC) .

The (-12VDC) is the negative bus rail, and the (+5VDC) is the +5 bus rail. The ---|>|--- is a diode. The (input/output) is EITHER the input or output line to be protected. This will prevent the input/output lines from going above the +5VDC line and thus protect the IC's from the 24VDC solenoid bus or the 6.3VAC light bus power.

I hope that is a bit clearer. For a rough picture see photo.. I will update this picture in the near future, it is not very good...

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2) System 1 lamp/solenoid driver board design problems
		The earlier run of Gottlieb driver boards did not isolate the MPU board from the solenoid driver transistors, and if a coil shorted out, this can cause serious damage to the MPU board. Essentially making it very expensive to service! Please check the picture on the lower left (here is a circuit diagram with the diodes) and see if you have these on your board. The early boards can be updated by inserting diodes directly at the base of the driver transistors (picture #2), or traces were cut on the back and the diodes soldered in (picture #3). The recommended diodes would be 1N4002 to 1N4005 series, Do not use a 1N4001, at 50V it is not rated with a high enough breakdown voltage. We recommend that ALL Gottlieb System 1 game owners confirm this modification has been done, as even though the factory did this modification after the third or fourth pinball in that series, there is always the chance that you do NOT have a modified driver board due to a substitute repaired driver board some time in the past!
Early System 1 Driver Board  -NO Diodes-
Later Revision Driver  Board  with added  Diodes
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3) The ground connection on the power supply...(for more depth go here)
Power Supply With   Added  Ground Wire		Please note that ALL Gottlieb Electronic pinballs have problems with the ground connections. This stems from their refusal to learn from Williams, Bally and Stern's use of the metal shield as a ground plane for the game boards. Gottlieb System One pins had only a single ground pin going to the regulator supply, and this would weaken over time the same way as the System 80(X) problems are covered below. A simple cure for the System 1 and 80(X) regulator supply ground problems is to connect the ground plane of the regulator circuit board to one or two of the studs that the securing screws use to hold the circuit board to the regulator's heat sink, and then making sure that the heat sink frame is connected to the cabinet ground plane. All you need to do is add a wire from the (-) end of the large filter cap to the bolt on the underside of the frame - see the photo. If you have to take the supply apart for repairs then here is a picture of the mod done to a System 1 power supply (the BLACK wire), also note the fresh heat sink compound (silicon) on the both the outboard +60VDC regulator transistor and the -12VDC regulator.

4) Slam switch issues:

Typically you will turn the game on and the displays will come on IMMEDIATELY. No 5 second delay, no "Click-Click". You might well see the displays showing a wave like this O0O0O0 then 0O0O0O right to left flowing...we recommend that you disable the troublesome/useless SLAM circuit at the MPU board by shorting to ground the junction of R12 and C2.

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5) "Handy Service Tips for System 1 games 

The following conditions represent unusual problems which have occurred and which, for the most
 part, according to Gottlieb's service engineers, are easily prevented or solved.

Symptom: Game goes to "GAME OVER" during play for no apparent reason.

Solution: a) Check the two normally closed SLAM switches for adequate pressure.
              Improperly adjusted switches will respond to game vibration levels and
              produce this symptom.

          b) Check the suppression diodes across the pop bumper(s), flipper and kicker
              coil(s). An open diode or a broken solder connection can generate this
              symptom (true for most brands of pinball games - jrr).


Symptom: While resetting the score levels stored in memory, holding the credit button in
            fails to increment the score setting>

Solution: This problem and others which may occur while adjusting score levels can be
            prevented by insuring that all drop targets are reset before attempting to
            adjust the score levels.


Symptom: Game will register only one credit when coins are deposited and the book-
            keeping memory appears to be blanked.

Solution: Power supply capacitor C2 (220pf) limits high frequency noise on the +5VDC
            supply. If this capacitor opens, the bookkeeping functions will be inhibited.  

Finally, please move the battery away from the MPU board. We recommend that you use two extension wires (red and black if possible) and have the battery lying on the bottom of the headboard (in a plastic bag) to protect against battery corrosion. For more info see our battery corrosion page.

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6) Subject: Re: TECH: Pop Bumper Coil MELTDOWN!!!

To: All

And another response to that age-old question...
 
>The question is:  what happened?  Any ideas?  Is 
>there something else I ought 
>to be checking so this doesn't happen again?  BTW: 
>The pop bumper coils are 
>"non-controlled" solenoids, so the MPU/Driver boards don't control the 
>activation of the coil, just the "cup" switch on the bumper itself.

 JND> Those non-controlled coils in the older games are the worst thing ever
 JND> invented ... I had a Time Machine *burn* after it's 
 JND> non-controlled section
 JND> on the CPU melted and then burned ... left a hole the 
 JND> size of a quarter in

Well, actually on this vintage of game Gottlieb had a direct control pop 
bumper. The cup switch had tungsten points and fired the coil all by 
themselves. The argument went that the computer controlled coils would not
respond fast enough to the balls trying to tango between two tightly tuned
pop bumpers, so let's have them bypass the cpu completely. Same idea occurred
to Williams but they, as you mentioned, made a boo-boo by allowing the cpu
to control the coils (who need that any ways??), which led to holes appear-
ing in their solenoid driver boards when idiots over fused them.
If the pop bumper (back to the original question) cooks then you must check
the condition of the contacts, you will probably find that they are pitted
and this causes the contacts to momentarily 'weld together long enough
to blow the coil. Replace the contacts when you replace the coil (get tungsten
contacts) and set them so when you push on the bumper skirt on any point
that the actuator pops back the middle with assurance. A little white
lithium grease is sometimes in order in the cup.
:-#)#

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7) "Game won't start? Works for a minute or two, then stops? Dies when the flippers are flapped? Then you might have a power supply problem. The simplest test is to check your main filter capacitor on the power supply. Check across the large capacitor on the power supply, there must be at least 8VDC across it (note if you get over 50VDC, then you are checking the wrong capacitor-that is the display filter cap.), and on the AC setting of your voltmeter, less than 0.75VAC across it.
	Check for 5VDC across the upper capacitor, and if good, then wiggle the connector and make sure the voltage doesn't vary. If it does, then polish the edge connector on the underside of the MPU board with an INK eraser. Then plug/unplug the connector a couple of times to clean its' contacts.		Check for 12VDC across the lower capacitor and repeat the same steps as  for the +5VDC
	If the 5VDC seems low, then check across the main filter capacitor on the Power Regulator board. It should be at least 10VDC or better, on our game here it is 13.89		At the same time you should also check the AC reading across the primary filter capacitor. It should be less than 0.75VAC. Ours here is 0.69VAC, a little high, but on the other hand the DC volts are very good and this cap then passes. One last point, if the capacitor is hot to the touch after 15 minutes on, then it is failing and must be replaced.