Gold Wings (Gottlieb, 1986)

Posted on November 8, 2021 by Randy

Symptom: Blows fuse
Location: Parker, CO

Sometimes things are not what they seem. There are many fuses inside a typical pinball machine. Generally the more modern machines have more fuses. When a fuse blows, the assumption is there is an overload condition downstream that needs repair.

Usually when a fuse blows, it burns in the middle of the glass tube. This fuse was odd because it kept blowing on the end. The current measured about 4.8 amps and the fuse was rated at 6 amps, so it shouldn’t have been blowing. It turned out that the fuse holder had some corrosion on the clips, which was causing the connection between the fuse and the fuse clips to heat up. It got so hot, it melted the solder inside the end cap of the fuse.

The fuse holder was replaced and the issue was resolved.

Haunted House Pinball Machine (Gottlieb, 1982)

Posted on November 21, 2015 by Randy

Symptoms: Upper playfield pop bumper not working, lower playfield up kicker not working, playfield GI lights off, sticky flipper on lower playfield.
Location: Golden, CO

Sometimes when approaching a Gottlieb Systems 80 pinball machine, especially the Haunted House and Black Hole, which utilize different playfield levels, it’s easy to get overwhelmed. It’s good to stay focused on one problem at a time.

For the first issue, the pop bumper on the upper playfield had a broken wire. Re-soldered the wire to the coil, and we checked that off the list.

The next issue was the playfield lights not working. I found that the GI lighting fuse was blown. I replaced it, which solved the problem temporarily. I discovered later, while solving problems with the lower playfield, that the fuse blew again. The “U” relay controls the power to the lights and the solenoids on the lower playfield. When the machine senses the ball dropping down to the lower playfield, the “U” relay is activated. It turned out, the lighting fuse would blow whenever the “U” relay activated. That meant there was short in the lighting circuit on the lower playfield.

I’ve seen shorted lamp sockets on these machines in the past, where the center conductor pin shorts against the can of the socket. I checked each GI light socket and found one that was shorted on the left side. I bent the pins so they wouldn’t short, replaced the fuse and manually actuated the “U” relay, and the lights lit and the fuse didn’t blow again.

The problem with the lower playfield up-kicker was traced back to the big edge connector on the bottom of the Driver Board. The ground for that circuit was not making a good connection. I removed the old pin from the connector and replaced it with a new one.

When checking the operation of all of the controlled lamps, there was one lamp not coming on at all. I replaced the bulb, but that didn’t help. I traced the problem back to the Driver Board. It appeared the transistor was blown. I replaced the transistor and it still didn’t work. It turned out that once again, this was a faulty connection at the card edge connector, except this time the pin was shorting across the row to another pin deep inside the connector, thus grounding out the circuit. This is what caused the original transistor to blow. I replaced the pin and the lamp started working again.

After replacing a few bad bulbs, the machine was working and playing well.

Circus Pinball Machine (Gottlieb, 1980)

Posted on July 21, 2014 by Randy

Location: Loveland, Colorado.
Symptoms: Displays not working, playfield lighting blows fuse.

I was really impressed by how immaculate this machine was. It looked like it had just been un-crated. It definitely had low miles on it. No doubt home-use only.

The interesting thing about the displays is that the credit/ball-in-play display was working, and the score displays were not working. They were dark/off. I spent a few minutes looking at the schematic, searching for what was in common with the score displays, and at the same time, not in common with the credit/ball-in-play display. There was only one thing: the filament voltages for the display tubes.

The score displays run off a 5 VAC filament supply and the credit display uses a 3 VAC filament supply. So I started by measuring the filament voltage at the Player 1 display and sure enough, zero volts. I lifted up the playfield and found the 5 VAC leaving the power transformer. So somewhere in between a connection wasn’t being made.

I found the problem at a wire to wire backbox connector. In this case, there was a pin that wasn’t crimped correctly at the factory.

Crimp pin was installed incorrectly at the factory. The wire was inserted too far and the crimp went around the insulation rather than the conductor.

If I held the wire a certain way, the displays lit up. I replaced the pin with a new one and all was good.

The next issue was that the general illumination lighting on the playfield would randomly blow a fuse. This is usually caused by a short at one of the sockets. I checked each socket and found one that had been damaged (right near where the prop bar is used to prop up the playfield). Just the slightest vibration would cause it to short out. I replaced that socket and one other socket that was marginal.

Quick Draw Pinball Machine, Gottlieb 1975

Posted on May 5, 2014 by Randy

Location: Fort Collins, Colorado.
Symptoms: Score reels sticking, not resetting, 50 and 500 points items not scoring, not always advancing to next player or ball, bonus countdown issues, score accumulating when switching players.

The machine has been missing the rear door for the backbox for a long time and a lot of dust had settled in there. The switch contacts on the player unit needed cleaning and adjusting. This accomplished a lot in eliminating problems. The score advancing when changing players was due to the reset contacts (switch stacks P3 and P4) vibrating or set too close.

The player unit keeps track of ball numbers, player turns, and controls the reset of the scores. What makes working on the player units difficult is that the switch stacks are very close together. I’ve made a home-made switch adjusting tool that is able to fit in between switch stacks. I’ve also made some cleaning strips with a jogged shape them to help with switch cleaning.

Some of the decagon units needed to be rebuilt and contacts cleaned. A majority of the time was spent in the backbox. The owner will craft a new back door to help keep the dust out.

There were a few other mis-adjusted contacts on the bonus unit and the 50 and 500 point relays.

Another EM pinball machine saved.

Close Encounters of the Third Kind Pinball Machine (EM version), Gottlieb (1978)

Posted on May 5, 2014 by Randy

Location: Parker, Colorado.
Symptoms: Machine not resetting, points not registering, drop targets not resetting, bad light socket, and various other problems.

This is the rarer electro-mechanical version of this pinball machine.

On most EM machines, you can disconnect the credit subtract coil to put the game in Free Play mode. However, on this machine, there are switch contacts on the credit subtract lever that trigger the Start Relay (S). I bypassed those with a wire.

Next, the relay coil spring on the Reset Relay (AX) had been previously replaced with the wrong one that was much weaker. I traded the spring from the Hold Relay, where the spring tension is less critical, to the Reset Relay and then re-adjusted the contacts. This fixed the problem with the machine not resetting correctly.

Next, many of the point scoring relays such as the 500 point and 5000 point were not holding though a cycle of the score motor. They are all common and routed through the normally closed Motor 2B switch. This switch was simply out of adjustment.

Eight relays are routed through a common hold switch on the score motor.

One of the formed switch blades had broken off the score motor and a replacement was obtained from The Pinball Resource.

Broken formed switch blade from Score motor.

Some of the contacts on the player unit needed to be cleaned and adjusted, which is a typical problem with Gottlieb multi-player machines. The bonus stepper unit was gummed up and not advancing or awarding bonus. It was cleaned and rebuilt.

The spinner switch needed adjusting because it was scoring points with just vibration from the playfield.

After replacing a broken light socket and spraying the back side of the backglass with Krylon Triple Thick Clear Glaze (to help stabilize the paint and keep it from peeling), the machine was looking and working great!

Black Hole, Gottlieb Pinball Machine (1981)

Posted on April 4, 2014 by Randy

Location: Littleton, Colorado.
Symptoms: Overall tune up, spinning disk in backbox not working.

I didn’t get many photos of this machine. The owner was expecting a house showing and I was trying to get everything finished before the realtor came.

The machine needed a lot of little things fixed, everything from loose ball guides, rubber pieces, bad bulbs, broken bumper caps, broken bumper body, and drop targets. The machine had too many balls installed in it which caused problems with the outhole and the eject mechanism to the shooter lane. This era of Gottlieb machines can only hold 3 balls in the trough.

Lower playfield after cleaning and replacing broken pop bumper.

This machine needed a new motor for the spinning disk behind the backglass. The parts needed to replace these motors are (as of 4-4-2014):

Quantity	Description	Supplier
1	3 RPM Gear Motor, part no. 638158	Servo City
1	0.770” Set Screw Hub for 6 mm shaft, part no. 545576	Servo City
1	0.770” to 0.625” hub adapter, part no. 545456	Servo City
4	Socket Head Cap Screw 6-32 x 1/4”	Servo City or hardware store
1	Machine Screw M3 x 6 mm	Servo City or hardware store
1	#4 lock washer, split or internal star	Servo City or hardware store

The hub mounts to the motor, the hub adapter mounts to the hub with the socket head cap screws, and the motor mounts to the machine with the M3 screw. The screw holes in the front of the motor don’t align with the existing bracket, so I only used a single screw with a lock washer to mount the motor. It seemed sturdy enough.

The existing black flat-head screws that hold the disk to the old gear motor are reused to mount the disk to the hub adapter.

I attached a connector to the new motor and plugged it into the existing connector on the wire harness. I connected the polarity to spin counter-clockwise. Everything worked great!

I was recently at the Texas Pinball Festival and saw two Black Hole pinball machines and neither had working motors. It seems to be a common problem.

Underside of main playfield

Gottlieb System 80B Pinball Machines, Voltage Adjustment

Posted on March 16, 2014 by Randy

Tip: When adjusting the 5 volt supply on a Gottlieb Systems 80B pinball machine, adjust it to 5.00 volts or lower, but not below 4.85 volts.

The reason for this is the poor design of the Memory Protect circuit, located on the CPU board. There is a 3V zener diode (VR1) located on the CPU board that will start getting hot and fail if the supply voltage goes above 5.0 volts.

Zener diode with a bulge and crack along right side.

Zener diode (VR1) with a bulge and crack along right side.

Although the failed zener diode shown above was still basically working, I suspect it was acting intermittently, causing the CPU board to freeze up. Regardless, a bulging and cracked diode shouldn’t be trusted. This was from a machine where the 5 volt supply was adjusted over 5.00 volts (5.12 volts).

Also, the 5 volt adjustment pot on the power supply should be replaced with a fixed resistor. The pot will get dirty and become sensitive to vibration, causing voltage fluctuations. The best thing to do is adjust it for 5 volts, de-solder the pot from the circuit board, measure the resistance, and replace it with a fixed resistor or a combination of fixed resistors to obtain an equivalent resistance.

Tee’d Off Pinball Machine (Gottlieb, 1993)

Posted on October 28, 2013 by Randy

Location: Cheyenne, WY
Symptoms: Flipper problem, Spinner problem

It seems like every Gottlieb – Premier pinball machine I work on has over-fused flippers. The fuse should be 2.5 amps and in this machine there were 5 amp fuses installed. When the flipper link broke, it caused the flipper arm to not engage the End-Of-Stroke switch, which caused the coil to melt. Had the correct fuse been installed, the coil would have been saved.

I replaced the coil, the fuse and the broken link and everything is fine with the flipper.

The other problem, and I’ve seen this on a Monte Carlo pinball machine (which is the same vintage) is that the switches on the center spinner don’t work. In this case, the spinner wasn’t spinning very fast either. I cleaned and oiled the wiper contacts and the gears. I checked every hole in the spinner and verified that each switch was working.

The Games Pinball Machine (Gottlieb, 1984)

Posted on April 21, 2013 by Randy

Location: Brighton, CO
Symptoms: Pop bumper not working, display digit not working, needed cleaning and tuneup.

The machine was good condition. I should have taken photos because the photos in the IPDB are of a machine in very poor condition.

The non-working pop bumper was simply a broken wire going to the coil. I resoldered it. I checked the other pop bumper switches and noticed the top bumper’s switch was sticking. If you press down on a bumper skirt and it doesn’t immediately pop back, you’re asking for a burned-out coil. I cleaned the spoon that the bumper skirt rests on and that seemed to help a lot. Often the pointed end of the bumper skirt that contacts the spoon gets roughed up and needs to be sanded or filed smooth and round again. It’s a pain to do because it’s difficult to get to, and often involves removing it which requires taking the whole assembly apart.

The display on Player 3, least significant digit, was dead. I checked the card edge connector and made sure the card edge was clean. I fired-up the oscilloscope and saw that the pulses (4 volt) were going into the digit driver IC, but no 60V pulses were coming out of the pin for that digit. The other digit drivers within the IC were working fine.

The IC is a UDN6118A, which is no longer made. These can the purchased used on E-bay from Chinese distributors. There was also a new one available at a US chip broker, for $15, plus $8.99 shipping. Does it really cost $8.99 to ship something that weighs as much as a paper clip? No! For the same price, I can get 5-10 used chips from China.

For the time being, I swapped the Player 3 and Player 4 displays because the owner said the Player 4 gets used less often. The owner is contemplating whether to repair the display or live with it. I was surprised to see that PinScore doesn’t make aftermarket displays for Gottlieb (and neither does anyone else that I could find).

I also advised the owner that the rechargeable battery on the System 80A control board should be replaced before it leaks and ruins the circuit board.

I replaced bulbs and did a quick cleaning of the playfield.

When I played the game, I thought the sound board had something wrong with it. There was a lot of background noise. But it turns out the background noise is supposed to be crowd noise like at a stadium. I verified by watching a YouTube video of the same machine. You have to use your imagination. I think it would have been better to have some background music with an Olympic theme.

Haunted House (Gottlieb pinball machine, 1982)

Posted on March 10, 2013 by Randy

Location: Wellington, Colorado.
Symptoms: Would blow fuse as soon as ball landed on lower playfield.

The problem was obviously a short related to something that powered the lower playfield. I inspected the wiring and coils on the lower playfield and didn’t see any issues. With the machine off, I checked for shorts in coil and flipper power wiring and didn’t see any. I finally found the short with my meter in the playfield illumination wiring, and it turned out to be on the main playfield.

On the underside of the main playfield, there are 8 lamps that light the lower playfield. These lights only illuminate when the ball is on the lower playfield, and are controlled by a relay. Next I did a visual inspection of each of the 8 lamps, and as usual, found the short on the last one I checked. 😉 The center contact was shorted against the side of the socket, which is typically where lamp circuits short out.

The owner had replaced all of the lamps with LEDs. One important thing to note: On Haunted House and Black Hole, these 8 illumination lamps are powered by 28 volts, which will blow out regular 6 volt LEDs. The original bulb number is a #313. You either have to use an LED specified to replace a #313 bulb, or you have to modify the lighting circuit to operate on 6 volts (a procedure is here).

Peak Pinball

Pinball Repair in Colorado, serving Denver to Fort Collins

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