It seems like when the P relay is energized, it's not keeping the score motor running...

After the first ball goes into the outhole and then kicks over to the shooter lane to start ball 2, take a look at score motor switch 2B - maroon/green wire and slate wire. Is score motor switch 2B closed? If yes, go to the P relay and manually close the switch with the blue/white wire and the maroon/green wire. Use a non-metal probe/stick to close just that one switch. When you close that switch does the coil lock on and remain energized?

Also, do the same test on the P relay switch with yellow/red wire and red/white wire. Manually close the switch. When you close that switch, does the score motor start to run?

After the 1st ball is played and the ball kicks over to the shooter lane, ball 2 ready to shoot, and with score motor switch 2B closed, try the following tests:

Manually push in the P relay where all of the switches close/open/move at the same time. Quickly push in the relay and release. Does the P relay lock on and stay energized?

Connect one end of the jumper wire to score motor switch 2B - slate wire. Touch the other end of the jumper wire to the blue/white wire of the P relay coil. Does the P relay coil stay energized when the jumper wire is placed on the P relay coil wire lug?

Connect one end of the jumper wire to score motor switch 2B - maroon/green wire. Touch the other end of the jumper wire to the blue/white wire of the P relay coil. Does the P relay coil stay energized when the jumper wire is placed on the P relay coil wire lug?

Test with machine powered off:

Do you have a 9 volt battery? If so, power off the machine and place the 9 volt battery terminals on the wire lugs of the P relay coil. Does the coil stay energized when the battery is connected to the coil?

Wanted to confirm on this question:

"Manually push in the P relay where all of the switches close/open/move at the same time (score motor switch 2B closed). Quickly push in the relay and release. Does the P relay lock on and stay energized?"

You said, No?

The test where you connected the jumper wire to score motor 2B - slate wire - has constant power with only anti-cheat switches between switch 2B and the transformer. So, the other end of the jumper wire would be a "live" wire with constant power and touching it to a positive coil lug would energize and lock on the coil keeping it energized.

Could the P relay coil be shorting out or have some type of issue???

Do you have a multimeter? You could test the resistance of the coil. Resistance on the A-9735 would be around 15 ohms. I would test the resistance of the coil with the wires connected and then again with wires disconnected. Do you have a basic soldering set?

The A-9738 coil is a hold relay coil and has a higher resistance of around 30 ohms. It might work as temporary testing coil...

I would do the test with the jumper wire one more time. One end of the jumper wire to score motor switch 2B - slate wire, and place the other end of the jumper wire to the P relay coil with the blue/white wire. The coil should be constantly energized when you place the wire on the P relay wire lug. If the coil energizes and then de-energizes, on and off for different lengths of time, then check the anti-cheat switches.

Anti-cheat switch - slate wire and red/white wire
Bounce switch - red/green wire and red/white wire

Make sure these switches are thoroughly clean and tightly closed.

Along the way, any relays and switches you are checking, make sure the switch stack screws are tight.

Do the same test with the jumper wire again, but this time block the P relay switch - blue/white wire and maroon/green wire with a thick piece of paper, business card, etc. Place the other end of the jumper wire on the P relay coil wire lug and see if the coil will energize, lock on and stay energized.

If there's still intermittent power to the P relay coil when using the jumper wire, then you can replace the coil and use the A-9738 coil for testing...

It looks like from the video the P relay coil does constantly energize when using the jumper wire from the 2B switch...

Researching this, another issue may be with the coin unit. If the alignment of the coin unit wipers is off, this can prevent the game ball from advancing. Manually operate the coin unit by advancing and resetting it. Check the wipers on the coin unit to see if they are aligned properly with the contact rivets. Check the leaf switches on the coin unit to see if they open and close properly.

I'm not giving up yet... I'll research more this evening and post more info tonight... Thanks...

We'll need to take a look again at the circuit that contains the P relay. This circuit shares switches with the primary start circuit. It seems the machine initially resets properly. To confirm, when you press the start button once, the machine resets, score reels reset (some need manual reset), the ball kicks to the shooter lane, and the backglass lamps show a 1 player game on ball 1.

After the machine resets and after the 1st ball enters the outhole, the machine uses another circuit to process the changing of the players and the ball in play count. From the operating instructions:

"The remaining balls that enter the outhole (starting with the game play end of ball 1) are kicked across the trough switch (through switch) which pulls in P relay. P relay runs the score motor. Switches on U relay, score motor 2C, P relay, BX relay and score motor 1A advances the player unit the required number of steps determined by the player unit switches and the coin unit."

So, we should start to closely examine these switches in the circuit:

Score motor 1A switch - blue/white/red wire and white/slate wire - normally open switch
This switch is also used by the main starting circuit; confirm it is clean and adjusted properly; with machine powered off, manually rotate the score motor to see if the switch opens and closes correctly

BX relay switch - white/slate wire and yellow wire - normally closed switch
Last ball switch; confirm the switch is clean and closed

P relay switch - yellow wire and yellow/blue wire - normally open switch
Player relay switch; confirm switch is clean and adjusted properly;

Score motor 2C switch - yellow/blue wire and white/blue wire - normally open switch
Confirm switch is clean and adjusted properly; with machine powered off, manually rotate the score motor to see if the switch opens and closes correctly

U relay switch - white/blue wire and slate/yellow wire - normally open switch
1st ball switch; confirm switch is clean and adjusted properly; switch needs to close when score motor is running

I relay switch - slate/yellow wire and red/white wire - normally closed
Extra ball switch; main gateway switch that supplies power to the circuit; only opens when extra ball is activated; confirm switch is clean and adjusted properly

Then check the following:

I relay switch - Is there 25 volt power at the switch lug with the slate/yellow wire? Check the voltage at the switch with a multimeter.

U relay switch - Is the switch closing before or during the ball advance to send power to the next switch? After the 1st ball ends and the 2nd ball is kicked to the shooter lane, a jumper wire could be used on the switch to bypass the switch; jumper at the white/blue wire and the slate/yellow wire; manually close the switch to see if there is power on both sides of the switch using a multimeter.

Score motor switch 2C - Is the switch closing during the change between game balls?

P relay switch - Is the switch closing and receiving power from switch 2C?

BX relay switch - Is the switch closed when the score motor is running and during the change between game balls?

Score motor 1A - Is the switch closing during the change between game balls?

You'll want to test if power is getting to the circuit starting at the I relay switch with the slate/yellow wire. Set your multimeter to AC voltage (V~) and choose the 200 volt AC setting. Place the red lead on the slate/yellow wire lug and the black lead on a machine ground - the black wire at the transformer or a black wire at a coil. The multimeter should read approximately 25 AC volts. Then place the red lead on the U relay switch with the slate/yellow wire. Check for 25 volts. With the switch closed, put the red lead on the U relay switch with the white/blue wire. You can check any of the switches using this method if you close the switch in question. From your description, you should see power up to score motor switch 2C with the blue/white wire, since 2C is a normally open switch.

In order for the player unit solenoid (coil) to be energized after the 1st ball enters the outhole, the following switches need to be closed all at the same time:

I switch - U switch - 2C switch - P switch - BX switch - 1A switch

The issue is that the process happens using 1/10ths of a second, so it's difficult to see all the switches closing at the correct time. So, it's all a timing situation when relay switches and switches on the score motor all close at one point in time.

When the 1st ball enters the outhole, it will be kicked over the trough switch (through switch), which will energized the P relay coil. A switch on the P relay will make the score motor run, in turn, will make the score motor switches 1A and 2C close. If there is power at the 2C switch, when it closes, it will send power through the P relay switch, BX relay switch and the 1A score motor switch. So, you would want to check if score motor 2C switch is "armed" with power before the trough switch is closed.

You noted that BX relay switch with the yellow wire and white/slate wire was open when the score motor was running between ball 1 and ball 2. This BX switch needs to be closed during the end of ball 1 and the start of ball 2. If the switch is open during this process, then the switch will need to be closed in someway for testing purposes. You could adjust the switch so it's always closed, disable the BX relay by blocking an O relay switch, so it won't open the BX switch, or temporarily disconnect the power wire from the BX relay coil. BX relay coil is part of an "inter-lock" relay (BX coil and BXR coil). So, try to get that BX switch closed and then see what happens when ball 1 enters the outhole and kicks over to the shooter lane to begin ball 2.

If you're just closing the one BX switch - white/slate wire and yellow wire - it should not end the game. It might be related to a jumper wire on the relay.

When that BX relay switch is closed, and after ball 1 enters the outhole, and the trough switch is closed , does it energize the player unit coil?

Power off the machine and then power on the machine. Reset the machine so ball 1 kicks to the shooter lane to begin the game. Then power off the machine. Look at the BX relay switch with the white/slate wire and yellow wire. Is that switch open or closed?

Also, take a look at the 3-5 ball adjustment plug. Is the plug inserted in the 3 ball game or 5 ball game receptacle? Is the plug fully seated? Check all the wire connections on the plug assembly.

Check the voltage of the machine right from the transformer. Using your multimeter, place the red lead on the transformer lug with the red wire, and the black lead on the lug with the black wire. Read the voltage. Then place the red lead on the fuse block - first on the wire lug with the red wire, and then on the wire lug with the red/green wire. What voltage readings do you get?

You can continue checking the voltage up the circuit. Check the voltage on the following:

With Bounce Switch Closed:
Bounce switch - red/green wire
Bounce switch - red/white wire
With I Switch Closed:
I switch - red/white wire
I switch - slate/yellow wire

I'm not sure what you meant about the movement of the player unit:

The player unit only rotates in one direction and it is "powered" by one coil (solenoid). The coil needs to be energized in order for the player unit disc to rotate.

The BX and BXR latch relay(s) hold the switches in two different positions. A normally closed switch will be closed when the BX relay is in its resting position. When the BX coil is briefly energized, it will move the latch to a second position and the normally closed switch will then open and be held in the open position without the help of the BX coil. When the BXR coil is energized it will return the latch to the 1st position returning the switch to the closed position.

The BX relay is the last ball relay. The BX relay coil receives power from the player unit. Take a look at the player unit and manually rotate it by pushing the solenoid plunger. Does it rotate smoothly and click into each position? Check the wipers and contact rivets. The player unit can swing downward so you can see the five switch stacks operating. Inspect the switch stacks and switches. Check if the Allen screws on the hub of the disc are tight.

If your multimeter readings are correct, there are some issues with the power delivery to the I relay switch. Looking at the schematic, there are no switches between the bounce switch and the I relay switch. So, if you're reading 29.55 volts at the output of the bounce switch, there should be a reading of around 29 volts at the input of the I relay switch. I'm guessing 4.26 volts would not be enough voltage to fully energize a stepper unit solenoid. Is there damage to the red/white wire in that part of the circuit???

You can use a jumper wire to get the 29 volt power to the I relay switch. Connect one end of the jumper wire to the bounce switch with the red/white wire and connect the other end of the jumper wire to the I relay switch with the red/white wire. Then, with the jumper wire connected, take two voltage readings at the I relay switch:

With I Switch Closed:
I switch - red/white wire
I switch - slate/yellow wire

At both sides of the I relay switch, you "should" get a voltage reading of approximately 29 volts, or you'll get something like 35 volts, which would mean there is "bleeding" voltage present in the circuit.

You should also check if you're getting low voltage in any other branch circuits. Check the voltage on the AX relay switches with the red/white wires. What are the voltage readings at these AX relay switches?

With the jumper wire installed, the voltages look near normal... I'm thinking there is a short in the circuit somewhere on the red/white wire.

With the jumper wire installed between the bounce switch and the I relay switch, power off the machine and then power it on. Reset the machine and start a game, and see what happens when the 1st ball enters the outhole.

That was definitely a strange issue. You usually don't see a short in a straight wire without switches. It will be interesting to find out where the short is located.

So, it looks like the switches were operating normally, but the circuit had very low voltage, which wasn't enough voltage to energize the player unit advance solenoid.

To get some clues, test the voltage at the AX relay switches with the jumper wire installed on the bounce switch/I relay switch, and test the AX relay switches again without the jumper wire installed. This might tell you if the short is in a main circuit or a branch circuit.

You should get approximately the same voltage at the AX relay switches compared to the voltage at the transformer. In this case, it would be around 29 volts. I'm wondering if the jumper wire at the I relay switch would affect the voltage at the AX relay switches. The schematic shows that a main circuit supplies power to the AX relay switches. There is a branch circuit that goes to the I relay switch before power reaches the AX relay switches.

Note: A couple of the switches on the AX relay handle 6 volt power for the lamps.

Yes, if the bounce switch and the I relay are located in different "areas" of the machine - ie bounce switch in main cabinet and I relay switch in the back box - then the wire between the two would need to go through a Jones plug. So, you're right in this example, the wire would break, but the Jones plug would permanently restore the connection.

On a side note, the wiring harness on your machine is bundled using zip ties near the U relay. Gottlieb did not use zip ties on this machine when it was made. Maybe there was an attempted wiring repair done previously on the machine.

I'd check the playfield Jones plug assembly to see if it might be shorting at the plug. Take a voltage reading on both sides of the Jones plug assembly... You can also unplug the playfield Jones plug and do a continuity test with a multimeter. Test the red/white wire between the bounce switch and the Jones plug. Then test the red/white wire between the Jones plug and the I relay switch. This should tell you what side of the Jones plug the short is on - in the main cabinet, on the underside of the playfield, or in the wiring harness running through the cabinet pedestal.

There are various branch circuits in the machine that use a red/white wire. These branch circuits are connected to the main circuit, which also uses a red/white wire.

You want to determine you're working with the correct red/white wire. Looking at the schematic, with the machine powered off, you should be able to do a continuity test on the red/white wire that goes from the I relay switch to the Jones plug in the backbox.

Gottlieb did use, on rare occasions, wires colors that were different than the wire colors listed on the schematic. But, it's still strange that the Jones plug has a red/white wire and connects with a green/orange wire. So, is this a short circuit issue, or is it a connection issue where the other part of the red/white wire is not connected to the Jones plug assembly??? At one point did someone install the green/orange wire on the Jones plug connector and wanted to connect the other end to a newly added F relay? Then a red/white wire would lead back from the F relay to a Jones plug? Maybe some type of wiring experiment at the factory???

You can test the circuit again by connecting a jumper wire to the green/orange wire on the Jones plug lug and the other end of the Jumper wire to the bounce switch with the red/white wire. Then start a game and see if it plays normally.

Yeah, I saw that writing on the schematic. Some other clues are that some of the wiring is arranged in an unusual way (not factory), the type of F relay used in the machine, and the internals of the machine look like new, as if it was never on a vending route and wasn't played that much. Like you said, could this be a pre-production machine? Where did you buy the machine? Did the previous owner have any information about the machine? Is the serial number on the machine still visible? You can check the IPSND for more information about serial numbers:

http://ipsnd.net/View.aspx?id=2293

You can also check for a stamped serial number in the front of the exterior cabinet above the coin door frame, and a printed serial number at the top exterior of the backbox.

If the machine plays normally with a jumper wire between the I relay and the bounce switch, then maybe there is one missing wire that was removed from the machine for testing purposes. I'm not sure if you can recreate the "stock" wiring, because some of the wiring in the machine (color type) is not matching up with the schematic. And we're still not sure about the F relay that is used in the machine.

An example: From the I relay, the red/white wire travels to the backbox where it connects to a backbox Jones plug. It would continue traveling in the backbox to feed branch circuits. The red/white wire would then need to exit the backbox via a Jones plug. The red/white wire would then travel through the main cabinet and then connect to the bounce switch.

You confirmed that the red/white wire from the I relay goes to the 8 plug Jones plug in the backbox. And you said the red/white wire from the bounce switch go to the 10 plug Jones plug in the backbox. Both of the red/white wires at the Jones plugs are a mismatch with the connecting wires - red/white to brown/white (10 plug), and red/white to green/orange (8 plug). Would the machine work normally if you put a jumper wire on the backbox Jones plugs between the green/orange wire on one Jones plug socket to the brown/white wire on the other Jones plug socket? In post #54, you showed a photo of the backbox where the green/orange wire and brown/white wire did not connect to anything. Are these wires just left over from an engineering experiment???

I'm glad to hear you found the problem!... The simplest things are the hardest to fix... I think those "rogue" wires in the backbox complicated our troubleshooting methods... I hope you'll eventually find the serial number on the machine. It would be interesting to see if the machine is a sample game... Enjoy playing the machine! FS...

Coils getting "too hot" is a common issue in Gottlieb machines. The U relay coil is a continuous duty relay coil and it will become weak and get hotter over time. First check if you have the correct coil in the U relay. Schematic shows a A-9740 coil. Other sources on the Web say it's an A-9736. Both will get hot. You can keep using the present coil, install a new coil, or modify the relay with a solid state coil, so it will run cooler.

Clay's Pin Repair Web site has a good section explaining continuous duty relays and how to modify the relay with a solid state coil:

"Modifying the Continuous Duty Relays for No Burn, as used in Ax/Bx Games"

http://www.pinrepair.com/em/index3.htm#reset