For the tilt issue, during normal operation when the machine is powered on, it will be in tilt mode with the playfield lights turned off...

What actually happens when you try to start a game? You push the credit/start button, the score motor starts, the score reels reset, and then everything stops and the machine goes back to tilt mode? When the game starts to reset, do the playfield lights turn on?

There are two tilt relays on this machine - a tilt relay and a tilt hold relay. The tilt relay is connected to the tilt switches. When one of the tilt switches close/open it will energize the tilt relay. This, in turn, will close a switch on the tilt relay and energize the tilt hold relay. T relay is the tilt relay and I think H relay is the tilt hold relay. Check the following:

T relay - manually operate the relay and make sure the switch contacts are clean and adjusted properly; after a game reset, is the relay energized?
H relay - after a game reset, is the H relay energized?
AX relay - make sure the switch contacts are clean and adjusted properly

P relay would be the add player unit relay... Looks like the H relay coil is not being energized. Make sure all the switch contacts are clean and adjusted properly on the T relay and AX relay...

The AX relay coil can get hot, but it shouldn't be burning hot. There might be a resistance issue with the coil - then the coil would need to be replaced. You can check the resistance of a coil with a multimeter.

https://www.flippers.com/coil-resistance.html

1. Game is not ending after 5 balls. It just keeps on going. - Check the player unit. Manually operate and rotate the player unit to make sure to rotates smoothly and "clicks" into each position.

2. The Ball in play lights aren't working nor are the Player 1-4 lights (I pressed the Start 4 times). - Check the Q relay. Make sure the switches are clean and adjusted properly.

3. The switches behind the rubbers as well as the switch in the shooter lane aren't registering. - Clean and re-seat the playfield Jones plugs that connect to the main board and the backbox.

4. When the ball goes into the kickout hole, the ball kicks out but the coil is firing 3 times after the ball is gone. - Check the adjustment of the contact switch under the kickout hole; check the G relay switches for the proper adjustment.

I'm working from a Royal Flush so the wiring should be very similar for non-playfield scoring circuitry.

1. Game is not ending after 5 balls. It just keeps on going. - Check the BX relay circuit. Check score motor switch 1C (brown/black wire) and O relay switch (brown/black wire).

2. The Ball in play lights aren't working nor are the Player 1-4 lights (I pressed the Start 4 times). - Two switches are used to send power to the ball in play lights and the 1-4 player lights, which are the AX relay switch and the Q relay switch. When the game is reset, AX switch with the black/red wire should be closed and Q switch with the orange/black wire should be closed.

4. When the ball goes into the kick out hole, the ball kicks out but the coil is firing 3 times after the ball is gone. - If the coil is firing 3 times, this means power is being sent to the coil from one of the score motor switches. The normally open switches for the hole kicker relay are G relay switch and score motor 4C switch. The normally closed switches are X relay switch and BX relay switch. Check all these circuit switches for possible issues.

I would recommend cleaning all of the Jones plugs and Jones plug connectors in the machine to make sure they are making a good electrical connection.

Manually pushing the start relay should get the score motor running. This score motor circuit will have a bounce switch, the start relay switch and possibly a service jack plug. Make sure the start relay switches are clean and adjusted properly, and check for a service jack plug near the score motor.

First, see if power is getting to the score motor. Power on the machine and then manually close the one switch on the start relay with the yellow/red wire and red/white wire. This will make the score motor run. If nothing happens, then it might be a problem with one of the three switches / connections in the circuit:

Bounce switch - red/green wire and red/white wire
S relay switch - yellow/red wire and red/white wire
Score motor service jack - yellow/red wire

Also, check the 15 amp fuse and fuse block in the circuit with the red wire and the red/green wire.

Power off the machine. Attach one end of a jumper wire to the 15 amp fuse block (red/green wire). Power on the machine. Touch the other end of the jumper wire to the score motor service jack input (on position). Score motor should start running.

Power off the machine. Then, with the jumper wire still attached to the 15 amp fuse block, manually close the switch on the S relay with yellow/red wire and red/white wire (temporarily adjust the switch to the closed position or clip the switch to the closed position). This will create a "closed" circuit for the score motor. Power on the machine. Check the other switches in the circuit with the other end of the jumper wire:

1st check - S relay switch - wire lug with yellow/red wire
2nd check - S relay switch - wire lug with red/white wire
3rd check - bounce switch - wire lug with red/white wire
4th check - bounce switch - wire lug with red/green wire

When you touch the jumper wire to one of theses switch lugs and the score motor does not run, then you'll know where the circuit connection problem is located.

At this point, when you used the jumper wire at the fuse block, you created a closed circuit without switches:

transformer > fuse block > service jack > score motor > transformer

With the jumper wire connected to the fuse block, I would confirm you have voltage at the following test points using a multimeter:

transformer - red wire
fuse block - red wire
fuse block - red/green wire
service jack input - input connector - yellow/red wire
service jack plug - blue wire?
score motor - positive wire lug

There also might be a ground issue. You can use a jumper wire on the negative score motor wire lug with the black wire and connect the other side of the jumper wire to the black wire at the transformer.

Is the score motor stuck? Try to manually rotate the score motor disc to see if it will turn and activate the score motor.

There should be a label on the transformer that shows the voltage of each transformer lug. You're looking for the 25 volt connection. You can also look for solder "witness marks'' on the wire and the wire lug to see if the solder break is similar. Or measure the voltage at the transformer lug with a multimeter - should be around 25 volts AC...

The switches that are closed are usually bounce switches that cut power to the machine when they open. The tilt switches are open and when a tilt switch is closed, it will send power to the tilt relay, which will put the machine in tilt mode. Your machine should have 2 or 3 tilt switches. Find the tilt relay on the schematic and then follow the circuit to the tilt relay switches and you'll see a group of tilt switches. When the machine is powered on, it will be in tilt mode - tilt lamp on in backglass, no playfield lights...

The schematic shows there are 3 tilt switches, which are normally open. Tilt switches will have an orange/white/red wire and a red/yellow wire. The first photo of the slam/bounce tilt switch looks like it's mis-adjusted.

What happens when you press the credit/reset button?

Power on the machine - backbox GI is on; tilt light is on; no lights on playfield
Press the credit/reset button - machine starts the reset process; score motor starts; score reels reset to zero, etc
Ball kicks to shooter lane
Then what happens???

When the machine goes into tilt mode, do the playfield lights turn off and the tilt light turns on? Or does the whole machine briefly power off and then turns on into tilt mode?

Power is getting to the tilt relay coil after the score motor stops. Referring to the photos in post #40, did you adjust the tilt switch with the orange/white/red wire and the red/yellow wire? This tilt switch needs to be in the normally open (NO) position.

Any of the three tilt switches with the orange/white wire (schematic: orange/white/red wire) are the switches that send power to the tilt relay. All of these switches are normally open.

Any of the other switches that can tilt the machine by interrupting power, these switches are normally closed switches.

If the machine starts to reset and tilts, then there would be an issue with one of the normally open tilt switches. Check the tilt plumb bob plate, the ball tilt switch and the playfield tilt switch. Look for shorting at the switch/plate - wires touching, wire lugs touching, etc. You can also disable each switch/plate one at a time by removing the orange/white wire from the switch stack or plumb bob plate.

Example: Power off the machine, and desolder the orange/white wire from the ball tilt switch. Then power on the machine and reset the machine. If the machine doesn't go into tilt mode, then there would be an issue with the ball tilt switch. If the machine does go into tilt mode, then you would need to do the same test with the other tilt switch / plumb bob plate by desoldering the orange/white wire one at a time.

A coil (solenoid) on a score reel that is constantly being energized on and off will get very hot. During normally game operation the 10 point score reel solenoid will get hot. But, the score reel solenoid should not be constantly energized or "stuck on." If the solenoid was actually "smoking," it has been damaged and it will need to be replaced.

Gottlieb machines in this era had grease applied to the score reel mechanism at the factory. Over time, this grease becomes gummy/sticky and creates havoc with the operation of the score reels. The correct way to solve this issue is to take apart the score reel unit, clean off all the old grease, sparingly apply new lubrication and then reassemble the score reel. It's time consuming when you have to do this on 16 score reel units, but well worth the effort.

The mini-stepper looks like it might be the F relay disc (00-90 unit) that is part of the number match feature.

I was trying to figure out where those loose wires would attach near the F relay. I don't have the full schematic for Spirit of 76 , so I was working off a Royal Flush schematic. The Royal Flush schematic shows the F relay has 2 normally open switches and 2 discs:

2A, 2 Disc 00-90 Unit Relay

Going back to HowardR 's post at post #55, the Spirit of 76 schematic shows the F relay has only 2 discs:

2 Disc 00-90 Unit Relay

Can you see any F relay switches on the Spirit of 76 schematic? On Royal Flush there is one 25 volt F switch at 8E on the schematic, and a 6 volt F switch at 3B on the schematic.

So, it seems like your F relay is matching up with the Royal Flush schematic, and I figured out where some of the wires attach. But, if the Spirit of 76 does not have a leaf switch on the F relay, then that makes this a bit confusing.

On the Royal Flush schematic, the F relay switches are part of the 6 volt/24 volt circuit for the playfield special kickout hole.

Does it look like the F relay had been replaced at some point? On the F relay, does the leaf switch have 2 normally open switches? Does it look like one of the wire lugs are missing from the switch stack on the F relay switches?

As rolf_martin_062 mentioned, different machines had different versions of the F relay. Could the F relay on your machine be a replacement and it was originally from a different machine?

I didn't see any F switches on the Spirit of 76 schematic. Looking at the photo of the F relay, maybe someone added the switch to the relay. The wire lugs on the switch stack look like they never been used - they look too clean. And one of the switch stack mounting screws is damaged, which tells us someone was maybe trying to install/remove the switch...

Referencing those two wires, are the same color wires attached to the male connector of the Jones plug? If so, can you trace the wires to the main cabinet to see where they go?

Yes, I don't see any F switches on the Spirit of 76 schematic. The photos of the backbox on IPDB are from a sample game / pre-production game and the F relay is located on a relay bracket bank on the side of the interior in the backbox. I guess they relocated the F relay near the credit unit on the production games. I'm still not sure what that switch is for - maybe a custom modification by a previous owner or operator.

The M relay is the 100 point relay. Most of the circuits that feed the M relay coil have multiple switches. A few of the circuits have one open switch. Can you post a photo of the section on the schematic that shows the M relay?

There's about ten different circuits that can send power to the M relay coil. I'd first look at the simple circuits to see if a switch is mis-adjusted. Check the following:

A relay switch - orange/black wire and yellow/blue/red wire
B relay switch - orange/black wire and blue/white wire (for a 5 ball game)
C relay switch - orange/black wire and yellow/blue/red wire

These are all normally open switches. Make sure they are clean and adjusted properly. If they check out okay, then try to recreate the issue again where the M relay coil is constantly energized. Then look at the above switches - are any of those switches closed when the M relay coil is energized?

1. I am not seeing ball in play lit up ---
The ball in play lights are controlled by the player unit. Does the player unit rotate when you start a game? Can you manually advance the player unit - does it rotate smoothly and "click" into each position?

4. Flippers super weak ---
A common problem causing a weak flipper is a mis-adjusted EOS switch and/or a worn out EOS switch contact. Check the EOS switches for adjustments and dirty/worn switch contacts.

For an incomplete reset process: Confirm the ball is fully seated in the outhole and that the outhole switch is clean and adjusted properly. Does the player unit rotate during the reset process?

Take a look at the operating instructions / start up sequence to see where the reset process stops:

https://pinside.com/pinball/forum/topic/gottlieb-spirit-of-76-#post-5831989

You'll need to find out "when" the reset process stops.

Check the 1st ball relay (U relay). When you press the credit/start button, does the 1st ball relay coil energize?

Then check the coin unit. When you press the credit/start button does the coin unit advance to the next position?

Test the coin unit by first manually advancing the coin unit to the 3rd or 4th position. Then press the credit/start button. Does the coin unit reset to the 1st position?

Does the AX relay move (trip/latch) during the reset?

Here's a video from Clay's Pin Repair Web site that explains the changeover to the AX relay system and how the AX relay works:

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

Since there was a long break, we should confirm the present status of the machine...

When you power on the machine, what happens? Are all the playfield lights and backglass lights turned on? Is the game over light on in the backglass area?

With credits showing on the credit unit, what happens when you push the start/credit button?

Can you start a game by manually pushing the S relay?

When you power on the machine, it should be in tilt mode - backglass lights on and playfield lights off.

As HowardR mentioned, refer to his photo of the schematic at post #25 that shows the start circuits...

When you press the start/credit button, does the V relay coil energize?

Since you said the coin switches are also not working, the problem might be with a switch in the first part of the start circuit. Check the following:

AX relay switch - orange wire and slate/white/red wire
Score motor switch 1C - maroon/green wire and slate/white/red wire

Make sure these switches are clean and adjusted properly.

The Q relay is the game over relay. The U relay is the first ball relay. The schematic will show a game that is reset with the ball in the shooter lane ready to play the 1st ball. Schematic is showing the U as energized at the start of a game, and the Q relay not energized at the start of a game. Check the following switch on the Q relay:

Q relay switch - slate/white wire and blue/white/red wire

Check the switch with the machine powered off. Switch should be in a normally open (NO) position.

The AX relay switches are responsible for de-energizing the Q relay and the U relay. If you manually operate the AX relay, do the Q relay and U relay de-energize? Also check the switch adjustment on all of the switches on the AX relay.

When you first power on the machine, is it still in tilt mode - backglass lights on, playfield lights off? When you first power on the machine, and it's in tilt mode, are Q relay and U relay energized?

Check the H relay switches to see if they are adjusted properly. Is the H relay energized after the machine is reset for a new game?

Still researching the Q relay and U relay operation...

For now, moving on to the next problem where the game stays on ball 1 after draining...

With the game reset, manually close the trough switch. When the trough switch is closed, does the P relay coil energize?

I could use a beer right now...

When the ball enters the outhole, does the bonus count down correctly and does the score motor run?

Looking at the circuit that sends power to the player unit solenoid. Check the following switches:

With machine powered off -
I relay switch - slate/yellow wire (gateway switch; normally closed)
U relay switch - slate/yellow wire and white/blue wire (normally open)
Score motor switch 2C - white/blue wire and yellow/blue wire (normally open)
P relay switch - yellow/blue wire and yellow wire (normally open)
BX relay switch - yellow wire and white/slate wire (normally closed)
Score motor switch 1A - white/slate wire and blue/white/red wire (normally open)

Make sure these switches are clean and adjusted properly.

Also, if you haven't done so already, check and clean all the Jones plugs on the machine. Since you said there was an issue with the coin door Jones plugs, there could be connection issues with the other Jones plugs in the machine.

For cleaning the Jones plug receptacles, you can roll up a small piece of 400 grit sandpaper to clean the inside of the receptacles.

When the 1st ball enters the outhole, does the player unit rotate? When the machine is reset, does the player unit rotate?

With the the machine powered off, manually rotate the player unit a few steps/clicks. Then power on the machine and reset the machine. Does the player unit rotate during the reset?

So, when you press the start button one time, the machine completely resets, the ball kicks out to the shooter lane and ball 1 is lit on the backglass? At that point, is the machine set for a 1 player game or a 4 player game?

There might be a problem with one of the score reel switches that is not allowing power to get to the player unit advance solenoid. I would use a jumper wire to bypass these score reel switches to see if one of the switches has a connection issue.

Power off the machine and connect one end of the jumper wire to score motor switch 1A with the blue/white/red wire, and connect the other end of the jumper wire to the add player unit solenoid with the brown/white/red wire. Power on the machine, reset the machine and see what happens.

If the game remains in 4 player mode after you reset the machine, then the coin unit is not resetting. Power off the machine and manually reset the coin unit to the first position. Then power on the machine and reset it. Does the game stay on 1 player mode after the machine is reset or does it count up to 4 player mode?

If the balls in play are not changing with the jumper wire attached, you'll need to jump at a different switch which is closer to the beginning of the circuit. We know P relay is working, so keep one end of the jumper wire on the add player unit solenoid with the brown/white/red wire and attached the other end of the jumper wire to the P relay switch with the slate/white/red wire. Then reset the machine and play a game to see if the ball in play will advance to the 2nd ball.

Apologies... I was working off a Royal Flush schematic, and a lot of the wire colors are the same as So76, but not in this part of the schematic...

On the P relay, attach the jumper wire to the yellow wire (next to the yellow/blue wire on the same switch stack/right side of photo).

The jumper wire is in the correct position...

The score motor keeps running, because the score did not completely reset. For now, just manually reset the score reel to zero.

With the all the score reels at zero, the coin unit reset to the first position, and the jumper wire removed, power on the machine and reset it. What happens during/after the reset?

The machine is probably set on free play mode. This is done by adjusting the zero position replay unit switch to the closed position. This shouldn't have any negative effects when troubleshooting.

Does top coil on the coin unit energize briefly and then release/de-energize during the reset? Or is the coil constantly energized? Is the 1 player lamp turned on in the backglass - 2, 3, and 4 player lamps are off?

Again, hook up the jumper wire to the add player unit coil and to the P relay switch - same color wires. If needed, manually reset the score reels to zero. Reset the machine and see what happens.

For the number of players choosen in a game, the 1 player lamp remains turned on during the reset? 2, 3, 4 player lamps are always turned off?

When you said the score motor keeps running when the machine clicks over to player 2, is this during the reset process when the player 2 score reel lamps will briefly turn on?

At this point, when the jumper wire is connected, the score motor will constantly run during the reset? When the jumper wire is disconnected, the machine will reset normally, the 1st ball will play normally, but the game will not go to 2nd ball status?

What happens now when you reset the machine without the jumper wire?

Researching more on how this machine changes to the differing balls in play, which is through the player unit. I'll post more info this evening...

Looking at the P relay again, when the trough switch (through switch) is closed when the ball kicks over to the shooter lane, does the P relay coil energize and quickly turn off? Or does it energize, lock on and remain energized?

After the 1st ball drains, and the game remains on the 1st ball (did not advance to 2nd ball; ball sitting in the shooter lane), go to the player unit and manually advance the player unit one step. Does the game remain on player 1 and show/light up ball 2 after you advance the player unit?

The P relay needs to energize and lock on starting with the 2nd ball. Reset the machine and play the 1st ball. When the 1st ball goes into the outhole, it will kick the ball over to the shooter lane and it will close the trough switch, which will energize the P relay coil. During the process of the 1st ball draining and the 2nd ball in the shooter lane, can you tell if the P relay energizes on/off quickly, or does it stay energized for 2-3 seconds, or is it constantly energized?

Make sure the following switches are clean and adjusted properly. Sometimes you'll need to "scrub" the switch contact with a Flexstone or paper fingernail file to get them thoroughly clean.

P relay switch - blue/white wire and maroon/green wire
Score motor switch 2B - maroon/green wire and slate wire.

Make sure the coin unit is reset and then reset the machine...

After cleaning/adjusting those switches, does P relay energize on/off quickly, or does it look like it stays energized for 2-3 seconds between the changing of the 1st and 2nd ball?

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