Williams Grand prix schematic question

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I just spent 4 hours working on a Grand Prix and it is worse now than when I started. My biggest problem is that the schematic does not match the wiring for the Coin relay coil. When credits are present, and the start button is pressed, the credit unit reset coil steps credits down 1 step. The EOS switch is a make/make. One half holds power on the credit unit reset coil. The other half holds the Coin relay coil until a process completes. The coin relay is not pulling in. I used a jumper from the credit unit reset eos switch to go directly to the Coin Relay coil. Still nothing. I know the EOS is live because it holds the credit unit reset coil pulled in until the eos switch is opened by hand.

My problem is that the COIN coil does not have any voltage on it to match the 'ground' coming from the credit unit reset coil EOS switch. The Coin relay circuit has a hold circuit through the switch stack of the Coin relay. If you manually activate the switch pack of the Coin relay, the relay should stay pulled in by the hold circuit. It does not because there is little or no voltage on the coil.

The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire. Is this a mis-print that anyone has dealt with before? Does anyone know where the red wire comes from?

I am hoping to avoid pulling off the waxed string and tracking the red wire by hand.

I found one red wire on the schematic. It goes to things like the extra ball relay and the ball index relay. These are things that should not be energized in game over mode. I found that if I reset the game over trip by hand that the Coin relay coil now has power to the point that it's holding circuit will now keep the coil pulled in.

Are there corrected schematics that anyone knows about anywhere?

Any suggestions would be appreciated.

pinworks

[Mark]

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)

I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.

As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.

/Mark

[[e-mail]]

Post by Mark

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)
I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.
As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.
/Mark

Mark, I agree with your assessment. However, that does not explain how the start button was working at the start of my tests. I should have mentioned that. The Coin relay should not be connected to the red wire that only goes live when the game is not in Game Over mode. I did move any wires and it worked before. That is what has me so puzzled. I am hoping for corrected schematics or an explanation of what I am missing.
As for the sanity check, I bypassed all the path from the yellow wire by jumpering from the EOS on the credit unit reset coil. I know it is connected to yellow because it holds the credit unit reset coil active until I do something to open the hold circuit.

Thank you for the reply.

Unless someone has a better idea, I am going to have to remove the wax thread bundling the red wire and trace it down. I find it hard to believe it is the same red wire that goes to the Game Over relay.

Pinworks

[Kerry Imming]

Post by ***@bellsouth.net

Post by Mark

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)
I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.
As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.
/Mark

Mark, I agree with your assessment. However, that does not explain how the start button was working at the start of my tests. I should have mentioned that. The Coin relay should not be connected to the red wire that only goes live when the game is not in Game Over mode. I did move any wires and it worked before. That is what has me so puzzled. I am hoping for corrected schematics or an explanation of what I am missing.
As for the sanity check, I bypassed all the path from the yellow wire by jumpering from the EOS on the credit unit reset coil. I know it is connected to yellow because it holds the credit unit reset coil active until I do something to open the hold circuit.
Thank you for the reply.
Unless someone has a better idea, I am going to have to remove the wax thread bundling the red wire and trace it down. I find it hard to believe it is the same red wire that goes to the Game Over relay.
Pinworks

The schematics look correct. I have seen notations on some schematics
that wire colors may have been substituted during manufacture.

Have you checked the other relay coils that should be on BLACK to see if
they are also on this RED wire? It seems more likely that this RED wire
might have been some previous repair, but surprising that is would be in
the wiring bundle then.

- Kerry

[[e-mail]]

Post by Mark

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)
I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.
As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.
/Mark

Mark, I agree with your assessment. However, that does not explain how the start button was working at the start of my tests. I should have mentioned that. The Coin relay should not be connected to the red wire that only goes live when the game is not in Game Over mode. I did move any wires and it worked before. That is what has me so puzzled. I am hoping for corrected schematics or an explanation of what I am missing.
As for the sanity check, I bypassed all the path from the yellow wire by jumpering from the EOS on the credit unit reset coil. I know it is connected to yellow because it holds the credit unit reset coil active until I do something to open the hold circuit.
Thank you for the reply.
Unless someone has a better idea, I am going to have to remove the wax thread bundling the red wire and trace it down. I find it hard to believe it is the same red wire that goes to the Game Over relay.
Pinworks

The schematics look correct. I have seen notations on some schematics
that wire colors may have been substituted during manufacture.
Have you checked the other relay coils that should be on BLACK to see if
they are also on this RED wire? It seems more likely that this RED wire
might have been some previous repair, but surprising that is would be in
the wiring bundle then.
- Kerry

Kerry,
It really looks like original wiring. The machine is not at my house and I did not check continuity from the Extra Ball relay red wire to the Coin relay red wire so I do not know they are the same. I was hoping someone had encountered this before. It does not appear so.

Thanks
Pinworks

[pinworks]

Post by ***@bellsouth.net

Post by Mark

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)
I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.
As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.
/Mark

Mark, I agree with your assessment. However, that does not explain how the start button was working at the start of my tests. I should have mentioned that. The Coin relay should not be connected to the red wire that only goes live when the game is not in Game Over mode. I did move any wires and it worked before. That is what has me so puzzled. I am hoping for corrected schematics or an explanation of what I am missing.
As for the sanity check, I bypassed all the path from the yellow wire by jumpering from the EOS on the credit unit reset coil. I know it is connected to yellow because it holds the credit unit reset coil active until I do something to open the hold circuit.
Thank you for the reply.
Unless someone has a better idea, I am going to have to remove the wax thread bundling the red wire and trace it down. I find it hard to believe it is the same red wire that goes to the Game Over relay.
Pinworks

The schematics look correct. I have seen notations on some schematics
that wire colors may have been substituted during manufacture.
Have you checked the other relay coils that should be on BLACK to see if
they are also on this RED wire? It seems more likely that this RED wire
might have been some previous repair, but surprising that is would be in
the wiring bundle then.
- Kerry

Kerry,
It really looks like original wiring. The machine is not at my house and I did not check continuity from the Extra Ball relay red wire to the Coin relay red wire so I do not know they are the same. I was hoping someone had encountered this before. It does not appear so.
Thanks
Pinworks

Problem solved: The game had a birth defect. The coil labels for the three coils in the right far corner of the bottom of the cabinet were correct. Someone at the Williams factory put the same label for those three coils(one piece label) on the left edge center. So there were two coils labeled COIN. I happened to see the mislabeled relay first. The correct coil in the back left corner had the right color wire on it.
I'd really like to be able to have a word with the person who inspected that game!
I discovered the problem because I had worked on a Grand Prix the week before and the relay positions did not match what I had expected to find from previous work on the mis-labeled machine.
I feel sure the incorrect label had been installed at the factory. It was fastened in place by the small staples that Williams used for that purpose. From now on, I will double check with the manual if one is available.

Thanks for all your efforts
Pinworks

[John Robertson]

Post by pinworks

Post by ***@bellsouth.net

Post by Mark

Post by ***@bellsouth.net
The coin relay is not pulling in.
The schematic shows that the coin relay is connected to the black primary wire coming from the transformer. The coil is actually connected to a thick red wire.

If you follow the black wire down the right side of the schematic, it
goes through switches on the Game Over, Reset and Tilt relays before
emerging as a Red wire, or the power rail that provides power to the
playing part of the game. The black wire is more for parts of the game
that have to be available between games (coining up, reset, etc.)
I can't explain how the Coin relay ended up on the wrong power rail, but
I wonder if you removed the red wire from its coil solder lug and
jumpered the black wire to the solder lug instead (as shown on the
schematic) if it would start working.
As a sanity check you might want to verify the rest of the Coin relay
circuit first by ohming out the path from the yellow wire power rail
through the Score Motor Make/Break switch and Credit Unit EOS switch.
/Mark

Mark, I agree with your assessment. However, that does not explain how the start button was working at the start of my tests. I should have mentioned that. The Coin relay should not be connected to the red wire that only goes live when the game is not in Game Over mode. I did move any wires and it worked before. That is what has me so puzzled. I am hoping for corrected schematics or an explanation of what I am missing.
As for the sanity check, I bypassed all the path from the yellow wire by jumpering from the EOS on the credit unit reset coil. I know it is connected to yellow because it holds the credit unit reset coil active until I do something to open the hold circuit.
Thank you for the reply.
Unless someone has a better idea, I am going to have to remove the wax thread bundling the red wire and trace it down. I find it hard to believe it is the same red wire that goes to the Game Over relay.
Pinworks

The schematics look correct. I have seen notations on some schematics
that wire colors may have been substituted during manufacture.
Have you checked the other relay coils that should be on BLACK to see if
they are also on this RED wire? It seems more likely that this RED wire
might have been some previous repair, but surprising that is would be in
the wiring bundle then.
- Kerry

Kerry,
It really looks like original wiring. The machine is not at my house and I did not check continuity from the Extra Ball relay red wire to the Coin relay red wire so I do not know they are the same. I was hoping someone had encountered this before. It does not appear so.
Thanks
Pinworks

Problem solved: The game had a birth defect. The coil labels for the three coils in the right far corner of the bottom of the cabinet were correct. Someone at the Williams factory put the same label for those three coils(one piece label) on the left edge center. So there were two coils labeled COIN. I happened to see the mislabeled relay first. The correct coil in the back left corner had the right color wire on it.
I'd really like to be able to have a word with the person who inspected that game!
I discovered the problem because I had worked on a Grand Prix the week before and the relay positions did not match what I had expected to find from previous work on the mis-labeled machine.
I feel sure the incorrect label had been installed at the factory. It was fastened in place by the small staples that Williams used for that purpose. From now on, I will double check with the manual if one is available.
Thanks for all your efforts
Pinworks

Factory manuals aren't perfect either! High Speed manual doesn't both to
show you have the Special Solenoids get their power - turns out to be F4
and that a pin shown as grounded on the supply actually is the power
connection for that fused output.

I'm sure it has been caught before, but I'm updating my schematics and
will send a modified book to IPDB so they can add it to the site. This
is lightly mentioned in the amendments PDF on IPDB.

John :-#)#