pinballs why are they wired the way they are?

[pinball god]

Again I'm no expert, but are pinballs wired the opposite to most electronic stuff. Are they 'negatively' wired in that making ground activates components like coils. Sounds silly in that it wouldn't take much for a person to act as the connecting circuit for say activating a coil etc. Lots of metal parts on a pinball suited to that like rails.

If my observation is correct, why did they go for this method?

Also on the wiring, take a coil, why do they use a smaller gauge wire for the return? Does it not receive the same power as its larger brother? If its for easy recognition, wouldn't the wire colour coded suffice?

Thanks

[Homepin]

The most common switching device is an NPN transistor and they operate by switching a load to ground (any load, lamp, coil, etc) Similarly with MOSFETs.

There are devices that are "high side" switches that switch to the positive rail but they are more expensive, less reliable and require more circuitry to drive them.

Down to price and reliability.

It is well known by seasoned techs that PNP transistors are the first ones you suspect if you have a weird issue with any electronics (not just pinball machines). NPN are far more robust and reliable.

[DSB]

Also on the wiring, take a coil, why do they use a smaller gauge wire for the return? Does it not receive the same power as its larger brother? If its for easy recognition, wouldn't the wire colour coded suffice?

You can almost see your mind ticking over  . This is a question that a good electrical apprentice will ask in about their second year. It is not so much the power but the current each coil draws or allows to pass though it when activated. Larger wires handle more current.  The return can be smaller because it only needs to handle the current returning from that particular coil. The supply on the other hand feeds several coils so potentially needs to handle the current for several coils added together and a good designer would size the wire to handle the current if say all the coils were on. You could indeed reduce the supply wire size as you go down the loom as the potential current draw is reduced but for ease of install it is kept the same.

[Marty Machine]

The most common switching device is an NPN transistor and they operate by switching a load to ground (any load, lamp, coil, etc) Similarly with MOSFETs.

There are devices that are "high side" switches that switch to the positive rail but they are more expensive, less reliable and require more circuitry to drive them.

Down to price and reliability.

It is well known by seasoned techs that PNP transistors are the first ones you suspect if you have a weird issue with any electronics (not just pinball machines). NPN are far more robust and reliable.

ditto....LOW-side switching has always been preferable, it's easier to 'sink' current (NPN) instead of  'source' it (PNP).

[pinball god]

Also on the wiring, take a coil, why do they use a smaller gauge wire for the return? Does it not receive the same power as its larger brother? If its for easy recognition, wouldn't the wire colour coded suffice?

You can almost see your mind ticking over  . This is a question that a good electrical apprentice will ask in about their second year. It is not so much the power but the current each coil draws or allows to pass though it when activated. Larger wires handle more current.  The return can be smaller because it only needs to handle the current returning from that particular coil. The supply on the other hand feeds several coils so potentially needs to handle the current for several coils added together and a good designer would size the wire to handle the current if say all the coils were on. You could indeed reduce the supply wire size as you go down the loom as the potential current draw is reduced but for ease of install it is kept the same.

so putting a heavier wire would not have been a problem. I find the lighter gauge wire on a coil seems to be the one most often that will break off. Dunno if a larger gauge would alleviate this problem.

[Homepin]

I think you will find the reason it breaks off is because it is tinned a fair way up the wire and so offers no flexibility therefore it acts like a solid strand of a single wire and has no give.

Vibration and movement cause flexing of the stiff, tinned wire and so it snaps.

It really doesn't have a lot to do with the gauge of the wire used IMO more HOW it has been connected.

I feel that most harnesses are inadequately supported with cable clamps etc and wires are just left "hanging in the breeze" this is the main cause of wiring problems as I see it.

Perhaps use 20 or so small cable ties and prevent the wires from flapping about would do more than replacing them?

[pinball god]

I think you will find the reason it breaks off is because it is tinned a fair way up the wire and so offers no flexibility therefore it acts like a solid strand of a single wire and has no give.

Vibration and movement cause flexing of the stiff, tinned wire and so it snaps.

It really doesn't have a lot to do with the gauge of the wire used IMO more HOW it has been connected.

I feel that most harnesses are inadequately supported with cable clamps etc and wires are just left "hanging in the breeze" this is the main cause of wiring problems as I see it.

Perhaps use 20 or so small cable ties and prevent the wires from flapping about would do more than replacing them?

thanks Mike will try. Always looking for explainations to problems and seeing if they could have been avoided.

[DSB]

Correct! Putting a heavier gauge wire will do no harm but increase the cost of the machine to build for the manufacturer but I agree with Mike, How the wire is terminated will have a lot to do with mechanical strength. You want to avoid losing or nicking wire strands when stripping and don't strip the wire to far. It is difficult I know but also avoiding dangling the coil by the wires when working on an assembly will help.