Help with this wiring diagram.

[coleco1981]

I'm in the middle of building a pengo wiring harness from scratch - its coming along pretty well thanks to people sending me pictures of their original harness. Its not going to look identical but I think it will look pretty close.

Anyway... I'm stuck on understanding how the sound pot is wired in. It looks like there is a shielded audio cable involved - red, black, and the shielding going to a 10k volume pot. Can someone explain to me what these rings on the diagram mean (see attached)?


My belief is that the circle just shows that those 2 wires should be shielded, then shielding metal should be connected/combined to PIN 10 which is a ground through the passthrough amp connector. I think this is done on both sides of the connector?

Then looking further down (see separate diagram that is zoomed out, the shielding at at the edge connector is run to PIN B, then jumped to PIN 2, which then goes into a ground on a PSU (pin 6). Phew...

This just seems pretty complicated to follow and it would be very helpful if someone who understands this diagram better then I do, confirm if this is how I should wire it. I'd really like my pengo sound to work and I certainly wouldn't want to blow my sound amp because of some stupid wiring!


I also included a picture that was taken for me to assist, its hard to tell from the picture where the shielding is connecting to but I think I circled it.

 

[coleco1981]

bonus question that is related, I ordered this cable to replicate what they used. Its very thin wire but I think it will be crimp able. Does this look right? We will see:

Amazon.com: CBAZY 2547 24 AWG Control Cable Copper Wire Shielded Audio Cable Headphone Cable Signal Line 2-core 8 Meter Grey: Home Improvement

 

[ArcadeTechGW]

From my electronics training, that circle is the indication of a shielded cable.

The lead off is the ground path.

It's unusual to ground both ends in the nuclear business, because you can get circulating currents. I think they mitigated that with the 1K resistor on the right side to ground to dissipate any stray voltage as heat.

I'm retired now, so I don't have access, but I've seen this thousands of times in both aviation and nuclear power, and some arcade games.

 

[coleco1981]

From my electronics training, that circle is the indication of a shielded cable.

The lead off is the ground path.

It's unusual to ground both ends in the nuclear business, because you can get circulating currents. I think they mitigated that with the 1K resistor on the right side to ground to dissipate any stray voltage as heat.

I'm retired now, so I don't have access, but I've seen this thousands of times in both aviation and nuclear power, and some arcade games.

There is a 1k resistor that is supposed to be hanging off the pot?

I really wish I could see in person an original pengo cabinet - I'm confused.

I'm also confused on everything that I've highlighted here. Are these all physical wires that are jumpering pins or is this just an indication that they are connected through the pcb?

 

[ArcadeTechGW]

Here is an example I found in an avionics manual I had handy.

 

[ArcadeTechGW]

Sorry, I don't know where I came up with 1K.

But a resistor is shown. I circled it to help.

 

[ArcadeTechGW]

There is a 1k resistor that is supposed to be hanging off the pot?

I really wish I could see in person an original pengo cabinet - I'm confused.

I'm also confused on everything that I've highlighted here. Are these all physical wires that are jumpering pins or is this just an indication that they are connected through the pcb?

Yes, that is the schematic symbol for installed jumpers.

Depending on the size of the wire and pin, you may be able to crimp the wires together in the connector.

Someone here must have a Pengo. Try VAPS and see if you can find someone to take a picture, or if local, to let you go look.

Pengo is a game I never had the chance to work on.

 

[ArcadeTechGW]

There is a 1k resistor that is supposed to be hanging off the pot?

I really wish I could see in person an original pengo cabinet - I'm confused.

I'm also confused on everything that I've highlighted here. Are these all physical wires that are jumpering pins or is this just an indication that they are connected through the pcb?

And I just saw this which means the two wires indicated are twisted together for some reason.

 

[ArcadeTechGW]

I found someone bringing a Pengo back. Maybe you could reach out for photos. (Or maybe this is you?)

Pengo

 

[ArcadeTechGW]

And this guy had problems with static and took this picture of the back of the volume pot.

https://www.rotheblog.com/2007/06/arcade/pengo-sound-controls-inside-coin-door/


The gray wire is the shielded cable. Unfortunately, I can't see where the resistor is grounded, but it looks like it runs to one of the potentiometer lugs.

This gives you a couple of people who have documented rebuilds. Maybe one can help you or let you see what you need to see?

Building a wiring harness is not for the uninitiated. Think of how the companies did it.

They had a jig on plywood, with all the routes at the right lengths, and then spools of the right wire.

They would run all the wires (say you needed a green, green with blue stripe, yellow, yellow with brown stripe, orange, gray with pink stripe - you'd grab all of these and then pull them through the "guides" until you reached the end point. Then you cut the wires off the spools. And repeat for the next runs until you had populated the playfield.

From there you would wax tie or tie wrap the bundles and then start putting connectors on. It's very labor intensive.

 

[coleco1981]

Arcadenut sent me some pictures of his edge connector, he is saying there arn't jumpers on the connector. Further investigation continues.

 

[bakerhillpins]

And I just saw this which means the two wires indicated are twisted together for some reason.

Twisted pair is done for noise rejection. The twisting is not random, it's got specs too. All modern day Ethernet cable dtakes advantage of this behavior.

 

[coleco1981]

And this guy had problems with static and took this picture of the back of the volume pot.

https://www.rotheblog.com/2007/06/arcade/pengo-sound-controls-inside-coin-door/
View attachment 479303

The gray wire is the shielded cable. Unfortunately, I can't see where the resistor is grounded, but it looks like it runs to one of the potentiometer lugs.

This gives you a couple of people who have documented rebuilds. Maybe one can help you or let you see what you need to see?

Building a wiring harness is not for the uninitiated. Think of how the companies did it.

They had a jig on plywood, with all the routes at the right lengths, and then spools of the right wire.

They would run all the wires (say you needed a green, green with blue stripe, yellow, yellow with brown stripe, orange, gray with pink stripe - you'd grab all of these and then pull them through the "guides" until you reached the end point. Then you cut the wires off the spools. And repeat for the next runs until you had populated the playfield.

From there you would wax tie or tie wrap the bundles and then start putting connectors on. It's very labor intensive.

Yep saw that and alot of his other blog post related to pengo - I sent an e-mail to Jeff to ask some questions.

 

[coleco1981]

I knew recreating the harness wasn't going to be fun - finding the right supplies is expensive and frustrating, but I thought deciphering where the wires go would have been pretty straight forward.

The CP wiring is done, power wiring is done - coindoor/service panel/counter wire, video wiring, and terminating the edge connector is all that is left!

 

[bakerhillpins]

WRT the original question... Yes, the cable is simply 2 strand shielded cable, probably red/black in a gray jacket. It will have a non-insulated ground conductor in it too. You can pick it up at home depot for something like $0.23 a foot.

It looks just like all the other volume pot wiring diagrams of that era.. here's a Wms Stargate for example:


The only difference with your setup is that there is a level shifting resistor between the pot and ground (shield) which effectively limits the volume.

 

[bakerhillpins]

And this guy had problems with static and took this picture of the back of the volume pot.

You can see the gray jacketed wire I'm talking about here:

 

[coleco1981]

WRT the original question... Yes, the cable is simply 2 strand shielded cable, probably red/black in a gray jacket. It will have a non-insulated ground conductor in it too. You can pick it up at home depot for something like $0.23 a foot.

It looks just like all the other volume pot wiring diagrams of that era.. here's a Wms Stargate for example:
View attachment 479310

The only difference with your setup is that there is a level shifting resistor between the pot and ground (shield) which effectively limits the volume.

So this diagram looks very straight forward, the shield is connected to pin 4. In mine I *think* its spliced in to pin 10 sharing it with a ground wire.

 

[coleco1981]

yep - got that, I think the cabling I bought from amazon will match.

 

[bakerhillpins]

So this diagram looks very straight forward, the shield is connected to pin 4. In mine I *think* its spliced in to pin 10 sharing it with a ground wire.

Yes, that appears to be the case.

 

[ArcadeTechGW]

Twisted pair is done for noise rejection. The twisting is not random, it's got specs too. All modern day Ethernet cable dtakes advantage of this behavior.

The key is to duplicate the twist right, or you won't get the effect.

To do that, you'll need a picture of the wire, and a scale next to it so you can see the turns per inch.