Ribbon cable tester

mhaaland

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Today, while repairing a Ms Pac board, I grabbed this little guy and found a customer's bad cable, made me think that it might be of interest to see here.

I started using this in 2006, I made 5 prototype PCBs, but only populated this one. It tests Ms. Pac 40 pin ribbon cables and 50 pin interconnect cables. The switch on the lower left is the ON/OFF switch, the lower right corner chooses the 'bank' of pins you want to test. Set to the left, it checks one every other wire in the ribbon cable, set it the other way to test only the other 1/2. The idea is that if you have an open wire, the LED for that wire won't light. If an LED lights on the side NOT being tested, you have a miscrimped connector. This is to catch shorted wires in a connector. For convenience, it is all powered off our JAMMA bench test jigs.

We use this on every Ms Pac ribbon cable and every DK/Galaga interconnect ribbon cable we build. I use it to test suspect ribbon cables on Ms. Pac pcbs also.

Keeps miscrimped cables from going out the door. And helps me detect suspected bad cables while doing repairs.
 

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thats pretty cool and handy Mike. i sure could have used one of those over the years. great job and tool.
 
Today, while repairing a Ms Pac board, I grabbed this little guy and found a customer's bad cable, made me think that it might be of interest to see here.

I started using this in 2006, I made 5 prototype PCBs, but only populated this one. It tests Ms. Pac 40 pin ribbon cables and 50 pin interconnect cables. The switch on the lower left is the ON/OFF switch, the lower right corner chooses the 'bank' of pins you want to test. Set to the left, it checks one every other wire in the ribbon cable, set it the other way to test only the other 1/2. The idea is that if you have an open wire, the LED for that wire won't light. If an LED lights on the side NOT being tested, you have a miscrimped connector. This is to catch shorted wires in a connector. For convenience, it is all powered off our JAMMA bench test jigs.

We use this on every Ms Pac ribbon cable and every DK/Galaga interconnect ribbon cable we build. I use it to test suspect ribbon cables on Ms. Pac pcbs also.

Keeps miscrimped cables from going out the door. And helps me detect suspected bad cables while doing repairs.

Cool! I want one! Please say you'll take my money and make me one.
 
Mike, so, since it can do 40 pins, it can also test any other / smaller idc to idc test cables - only using the leds that would correspond to the pins under test - correct? (if one removes any polarization ribs if present)
difficulty to adapt to a battery only power supply in lieu of a jamma rig to supply power for portability is?
 
It will do 50 pin idc cables and... Yes, it does work for smaller keyed IDC cables, just center them on the key. It may work with one of those 3 battery packs. Lemme give that a try today and see.
 
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interested price dependent of course, but looks like you already have more interest than boards
looks pretty handy
 
I was just looking up this very thing...

Very elegant solution...

But whats the zif socket for?
 
I was just looking up this very thing...

Very elegant solution...

But whats the zif socket for?
Thank you!

The ZIF sockets are for dip plugs, like the mspac ribbon cables. There are two of them. They wont wear out like a socket does over time. I just got in my batch of zif sockets to build these out. Now i need time. :)
 
Gotcha i forgot about that. Didnt cross my mind at 1am haha

Mike, if you are not going to build more of these assembled, as i understand it is a niche market.

Could you do a kit, as I was going to build one anyway.

If not, please msg here or pm. There was a schematic posted on all about circuits circuitry forum from 2013 I was going to use.



I don't want to waste time reinventing the wherl when i can give you my money.

P.s. I still desire your galaga adapter...
 
Let me source some zif sockets and I'll build what I have, 4 units.
Mike, it would be cool if you could make this also able to test a jamma harness. It would help to diagnose an edge connector or the harness by pressing the buttons while inside a cabinet. (just as if the jamma harness was just a large ribbon cable...)
 
Mike, it would be cool if you could make this also able to test a jamma harness. It would help to diagnose an edge connector or the harness by pressing the buttons while inside a cabinet. (just as if the jamma harness was just a large ribbon cable...)
Nice idea. At the moment, nothing but +5 and ground are used to power it. Nothing else is hooked up to the edge connecter.

I've got my zif sockets in now.
 
These simple testers work for opens but how do you test for adjacent shorts.

Some seller was recently clearing out a bunch of new B&K Precision 205's at $49 and this included connector adapter boards. These test for opens and shorts for cables of up to 64 conductors or 128 test points. I bought one - they are awesome!

Watch ebay for these - they pop up often.
 
As i stated in my long winded initial post, if a pin lights up on the column not under test you have a short.
 
But on a ribbon cable such as a 34 pinner -- you're testing all 34 conductors at once. You need to step them to test individual conductors or at least alternate the rows.

With a bit of fiddling, there is a way to do this with two tests on these simple boards but they need to be routed correctly.
First test for half the conductors, second test does the other half. Since a ribbon cable can only short to the next adjacent pin (in theory) - cut power to every other pin. If two adjacent LEDs lit up then you had a short. I used to have a fixture that worked in this manner, tossed it when I bought the new scanner... but this method worked quite well.

Hard to tell if that is how yours works but I can easily tell the Anarchy PCB tester mentioned doesn't check for shorts.

Fortunately for users - opens are the most common issue. But those of us that make and sell cables, we need to test for both.

***************************

Reread your first post -- your test fixture works in the same manner that my original fixture worked. This turned out being a quite effective test.
 
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