Test ribbon cable continuity

Thread Starter

superway

Joined Oct 19, 2009
125
Hi,

I plan to build a small test fixture to test continuity for ribbon cable 40 pins or 50 pins. Can anyone know out there any pre-built device or any other devices can be used to check continuity for ribbon cables? like LEDS or display.

Thanks

Ken
 

Thread Starter

superway

Joined Oct 19, 2009
125
I know the circuit that Seldons sent to me; it is controlled LED on and OFF.

It is not my question that I am trying to ask. My question is, if I have
40-pin Ribbon cable and both side of cable has 40-pin connector. In
order to ohm out for continuty between 2 sides, I can use Fluke meter to check it, but it takes too long to do it every pin.

If someone knows, is there any electronic device tester or circuitry to perform continuty check with thousands of Ribbon cables in production?

Thanks
 

tshuck

Joined Oct 18, 2012
3,534
I know the circuit that Seldons sent to me; it is controlled LED on and OFF.

It is not my question that I am trying to ask. My question is, if I have
40-pin Ribbon cable and both side of cable has 40-pin connector. In
order to ohm out for continuty between 2 sides, I can use Fluke meter to check it, but it takes too long to do it every pin.

If someone knows, is there any electronic device tester or circuitry to perform continuty check with thousands of Ribbon cables in production?

Thanks
There probably is a device that measure resistance of multi-conductor ribbon cable, but it is also probably custom made and costs lots of money.

You could always make one...
 

sheldons

Joined Oct 26, 2011
613
ok if you wish me to design a peice of equipment to display with leds continuity between either end of a wire that basic circuit will do just that,obviously depending how many way your ribbon connector/wiring harness is means it needs to be duplicated for each wire-you could do this with one circuit as shown and a rotary switch to test each wire in turn manually.
having said that ,you could use a 4017 etc to drive each set of cables in turn at whatever speed you want-orrrrr even simpler use a single led per wire,and just connect your cable/ribbon up and that will give you a visual indication of wether you have an oc lead-lead thats good etc,for the problem of cables shorted to each other im sure a circuit to check for that also is fairly easy to build in to the design-of course you need not go down the discrete component route im sure a pic or some other programmable ic could be used as well-again depends how far you want to go,if it was me id use a 4017 counter and a few extra parts to check each wire in turn ,if shorts between wires were a problem a bit of extra gating can be used to show that as well
 

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sheldons

Joined Oct 26, 2011
613
I would go for a 4017 and discretes to test your cables and of course it can be customised to suit how ever many way your ribbon /cable harness may be .....
 

BillB3857

Joined Feb 28, 2009
2,546
Take a couple of sockets and wire so that all wires will be in series when the cable is plugged in. Battery, LED and resistor will show continuity. Then, take another connector and tie all the odd pins together and all the even pins together. With one end of the cable plugged in, the bussed pins should still show an open condition. DONE!
 

PackratKing

Joined Jul 13, 2008
847
Take a couple of sockets and wire so that all wires will be in series when the cable is plugged in. Battery, LED and resistor will show continuity. Then, take another connector and tie all the odd pins together and all the even pins together. With one end of the cable plugged in, the bussed pins should still show an open condition. DONE!
great ! One question tho' Setting connectors up in that manner makes the ribbon one long wire... How do you judge which wire is open if no continuity...??
 

sheldons

Joined Oct 26, 2011
613
Its all in the way you wire the sockets where the test cables plug in....as regards the continuity problem you could wire it like this as an example.....
 

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thatoneguy

Joined Feb 19, 2009
6,359
You could make one end with 40 LEDs on a board with a socket, the other end would be a voltage source + clock + 5 1-8 multiplexers, cycle through at maybe 0.5Hz and watch the LEDs, that solution would show both continuity, as well as any wires that were shorted together.
 

BillB3857

Joined Feb 28, 2009
2,546
great ! One question tho' Setting connectors up in that manner makes the ribbon one long wire... How do you judge which wire is open if no continuity...??
Sorry for the delay. I've been withoutout internet service for a few days.
To answer your question, once you know you have an open, go wire by wire to find the problem. The connector idea is just a quick GO/NO-GO test. If NO-GO, then standard troubleshooting takes over.
 

Thread Starter

superway

Joined Oct 19, 2009
125
Each counter IC 4017 has 10 outputs and If I use to test 40-pin ribbon cable ( 20 by 20), so do I have to use 4 counter 4017 Ics?

Thanks for all responses
 

thatoneguy

Joined Feb 19, 2009
6,359
You could use 1 4017, and have the outputs drive transistors that in turn power all 4 LEDs. 10 Transistors, 1 4017, 1 clock source (555 or similar slow clock)
 

Thread Starter

superway

Joined Oct 19, 2009
125
I attached a rough schematic to test 40-pin ribbon cable. On the ribbon cable has 2 rows, first row is odd number and second row is even number.
This is can be test if any wire is missing or bad crimp and pins short out between odd wire and even wire ( LED turns on not property if short out the wires).
Test cable will connect between CONN 1 and CONN 2 on schematic.

Please correct any error on sch.

Thanks
 

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BillB3857

Joined Feb 28, 2009
2,546
When dealing with ribbon cable, other than finding any open or short, is it beneficial to know exactly which wire is bad? Most connections on insulation displacement cables require removal of the offending connector. There is a 50/50 chance of guessing which one is the offender. When we make cables we use the GO/NO-GO test and if it fails, cutoff both connectors and re-install. Time to do otherwise exceeds the cost of the connectors. What's next? Spend a lot of time to find the exact distance from the connector the failure is? Just my opinion.
 
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