How do I identify pin 1 on a ribbon cable connector?

I have a ribbon cable that is not labeled and does not have a notch to prevent it from being installed backwards. How can I identify which pin is #1 on the connector?

Axxmasterr

Posted 2009-07-31T19:33:32.880

Reputation: 7 584

Answers

Pin 1 on a ribbon cable (the cable itself, not the terminators) is usually colored differently than the other pins - often red.

sangretu

Posted 2009-07-31T19:33:32.880

Reputation: 742

This is correct. – Troggy – 2009-07-31T19:37:36.023

It is, so long as you then know what pin #1 on the socket is... – Alistair Knock – 2009-07-31T19:40:39.277

3I'm assuming you have an IDE (ribbon) cable so, typically on motherboards, they'll mark a '1' on the board to indicate pin #1. For IDE cables, newer motherboards have a open tab in the connector so that the cable you insert into the interface can only face the correct way. The interface on the cable will usually have filling tab to eliminate confusion. – osij2is – 2009-07-31T19:46:45.017

See which edge of the cable (the cable, not the connector) is painted.

JCCyC

Posted 2009-07-31T19:33:32.880

Reputation: 2 143

Usually flat cable has one of it strand with a colored strips (usually red). So pin #1 will be on that side. if the pins are not lined up in the connector it will be the one the furthest to the side.

Pierre-Luc Simard

Posted 2009-07-31T19:33:32.880

Reputation: 771

Im not sure why sangretus response is doing so well. According to your post the ribbon is not marked. Additionally, the cable is just a wire so "wire #1" is arbitrary.

On the motherboard side osij2is is correct, they should have a #1 printed next to the terminal. On the other side your hardware user manual should help you determine where pin #1 is.

Kells

Posted 2009-07-31T19:33:32.880

Reputation: 1 008

That being the case (and I'm not equipped to say that it is), it then doesn't matter which way you connect the notchless/pinkless/labelless cable, so long as both ends are oriented toward pin #1 correctly, and therefore you are more correct. – Alistair Knock – 2009-07-31T20:07:34.030

You could use a multimeter to identify it, and the label/mark it for future use.

DHayes

Posted 2009-07-31T19:33:32.880

Reputation: 2 103

Won't do you any good when the other 30 or so pins also have voltage on them. – Alex S – 2009-07-31T19:54:12.817

From where? The intent is to test the cable directly, not while the cable is connected to anything. – DHayes – 2009-08-03T12:14:48.737