Repairing audio/video leads

[M.Joshi]

I often receive audio and video cables that are either intermittent, shorted or broken at some point along the length. At the moment, I have quite a few XLR microphone cables. What causes an XLR cable to become shorted across all the cores along its length?

Is there an easy way to pinpoint where the intermittent connection is or where it is shorted/broken along the cable?

I am aware of TDR techniques but wondered if there was a simpler method - more for my curiosity rather than anything else.

 

[Tony Stewart]

not something I have tried , but a wireless sender conducting at one end is used by telephone techs to trace a short
.... with a sender at one end disconnected from use and walk along the path with portable Rx.
I use a CC power supply and estimate the wire length from gauge to determine where the short may be. On a circuit board, I fuse out a whisker short with a large charged cap.

For an open cct. a HV low current source can create an arc which can be detected by AM radio.

Causes: ask the roadies.

 

[KeepItSimpleStupid]

Well, with an Ethernet cable, I have one of those old LED based tester like things that had normal/rev depending on LED color.
The wiremapper is useless unless it's broken. I use long packet pings initially to help identify a bad cable.

So, there are cable testers, but I doubt they really have the ability to detect intermittents. Therefore a simple light with a current source and manually flexing the cable starting at the ends seems to work best. You can even look at the link light for an Ethernet cable.

TDR's are not very effective with long cables. I do PLAN to TDR my cable runs at some point, but I don;t have enough of them yet. Most of my Ethernet problems have been at the connector and the little tool works when you have the whole length in your hand.

 

[Tony Stewart]

I wonder if the TDR included in my Asus BIOS that indicates Ethernet length to 0.1m resolution could be modified with a connector adapter to measure cable faults. In this case can be enabled in BIOS to check working Ethernet cable lengths.

 

[diy didi]

TDR works. BUT, I think a capacitance meter would work best. Measure a good piece of wire at one end. Divide this into the length, and you have you pF rating per inch/ cm.

 

[Tony Stewart]

TDR works. BUT, I think a capacitance meter would work best. Measure a good piece of wire at one end. Divide this into the length, and you have you pF rating per inch/ cm.

Or measure open circuit capacitance from both ends and the ratio will determine position of the open circuit.