IWB DMX problem

[ekul1978]

Just looking for help with things to maybe look for - we have had our new lighting bars wired in etc but left the DMX to me.  Wired in all 5 from the end box but can only get 4 of them to work.  I've had a look at the cables, opened up the first DMX box and everything seems ok.  Swopped wires around incase colours were not correct but still nothing.  Only thing I can think is maybe their is a problem with the cable I have wired from the end box.  Just looking for any hints as to maybe what to look for? what to test?  

[sameness]

Test for continuity. Plug a working cable into the outlet so you can trail back to the box and use a multimeter or sniffer to see if theres continuity in the cable on each wire 

[DrV]

3 hours ago, sameness said:

..see if theres continuity in the cable on each wire...

At the same time check for isolation between each pin and the others.

[ekul1978]

Thanks. Not got a multimeter at the moment. Should really buy one I think. 

[Don Allen]

I use a network cable tester similar to this one, Multicomp PRO 72-9946, this is a UK version, to test DMX, mic and talkback cabling for wiring errors. I have made XLR3 and XLR5 male and female adaptors. It is cheap, easy to use, you can plug it is at one end and go to see what is happening at the other end. I also have a signal tracer for trying to locate sockets.

[themadhippy]

If you find yerself testing cables regularly then get a megger, cant beat a dose of 500v up a cable (or the apprentice) to find most faults.

[DrV]

3 hours ago, themadhippy said:

If you find yerself testing cables regularly then get a megger, cant beat a dose of 500v up a cable (or the apprentice) to find most faults.

BUT, if you use it to test coax cables, be sure to discharge the cable afterwards. I once made up a set of RGB cables and made the mistake of plugging them into a rather expensive graphics card only a few minutes after testing. The capacitance of the cable had stored enough energy to dispatch the card. I did that only once.

[sunray]

4 hours ago, DrV said:

BUT, if you use it to test coax cables, be sure to discharge the cable afterwards. I once made up a set of RGB cables and made the mistake of plugging them into a rather expensive graphics card only a few minutes after testing. The capacitance of the cable had stored enough energy to dispatch the card. I did that only once.

I would have never given that a thought.

[themadhippy]

Quote

BUT, if you use it to test coax cables, be sure to discharge the cable afterwards

same with pyro (micc), often you'd  put the gland on and test  as part of the first fix and stuff the bare ends in the back box, waiting for some innocent plasterer or painter to push them out the way