Club install dance floor movers + addition - DMX problem

Shane Presley

Shane Presley

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Jan 12, 2011
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Ottawa, Ontario, Canada
www.bssproductions.com
So I'd like to bounce my problem off you guys and hopefully come to some points I can check. I have a club install here is the layout



Light jockey to 15' DMX cable - into 50' Mic cable (through the ceiling ) to short dmx cable(s) through the dance floor lighting.

Dance floor is 4 x technobeams + 1 minimac. Termination on the last t-beam. This rig has been working for the past few months. I was asked to add some more movers to another part of the club so 3 x trackspots comes into play.

I removed the terminator, and added (using mic cables cause it's all I had) I tested the trackspots addressing and mic cables on the ground before installing them with light jockey

So from the last t-beam 50 ft mic cable to first t-spot,

25ft mic cable to next t-spot, 25 ft to the next t spot, termination.



Here's the symptoms. The technos won't work when the t-spots are in line and not without termination in the last trackspot.

the t-spots won't work with termination.



Each ''loop'' will work independently (t-spot loop or techno loop)



I suspect it's either a bad cable, or a phase reverse in the cabling. I also didn't know if using dmx + mic cable together would affect it.

Obviously it would be best to have all dmx cable, and that's what I'll be doing, this just needed to be up and running ASAP.

lighting guru thoughts ?







 
Re: Club install dance floor movers + addition - DMX problem

Hi Shane-



My guess is it's a cabling issue. Ditch the mic cables and get some CAT5 (it's cheap), put connectors on it, and replace the mic cables.



Also, any wire that meets the AES/EBU digital audio standard will work, too.
 
Re: Club install dance floor movers + addition - DMX problem

( I'm not a fan of mixing cables and only use a quality DMX cables.)

Have you tested and verified continuity and correct pinout?

Have you changed sequences of devices ( adjusting for addressing ) to see if problem floats?
 
Re: Club install dance floor movers + addition - DMX problem

Some machines prefer no termination, dont know about T-Beams & Trackspots but since they are from the same manufacturer they should get along nice.



Ditch the mic cable and test all the wiring wiring until you find the glitch.



In a pinch get a dmx opto-isolator and separate the 2 lines.
 
Re: Club install dance floor movers + addition - DMX problem

UPDATE - So I went into the club, took the trackspots down ( I was moving them anyway), and set them all on deck. Jumped them with short 15' mic cables, and fed the first one with a 25' mic cable from the light jockey dongle. All the lights freaked out. Removed them all but the one fed by the 25'cable and it was all good -I tried all of them as a single and any one trackspot would work. SO I tried adding just one more, and they would freak out. I added one more with a dmx cable, success. I had brought 600' of DMX line with me to make custom length cables anyway, so that is what I did. Everything up in the air, all patched in and ........Ghosting, still. I terminated, and it helped but they still ''stutter''... There is still one more 50' mic cable (the one through the ceiling) that hits the first fixture. So when things warm up around here, I'll be running a dmx feed line instead of that mic line. I also found that the minimac that was in between the pairs of t beams was not passing pin 1 through it's DMX through jack, so it came down, and out of the line...
 
Re: Club install dance floor movers + addition - DMX problem

Shane Presley wrote on Wed said:
UPDATE - So I went into the club, took the trackspots down ( I was moving them anyway), and set them all on deck. Jumped them with short 15' mic cables, and fed the first one with a 25' mic cable from the light jockey dongle. All the lights freaked out. Removed them all but the one fed by the 25'cable and it was all good -I tried all of them as a single and any one trackspot would work. SO I tried adding just one more, and they would freak out. I added one more with a dmx cable, success. I had brought 600' of DMX line with me to make custom length cables anyway, so that is what I did. Everything up in the air, all patched in and ........Ghosting, still. I terminated, and it helped but they still ''stutter''... There is still one more 50' mic cable (the one through the ceiling) that hits the first fixture. So when things warm up around here, I'll be running a dmx feed line instead of that mic line. I also found that the minimac that was in between the pairs of t beams was not passing pin 1 through it's DMX through jack, so it came down, and out of the line...
Click to expand...

I forget if you mentioned if before but you do have a terminator on the line at the end, right?

 
Re: Club install dance floor movers + addition - DMX problem

Shane Presley said:
Yep - I had to Rob, they were really freaking out before that, with termination, they move like they have a ''tick''....
Click to expand...

Even with "perfect" DMX wiring I've had problems like you describe using the lightjockey dongle. They all went away instantly using a DMX splitter box and running lines of similar fixtures each grouped onto their own output from the splitter.

Had some issues at one club where just inserting the DMX spltter -using only 1 output- and running the whole daisy chain unchanged fixed the problem. (Perhaps the LJ dongle has design issues that a simple buffer will cure?)

I use Swisson splitters (the phoenix plug bare-wire version makes installations quick ad easy) Elation ones work just as good too.
 
Re: Club install dance floor movers + addition - DMX problem

Xlr and dmx are shielded differently as well as xlr is 80 ohm and dmx is 120 ohm. First use good quality dmx on all your instruments. That will normally fix 90% of all problems. Second check that all dmx addresses on all lights are correct. An incorrect address on an instrument or an instrument that is in another mode can throw many other instruments in the line into unstable behavior. If that mic cable you have running through the ceiling is by any power lines in the ceiling that could also be your problem. Mic cable isnt properly shielded for the data packets sent across the cabling and power lines could be causing interference if the mic cable is crossing them. So again don't use mic cable. Lastly adding a splitter may also help to make super long cable runs shorter as well helping to keep a clean signal. And others have commented on terminator plugs.
 
Re: Club install dance floor movers + addition - DMX problem

+1 on the dongle. I've had several issues over the years with the smaller PC dongles unless I used a splitter. Solved problems twice without changing out audio cables installed by earlier company.
 
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