Anyone ever run into this? LEDs/DMX burst... Flourescent EMF?

Okay, I don't even know where to begin to describe this problem or even if this is the right thread to post in, but basically we have an Express 48/96 console on a Net2 system (three 4-port nodes, and two 2-port nodes). Everything was working fine throughout tech a week ago, then one day I came in and the LED's that are plugged into the nodes were randomly bursting (ie a channel blitzes on for a milisecond, say reds from SL box boom, then maybe 10 seconds nothing, and a burst from the SL dance boom, green, then maybe 30 seconds nothing, and a whole other set will burst). It has gotten to the point of flashing all over the place, like a rock show, at times, but more often there is lag time between the bursts.

Now, the oddest part is that there are times when the theatre is dark, nothing is on, just power to these errant LED's and nodes..... and everything is calm, no bursting. When we switch on the flourescent worklights, the LEDS then started to burst, turn off the works, and they settle down and can go minutes with nothing. 

We have tried, maybe too many things to list, trying to figure out this possible correlation. The thing is that the LED's had also done this during shows, when the work lights were off. 

The one thing is that when the console was plugged at the tech table in the house we had no problems. It really only started when it got moved back to the booth, and the LED's were left on overnight. 

We've since discovered that the DMX line from the booth seems to run to the back of the theatre in the rack, then ties into to the DMX that goes to the mid-house and back. 

The DMX from SR isn't even connected (is this really an ETC approved job?)

So, we've disconnected the mid-house DMX from the system thinking that the DMX run back and forth was too long and degrading the signal. It's seems to be better, though every so often one of the LED's gives a little "shout". 

The questions in all of this foremost are; would the fluorescent works light really be interfering with the DMX, is it EMF causing such interference? And how on earth does this DMX tying together make sense (shouldn't each of the three DMX lines come to the block in the rack and then gone into the 4-port rack node? Only one line goes to the node), and how did this installer get certified by ETC ----> A SR DMX line that wasn't ever connected to anything in the terminal block (D2), and we have a "LS Power" duplex circuit on our catwalk that has the Cat5 line, but there isn't even cable run to the outlet box (some random 16 guage wires we don't know what for though!).

Any ideas on how to troubleshoot this further would be much appreciated! (We have slowed down the DMX on the ports and at the console)

Couple of photos for reference....







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  • Problem seems to have been resolved!!!

    Get this..... installers never ran a ground wire for the rack node. When we grounded, the flicker isn't replicated. When we disconnect the ground the problem starts.
    (It's only been 15+ years!).
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