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DMX/ Noise interference? 


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I've got some DTS bricks that flash out of their normal state erratically into  purple throughout performances. Still gathering information on how regular, but it does seem to occur with loud noises (but not every loud noise)- Only a couple times and slips back into it's programmed state. I've checked all the DMX cables to make sure they've not been a snack for a squirrel, but all looks to be in order. Has anyone had a similar issue with these or any similar lights? 

Thank you!

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Do the devices have a sound to light function? If so it may be triggering. I can switch some of mine into sound to light mode with an appropriate DMX signal. 

If they do have sound to light, find the microphone and cover it with a pad of something to absorb the sound. See if the problem goes away. However it will not help if vibration is coming up through the fixture mechanically, in which case try to decouple it from whatever is vibrating. 


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Just had a quick search of the manual and there's no mention of "sound" or "audio" anywhere. Moreover the fixture does support setting things via RDM so it's clearly not the same issue as described in that other thread that I linked to. Sorry about the red herring. What desk are you using?

Edit: Also, what other fixtures have you got on that DMX line and is it terminated correctly?

Edited by DrV
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Broken cable can do this kind of thing. DMX (like most digital protocols) tends to keep working reasonably well under absolutely terrible conditions - until it suddenly doesn't.

DMX is perhaps worse than most, because there's no error checking and error correction is entirely based on the idea that a new packet will be along in a few milliseconds to correct a wrong value. That worked very well with tungsten lamps and (to some extent) moving lights because they simply can't physically react that fast - but LEDs can.

Making sure your cables are correctly terminated both prevents a lot of issues and - perhaps more importantly - causes a semi-broken line to stop working altogether, instead of intermittently doing crazy things. Much easier to find and fix the problem.

I've seen many sites where one of the wires had broken and was making intermittent connection. It'd usually appear to be just fine, then occasionally cause all kinds of weird flicker - sometimes apparently triggered by loud sounds, possibly because the noise would make the broken strands vibrate.

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