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Author Topic: Stage Lights Flickering When Off  (Read 1094 times)

Adam Thilges

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Stage Lights Flickering When Off
« on: November 28, 2018, 09:42:01 am »

Hello there, new to this forum but I have run out of options for what I know so I wanted to reach out to experts. Our stage currently has 14 Chauvet ColorDash Par Quad 18 down lights along with some generic LED strips and LED bars and 10 front stage wash lights all being controlled by a Jands Vista S1. 10 of the stage lights are wireless and 4 are daisy chained into the LED bars - cannot remember the name of the LED bars but they are brand name. The issue we have been having for the longest time is that the 10 wireless stage lights are wanting to flicker during our message when they are at 0% intensity. This problem gets exceedingly worse when we reinstall our paging system for the kids area that is wireless. Has anyone ever heard of Wifi signals interfering with wireless DMX boxes and how would one go about changing or fixing that. Recently we installed the 4 wired stage lights and 1 started flickering as well but we suspect that is just a bad DMX cable. Any help would be great, thank you.
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Taylor Hall

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Re: Stage Lights Flickering When Off
« Reply #1 on: November 28, 2018, 11:06:52 am »

Yes, wifi and other wireless devices can totally interfere with these wireless DMX dongles. It sounds to me like you've already discovered the issue if introducing more wireless noise exacerbates the issue. What brand/model wireless DMX dongle are you using?

I would first try getting everything on a hardwired DMX signal, even if only temporary. This should verify whether it is an issue with your cabling or the wifi dongle. If the issue persists, start testing cables and swapping them out with others. Work from the beginning of your chain to the end.

If going permanently hardwired isn't an option, try getting your DMX transmitter as clear a path to the receiver as possible. Get it high up away from other electronics that may be interfering.

You've also listed a fair number of fixtures in use, are you using a DMX terminator at the end of your chains? They're cheap premade (and easy to make on your own) and good insurance for squashing weird bugs like this. You might benefit from getting an optical DMX splitter to isolate the signal going to each of your chains, you may have a fixture somewhere not passing through properly and introducing unwanted noise that other fixtures are picking up down the line.

Also, how are your addresses laid out in your DMX pool? Butting things up right next to each other can sometimes cause DMX commands to "bleed" into another channel which might be triggering unwanted behavior. I've seen this happen with fixtures that reserve higher channels for macro or reset functions. I try to use the lowest channel mode possible for this reason unless I need that extra functionality. You could also try re-ordering fixtures in your chain, try putting the LED bars after the stage lights and see if the flickering follows.

Lots of things to test, and most of them time consuming, unfortunately. Starting with physical cables is at least an easy first step, though. Circle back with your findings and hopefully we can get this figured out.
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Dave Garoutte

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Re: Stage Lights Flickering When Off
« Reply #2 on: November 28, 2018, 12:21:16 pm »

+1 on the terminators.  They can solve all sorts of weird behaviors.
If possible, try changing the wifi tx/rx channel.

I had some simple LEDs on a dimmer pack once, that would flash intermittently.
I had to add a bleed resistor to fix that, but ultimately purchased a dimmer designed for LEDs.
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Taylor Hall

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Re: Stage Lights Flickering When Off
« Reply #3 on: November 28, 2018, 01:19:20 pm »


I had some simple LEDs on a dimmer pack once, that would flash intermittently.
I had to add a bleed resistor to fix that, but ultimately purchased a dimmer designed for LEDs.
Yeah, it only takes one gig dealing with that crap before getting LED dimmer packs XD
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Adam Thilges

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Re: Stage Lights Flickering When Off
« Reply #4 on: November 28, 2018, 02:06:50 pm »

Yes, wifi and other wireless devices can totally interfere with these wireless DMX dongles. It sounds to me like you've already discovered the issue if introducing more wireless noise exacerbates the issue. What brand/model wireless DMX dongle are you using?

I will run to church today and check on that. They are way up above the stage, 35 feet in the air so it isn't easily accessible.

I would first try getting everything on a hardwired DMX signal, even if only temporary. This should verify whether it is an issue with your cabling or the wifi dongle. If the issue persists, start testing cables and swapping them out with others. Work from the beginning of your chain to the end.

That is the end goal but in the meantime I was trying to help them out and see if we could nail down what the issue was. It appears that it is probably the items operating on the WIFI. I know the paging system display was actually placed very close to the wireless light receivers in the air so I will look at relocating that temporarily.

If going permanently hardwired isn't an option, try getting your DMX transmitter as clear a path to the receiver as possible. Get it high up away from other electronics that may be interfering.

You've also listed a fair number of fixtures in use, are you using a DMX terminator at the end of your chains? They're cheap premade (and easy to make on your own) and good insurance for squashing weird bugs like this. You might benefit from getting an optical DMX splitter to isolate the signal going to each of your chains, you may have a fixture somewhere not passing through properly and introducing unwanted noise that other fixtures are picking up down the line.

Do you have a recommendation on how to do this or if there are any links on here that show how to do this?

Also, how are your addresses laid out in your DMX pool? Butting things up right next to each other can sometimes cause DMX commands to "bleed" into another channel which might be triggering unwanted behavior. I've seen this happen with fixtures that reserve higher channels for macro or reset functions. I try to use the lowest channel mode possible for this reason unless I need that extra functionality. You could also try re-ordering fixtures in your chain, try putting the LED bars after the stage lights and see if the flickering follows.

They are definitely butted right up against each other. This would be very hard to change and is it very hard to even access the lights way up above the stage.

Lots of things to test, and most of them time consuming, unfortunately. Starting with physical cables is at least an easy first step, though. Circle back with your findings and hopefully we can get this figured out.

I will be going in later and checking the cables for the wired lights and then will start working on the wireless ones. Thanks for the input!
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Taylor Hall

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Re: Stage Lights Flickering When Off
« Reply #5 on: November 28, 2018, 02:34:55 pm »

-snip-
DMX terminators are just a 3 pin (or 5-pin depending on the fixture make) male end with a resistor across two of the pins. A google search will show you which pins and what resistor to use. Otherwise Hosa premade terminators are only 5-6 bucks on amazon. Then just plug it into the DMX output on the last fixture in any given chain.
Also, sounds like they need to put a scissor lift in the budget :P
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Debbie Dunkley

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Re: Stage Lights Flickering When Off
« Reply #6 on: November 28, 2018, 02:48:19 pm »

One more thing to remember - your lights are not actually 'off'. If they were - as in unplugged, you would not see any activity. As long as they are plugged in and connected, regardless of whether they are at zero intensity or not, they are still 'on' and victim to any weird wifi interference or DMX problems.
Always check cables first - I have switched out some that appeared fine yet I would get flickering and unintended activity. Switched them out for new ones and no issues.
I do find wifi control of lights to be very finicky and unless I stay on top of making sure my cables are good, my fixtures are being transported safely etc, weird anomalies will crop up. That's just my experience.
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Scott Hofmann

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Re: Stage Lights Flickering When Off
« Reply #7 on: November 28, 2018, 06:02:51 pm »

Another important item to check is that the shield wire connected to Pin 1 of your DMX cables is NOT connected to the metal shell of the connector, only to Pin 1. I've seen many manufactured cables (especially mic cables that you shouldn't be using anyway) made this way. It can establish a ground loop and easily cause flickering problems and unusual behavior.
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Don T. Williams

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Re: Stage Lights Flickering When Off
« Reply #8 on: November 30, 2018, 12:35:39 pm »

One more possible problem.  Mixing different brands (even pro level gear) of DMX fixtures "daisy-chained" can sometimes cause the flicker problem even if you use terminators.  32 fixtures daisy-changed is usually the maximum suggested.  A DMX splitter with outputs to each type/and/or brand of fixture should fix this.  Try the other suggestions first.
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Debbie Dunkley

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Re: Stage Lights Flickering When Off
« Reply #9 on: November 30, 2018, 02:53:52 pm »

One more possible problem.  Mixing different brands (even pro level gear) of DMX fixtures "daisy-chained" can sometimes cause the flicker problem even if you use terminators.  32 fixtures daisy-changed is usually the maximum suggested.  A DMX splitter with outputs to each type/and/or brand of fixture should fix this.  Try the other suggestions first.

+1
Plus without a DMX splitter, any issues affecting one fixture regardless of cause, would affect some or all of those fixtures down the line. With a splitter, any potential anomalies are restricted to only the fixture(s) connected to that DMX output.  I use a splitter but I still daisy chain lamps on the same tripod for ease of connection. So each 'group' of lights are separate runs from the splitter in my case.
There is another benefit... I can take all my runs from my splitter placed centrally on stage instead of having to make runs everywhere from one lighting tree to the next, and the next, and so on keeping things neat and cabling as short as possible.
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Re: Stage Lights Flickering When Off
« Reply #9 on: November 30, 2018, 02:53:52 pm »


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