Why are my lights flickering?

[microstar]

If you tape some plain ol' wax paper in front of them, it will even out the hot spots and diffuse the beam a little.

 

[Stevens R. Miller]

If you tape some plain ol' wax paper in front of them, it will even out the hot spots and diffuse the beam a little.

That sounds like a promising idea. I'll try it. Anything else that would widen the beam with less loss of light? Some sort of plastic negative fresnel lens maybe?

 

[BillConnerFASTC]

I would assume the selador lenses that ETC supplies for a number of fixtures would do that.

 

[Crisp image]

@Stevens R. Miller @TimMc You can probably get away with "I'm too old for this excrement!" and / or "Equine excrement" in lieu of BS. And then there're always my old standbys "Phuque!" and "Phucough!" Poor SpellCheck doesn't have a clue.
Toodleoo!
Ron Hebbard.

@RonHebbard Wouldn't that be bovine not equine? Although equine works just as well.

 

[microstar]

That sounds like a promising idea. I'll try it. Anything else that would widen the beam with less loss of light? Some sort of plastic negative fresnel lens maybe?

You really want Light Shaping Filter from Elation:
http://www.elationlighting.com/lsf-filters

Pricey at $100 per 20" x 24" sheet but it does work. You don't get near the beam spread they are advertising, but still very useful and doesn't cut the brightness as much as other solutions.

 

[RonHebbard]

@RonHebbard Wouldn't that be bovine not equine? Although equine works just as well.

@Crisp image You Sir are most definitely correct. You've got your horse excrement and then you've got your bull excrement. Most days we've no shortage of either. Horses for courses and bulls for balls. Select your flavor but PLEASE do so with decorum and finesse.
Toodleoo!
Ron Hebbard.

 

[JohnD]

@Crisp image PLEASE do so with decorum and finesse.
Toodleoo!
Ron Hebbard.

Panache Ron, you forgot Panache, and I don't mean in the historical "stick a plume of feathers in it" sense.

 

[EdSavoie]

DMX data too: 0" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch">

I could do that, but I'd probably be lying to you. It does have vents in the back and there's a fair amount of space behind the dimmers and the back of the cabinet. The whole thing is years old. If it were going to fail (or, God forbid, ignite) for lack of cooling, it would have done it a long time ago. I do wish they'd installed the whole thing in the hallway, not just off stage, though. It's obnoxious to have to listen to the fan blowing through a whole show.

Before I comment on what I think might be happening, fan noise on the dimmer reminds me of our CD80 rack, where the dying fans have yet to be replaced (Our work order system has a nasty habit of taking forever with theatre related issues) the squeaking noise is very audible from it's position in the electrical room stage right of the house, really obnoxious when the room falls silent.

Anyways... With what you've mentioned as for symptoms, i'm wondering if the problem is indeed something to do with the processor or the control bus going to the dimmer modules. I'm reminded of a few different things. First off, I've seen older [autolink]processor[/autolink] based electronics go wonky as described after warming up. (Speaking in terms of both time turned on and heat) It also reminds me of my experiments controlling intelligent [autolink]LED[/autolink] strips, I noticed the control signal getting "sloppy" and falsely triggering LEDs other than the one specified, with random colours. This only happened when active data was being sent, as in lights turned on. I could limit the [autolink]effect[/autolink] by reseating connections, and making sure there was as little resistance as possible between (digital) grounds.

Even if heat isn't enough to make something die outright or spectacularly, it can most certainly slowly bake systems to death. I've seen (mostly computers) bake themselves in such a way where they would crash or become unstable only after having been on for some time.

This is of course all speculation. Someone with much, much more experience than I could probably comment moire accurately...

EDIT: Blast my 1:22 AM Control booth posting, I somehow missed two full pages of much more informative posts...

 

[EdSavoie]

They do produce the saturated colors that I have noticed are characteristic of LEDs.

Call me a new-age millennial if you must, but I absolutely *adore* the look of saturated blues.

In reference to kickstands, silhouetting from the front with very saturated hues by using them as footlights, while having lights up top washing the stage in a contrasting colour makes for a really nice effect.

It's even more fun when you accomplish the same with a small army of BLB tubes, our "Addams Family" production did a complete number ("The moon and me" for anyone following from home) almost exclusively front lit by clothing fluorescing

(Sorry attached image is of poor quality, it's from a very last minute and not really calibrated camera that was used at the time.)

 

[RonHebbard]

[QUOTE="...it looked like a disco did in my college days (late '70s).

...We noticed that whenever a light flickered, its LEDs also flickered on its dimmer. We also noticed that, if all lights were off, there was no flicker. This was true when the computer was connected and streaming DMX data too: if even one light was up, others would flicker

...The problem stayed with the slot the dimmer goes in, not with the dimmer. We concluded, therefore, that something upstream of the dimmer and downstream of the computer input

Before I comment on what I think might be happening, fan noise on the dimmer reminds me of our CD80 rack, where the dying fans have yet to be replaced (Our work order system has a nasty habit of taking forever with theatre related issues) the squeaking noise is very audible from it's position in the electrical room stage right of the house, really obnoxious when the room falls silent.

Anyways... With what you've mentioned as for symptoms, i'm wondering if the problem is indeed something to do with the processor or the control bus going to the dimmer modules. I'm reminded of a few different things. First off, I've seen older processor based electronics go wonky as described after warming up. (Speaking in terms of both time turned on and heat) It also reminds me of my experiments controlling intelligent LED strips, I noticed the control signal getting "sloppy" and falsely triggering LEDs other than the one specified, with random colours. This only happened when active data was being sent, as in lights turned on. I could limit the effect by reseating connections, and making sure there was as little resistance as possible between (digital) grounds.

Even if heat isn't enough to make something die outright or spectacularly, it can most certainly slowly bake systems to death. I've seen (mostly computers) bake themselves in such a way where they would crash or become unstable only after having been on for some time.

This is of course all speculation. Someone with much, much more experience than I could probably comment moire accurately...

EDIT: Blast my 1:22 AM Control booth posting, I somehow missed two full pages of much more informative posts...[/QUOTE]
@EdSavoie LOVED IT! I recognized your quote "...it looked like a disco did in my college days (late '70s)" the moment I read it whereupon I just HAD to read back to find the post you'd quoted from. Count on my young countryman to tag this meandering four page thread ALL THE WAY back to the OP's original post. Trust me on this @EdSavoie , you belong here. You fit in just fine even if you spell colour with a 'U'. Odd, our American buddies spell four with a 'U' and think nothing of it.
Thanks for visiting Master Ed and doing your best to drag us all back on course. ['Course' There's another of those words with 'U's we share in common.]
Don't forget to set your clocks back in about 11 minutes. [ Where are the instructions for my sand filled hour glass?]
EDIT: Clearly the blind old geezer's botched his quotes again.
Toodleoo!
Ron Hebbard.

 

[EdSavoie]

I'm not blind yet I still managed to botch the quote...

 

[RonHebbard]

I'm not blind yet I still managed to botch the quote...

@EdSavoie See! I told you you fit in here and you're already an over-achiever at 18.
Toodleoo!
Ron Hebbard.

 

[Jim allen]

Well, yet another middle school is throwing curve balls at me. This one's system is based on a Lehigh DX2 with a rack control system (picture below) and a small architectural control processor with four faders (a master and three that each control a part of the house). The ACP has a Doug Fleenor Designs PRE10-A DMX512 10-Zone Wall Controller with ten presets and and an LED that indicates that it is passing DMX data through it (at which time it gives up control).

We plug our computer into the ACP (we're running QLC+ and using an Enttec OpenDMX), and things work as expected. But last night, we noticed one of the lights flickering. I thought it was arcing, but then we saw that others were doing it. As the evening wore on, it got worse, to the point where it looked like a disco did in my college days (late '70s). We thought maybe the computer was the problem, so we disconnected it. The ACP includes an "all on" preset, and a few others, including an "apron only" preset. When we activated "apron only," we again saw lights that should have been off flashing on and off. By "on and off," I mean a very brief "on" time, followed by anywhere from half a second to several seconds of "off" time. This is with no computer connected.

We cycled the power on the rack and the problem seemed to go away, but returned after a few minutes. Three of us were working on this and all agree that it seemed to follow the same progression each time we cycled the power: the problem went away, then returned after a few minutes, gradually growing worse. I will admit, however, that this observation is more anecdote than science. What is certain is that the problem always returned.

At the rack, each dimmer is in a module paired with another. Each has two green LEDs on it, labeled "A" and "B." We noticed that whenever a light flickered, its LEDs also flickered on its dimmer. We also noticed that, if all lights were off, there was no flicker. This was true when the computer was connected and streaming DMX data too: if even one light was up, others would flicker, but nothing flickered if we set the scene to total blackout.

We tried swapping dimmers that were flickering with others that weren't. The problem stayed with the slot the dimmer goes in, not with the dimmer. We concluded, therefore, that something upstream of the dimmer and downstream of the computer input, was sending sporadic signals of some kind. This would imply that most likely the culprit is either the ACP, or the rack module. We looked inside the rack to see if there was a DMX input downstream of the ACP, but what we found was not a five- or three-pin plug (there's actually just a terminal strip in there that the ACP apparently feeds into), so we couldn't connect downstream of the ACP.

Of course the school has put in a work order for service, but our show is supposed to open on Friday, so I am not optimistic that the contractor will visit before then, much less fix the problem. But we are stumped!

Any suggestions?

View attachment 15468

I had the same problem with one of my ETC Sensor racks and it was the CEM module. Does your have one?? Don't know Leigh systems.

 

[Stevens R. Miller]

I had the same problem with one of my ETC Sensor racks and it was the CEM module. Does your have one?? Don't know Leigh systems.

What's a CEM module?

 

[kenact]

My crummy Chinese lights just showed up. I'll give them a spin and report back here.

View attachment 15498

Just my own experience with "crummy Chinese lights".

I bought some cheap RGB/LED Par Cans. I've used them on a number of shows, but not without issues. When one of the instruments exhibited power problems at the plug, I discovered that the wire in the power cord was about as thin as the wire in my ear buds. I also discovered that, although they had a 3 wire plug, only 2 wires were connect.

Another issue I had with one instrument, green and blue were reversed.

In one production, my RGB/LEDs were extended from an older 12 channel, 2.4K dimmer pack, and just before our performance was due to begin, ALL the lights started flashing in what appeared to be a random order. I tried adding a terminator to the end of my DMX chain, to no affect. When I disconnected my RGB/LED chain, the flashing stopped. I found that one of my RGB/LEDs was causing the problem, removed it from the chain and ran the show.

I'm not too upset, because they were cheap, in the same price range as yours.

 

[sk8rsdad]

What's a CEM module?

It is the brain for a Sensor rack. It's basic function is to translate control protocols into firing signals for the dimmer modules.

 

[derekleffew]

What's a CEM module?

I don't know if that was rhetorical or sarcastic or other, but, from https://www.controlbooth.com/threads/cem.9026/ :

Control Electronics Module. A term for the ETC Sensor (and applied generically to other manufacturers') dimmer's "brain." The module on a dimmer pack or rack where various parameters are set. This will always include the pack's/rack's starting DMX512 address, and may include features such as voltage regulation, dimmer curves, implementation of secondary DMX or analog signals, etc. Prior to the Sensor's introduction in 1992, this item was often referred to as the "control card" or "control module."

I believe your Lehigh DX2 dimmer rack calls it the System Control Module. (Gotta love those TLA s, right?)

 

[carmellights]

DMX data too: 0" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch">

Well, yet another middle school is throwing curve balls at me. This one's system is based on a Lehigh DX2 with a rack control system (picture below) and a small architectural control processor with four faders (a master and three that each control a part of the house). The ACP has a Doug Fleenor Designs PRE10-A DMX512 10-Zone Wall Controller with ten presets and and an LED that indicates that it is passing DMX data through it (at which time it gives up control).

We plug our computer into the ACP (we're running QLC+ and using an Enttec OpenDMX), and things work as expected. But last night, we noticed one of the lights flickering. I thought it was arcing, but then we saw that others were doing it. As the evening wore on, it got worse, to the point where it looked like a disco did in my college days (late '70s). We thought maybe the computer was the problem, so we disconnected it. The ACP includes an "all on" preset, and a few others, including an "apron only" preset. When we activated "apron only," we again saw lights that should have been off flashing on and off. By "on and off," I mean a very brief "on" time, followed by anywhere from half a second to several seconds of "off" time. This is with no computer connected.

We cycled the power on the rack and the problem seemed to go away, but returned after a few minutes. Three of us were working on this and all agree that it seemed to follow the same progression each time we cycled the power: the problem went away, then returned after a few minutes, gradually growing worse. I will admit, however, that this observation is more anecdote than science. What is certain is that the problem always returned.

At the rack, each dimmer is in a module paired with another. Each has two green LEDs on it, labeled "A" and "B." We noticed that whenever a light flickered, its LEDs also flickered on its dimmer. We also noticed that, if all lights were off, there was no flicker. This was true when the computer was connected and streaming DMX data too: if even one light was up, others would flicker, but nothing flickered if we set the scene to total blackout.

We tried swapping dimmers that were flickering with others that weren't. The problem stayed with the slot the dimmer goes in, not with the dimmer. We concluded, therefore, that something upstream of the dimmer and downstream of the computer input, was sending sporadic signals of some kind. This would imply that most likely the culprit is either the ACP, or the rack module. We looked inside the rack to see if there was a DMX input downstream of the ACP, but what we found was not a five- or three-pin plug (there's actually just a terminal strip in there that the ACP apparently feeds into), so we couldn't connect downstream of the ACP.

Of course the school has put in a work order for service, but our show is supposed to open on Friday, so I am not optimistic that the contractor will visit before then, much less fix the problem. But we are stumped!

Any suggestions?

View attachment 15468

i might suggest that this is a DMX issue. couple of approaches i would take to troubleshooting this would be :

1 see if you can trace the flickering consistantly to certain circuits. write down those circuit numbers

2 at the rack, you will either have a three phase power feed or a single phase - cant remember how Lehigh devides the rack by phase, but if you contact lehigh, you can find out. the system can fail in predictable patterns at the control electronics, that is why knowing the specific circuit numbers ( patched one to one ) can tell you where they are physically in the rack, and if that is phase related, and therefor if the failure at the conctrol module is phase related.

3 - it sounds like you have several different brands of DMX devices in the system. there can be timing and parity differences betweek the devices that will cause random flickers. I would review a few basic DMX rules and see if you are violating any of them. termination is a good place to start, non specified data cable is another. start simple. divide and conquer as my friend Milton davis says. establish DMX port output 1 directly to the wall outlet - uplug every other DMX device, get it out of line. cook the system at various levels for an hour or so - or even worse write a looping chase cue nice and slow at about 65 % for the on and a fade time of 5 seconds. let that cook for a few minutes - this will irritate the system, and you should see the flickering.

4 if it works with no flicker doing step 3 then begin adding the devices back one ata time. you should find a device like a splitter or a specific cable that when added makes it flicker.

5 - call legigh. they will help a lot. describe your system layout clearly, have model numbers and mfg. names available. draw a system riser if possible, that helps them a lot.

i would ask if there are [autolink]LED[/autolink] or movers inthe rig. and ask if the [autolink]system[/autolink] had flickered before ? what did you ( or that elusive Mr. nobody ) change or add to the [autolink]system[/autolink] ?

thoughts ?

 

[Stevens R. Miller]

What's a CEM module?

I don't know if that was rhetorical or sarcastic or other...

It was other, where "other" is "ignorance." I really just didn't know.

 

[Stevens R. Miller]

Before I comment on what I think might be happening...

(quite a detailed list of good ideas elided)

thoughts ?

Well, I dearly wish I had the time and unlimited access needed to pursue this as you and others have suggested. As an amateur techie in a community theater company that is only grudgingly tolerated in our public schools, I can only do so much.

The outside vendor that supports the school here is "Artistic Concepts Group." They sent a technician yesterday, fellow named Ryan, and I was lucky enough to be there when he arrived (where "lucky enough" was that I took my computer and camped out in the auditorim as soon as the school opened for election day). Ryan was unusually knowledgeable and also very patient. Alas, as is typical of comes-and-goes problems when the actual expert is on hand, the flickering did not recur, even after we reconnected the ACP. Ryan hung out for about an hour as we tried this and that, to no avail. During that time, he told me a number of interesting war stories regarding similar problems, many of which he said ended up being induced by unrelated equipment (like HVAC systems, and so on).

What this means to me is that I just can't fix this myself. If it comes back, I'll call ACG and ask them to send Ryan again and right away. Other than that, I think this one is just out of my league.