Flickering/fluttering lights

mumike

Member
Joined
Dec 4, 2007
I hope someone can help, i am in a bad spot. most of our lights in our 700 seat auditorium have begun flickering. There seems to be no rhyme or reason. About 50 channels of the 100 we normally use flicker and their flickering, in some cases, affects other lights. We have 4 etc
L86 racks, each with 144 dimmers. I have tried turning power off to each rack and dimmers alternatley but the other racks are still affected. I have tried swapping the control cards, nothing changes, i have bypassed the architectural rack, still nothing changes. As of now we have about 50 working (non blinking) dimmers, i have not yet taken any dimmer modules out. by not using the "bad" dimmers i do not have any flickering. I am going to try taking out some dimmer modules to see if that changes anything, but i can't see how. Nothing new has been added or changed to the electrical in this building in a few years. We need about 200 channels in the next 5 days for soe big events here. PLEASE PLEASE HELP!!!!!
 

icewolf08

CBMod
CB Mods
Joined
Jan 11, 2007
Location
Lititz, PA
First off, welcome to the booth, after we get your issue solved, or while we work on it, you might want to head over to the new member forum and tell us about yourself, we hope you stick around!

On to your issues...

What controller or console are you using? Does the problem persist if your console is not on? It sounds like your problem amy lie in a bad data run or possibly corrupt DMX signal from your console. It would probably be helpful if you can give us as much detail on your system as you can, which will help us make better informed suggestions.
 

Dustincoc

Active Member
Joined
Sep 7, 2006
Location
Madrid, New York
How long ago was the system installed? Sounds like a wiring issue to me. We had a couple wires in the DMX hardwiring crossed at one of the wall panels when it was installed and it took over a year to figure out the cause. The flickering only happened occasionally though so we just blamed Tom(our ghost). If it's an older system and the lights shut off and turn back on at a slower level, like the board is controlling them, I'd check the temperature sensor in the rack(if it has one). In HS we had an old old colortran rack that the temp sensor was going bad/getting dirty in and it would sense that the rack was overheating and turn off random dimmers to cool off.
Of course if it's more than one rack affected the same, it's most likely not the dimmers, but rather somewhere in the control system.

This might be completely off base but have you checked for some type of effect running in the background that's causing the lights to flicker.

It could also be an Electrical issue with the dimmers power connection, something best left a professional electrician to check out.

To check if it's the boards channels or the dimmers affected, try soft patching all the dimmers into a channel that doesn't have a problem and see if they still flicker.

So it could be:
DMX wiring issue
Rack/dimmer problem
Electrical supply
or a board signal issue

If you have a spare board you could try swaping out the board and see if it's fixed, Then try running a DMX cable direct to the racks to check the DMX cabling. If it's neither of these, try swaping the dimmers around in the rack(Good to bad, bad to good) and see if the problem stays with the dimmer address or moves around with the dimmer modules.
 

derekleffew

Resident Curmudgeon
Senior Team
Premium Member
Joined
Aug 21, 2007
Location
Las Vegas, NV, USA
As these are L-86 racks, they had to be manufactured/installed between 1986-1994, approximately, (unless installed used). What I suspect is one of the SSR cubes has failed and is allowing control voltage to come into contact with line voltage. Turn on everything, at a level of 25% or so, then start by removing the "known flickering" dual dimmer modules one at a time. If flicking continues, replace the module and continue. Repeat 4x144 times (are you sure there are 4 racks of 144? Are these quad 1.2Kw dimmers? If flickering continues after removing and replacing all the known flickeringers, start with the non-flickeringers. If that doesn't work, it's time for an ETC Field Service visit, or other Authorized service. Did you say where you're located?
 

mumike

Member
Joined
Dec 4, 2007
First off, let me say, you guys are AMAZING. I haven't tried those steps yet, but i am going to. we are using an expression board, and also a snapshot box backstage, I bypassed the snapshot and it still happened, while the lights were flickering, i disconnected the DMX cable from the wall and it still happened, i have not yet tried bypassing the snapshot AND disconnecting the DMX. I am embarrased to say i do not know a whole lot about the systems, we kind of know w little about a lot, i work at a university and the performance center is not our main focus, just one of many. What i have done so that classes can be held there is turn off all of the breakers on the dimmers that are affected...I will go back and one by one remove the diommer modules to see if that works. I will be in touch with the results. AGAIN, thank you all
 

mumike

Member
Joined
Dec 4, 2007
I'm sorry, i was mistaken(it was latE) It is 144 per side(each side has 2 racks stacked)
 

Chaos is Born

Active Member
Joined
Jun 30, 2006
Location
Cincinnati, Oh
By any chance are you using fluorescent on any of your dim-able dimmers? like house lights?

This was a problem for our flickering lights when we had the issue. We just had overlooked where it was coming from.
 

avkid

Not a New User
Fight Leukemia
Joined
Feb 17, 2004
Location
Lakewood, NJ
By any chance are you using fluorescent on any of your dim-able dimmers? like house lights?
This was a problem for our flickering lights when we had the issue. We just had overlooked where it was coming from.
That must have been slightly embarrassing.:oops:
 

Chaos is Born

Active Member
Joined
Jun 30, 2006
Location
Cincinnati, Oh
That must have been slightly embarrassing.:oops:
Yeah... well it was a combination of that and our castle cards buttons not working with some other underlying problems... however it was the main problem... It had been that way since before i started so i hadn't even thought to check to see if that was the issue...
 

mumike

Member
Joined
Dec 4, 2007
I did not check that....we did do some more troubleshooting and i seem to have isolated it to 5 dimmer backs all in a row in the middle section of our 3rd rack. I tried swapping the control card for that rack and after i powered the dimmer rack up, more lights were fluttering. so i went back and pulled MORE dimmer modules and eventually the lights stopped fluttering(except for the problem dimmers) I am hoping it is that center section somehow, but it is frustrating to try troubleshooting when one thing causes it to regress and i have to get back to the non-fluttering stage to continue to trouble shoot. thanks for all your ideas
 

Lightingguy32

Active Member
Joined
May 2, 2006
Location
New York
Your realize those controller cards for the L86 racks are addressed for specific dimmers in each rack, and swapping them about will make the situation worse. I looked on the ETC knowledge base and the last time I checked, there are specfic locations for each card that has a specific address and controls specific dimmers. Other wise, I believe that it would be a bad SSR (or several in your case).
 

David Ashton

Well-Known Member
Joined
Sep 8, 2007
Location
perth W Australia
By and large flickering is caused by transients from one dimmer feeding through the cabling and triggering scr's in other dimmers.The solution is to filter out the output transients with a snubber capacitor usually .1 microfarads across the output or the same capacitor across the power input to the dimmer.Sometimes scr's can have a sensitive gate which will false trigger, so look for incoming noise on the dimmers which are flickering and see if particular dimmers are causing the flicker and the look at the snubber capacitors on those channels.This has been a common fault on older Strand and some Jands dimmers but is a potential problem in any wave chopping type dimmer.
 

mumike

Member
Joined
Dec 4, 2007
I ahve been able to narrow it down to the center section of my third dimmer rack. I need to swap out the control cards (the etc rep told me about the addressing). The problem is, i do not have a spare so i will ahve to limp along. I pulled the affected dimmers and even though i lost those channels, the fluttering throuout the rest of the dimmers seemms to have stopped....i will let you know when i know more, thank you all for your help....
 

Lightingguy32

Active Member
Joined
May 2, 2006
Location
New York
Are the controllers in your dimmer racks SCRs (silicone controlled rectifiers) or SSRs (solid state relays). If it is a SSR then see if you can locate the bad dimmer by bringing a fader between 5 to 20 % and you will see somewhere in that line the light on that dimmer will bump to full and fall back. Locate which controller card this dimmer belongs to and replace the controller card. As for the SCR, I am unsure, never had to worry about them.