Control/Dimming Strand C21

[urban79]

So this has been an on-going issue in our installation, but I've never talked about this problem here, and it seems to have stumped a lot of people, so here goes:

3 years ago (just as I was starting this job) we were in the middle of a major renovation (we still are, but that's another story) that replaced nearly everything outside of the rigging in our space. New lighting raceways, dimmers, fixtures, a new truss FOH, plus seating, sound equipment, the whole nine yards.

This particular problems comes with the dimmers. After a period of time, various circuits begin to randomly strobe, at a variety of rates. This has appeared at virtually all lighting positions, but seems to be concentrated FOH. It has also shown up in our house lighting. Originally this was thought to be a result of a lack of neutrals to the house light circuits, but that issue was supposedly corrected over the summer, and the problem with the houselights has not gone away completely.

As far as I know, new wiring was run to all of the lighting positions (but not the houselights). There is one full C21 rack, and another that's probably 2/3 full. I believe we have a mix at the moment of IGBT and Basic modules, but the Basics were put in to try and troubleshoot originally. What makes this even more difficult to diagnose is that resetting the dimmer circuits solves the problem for a period of time, ranging from several hours, to weeks or more. So swapping modules to try and follow the problem is nearly impossible.

I know our install company has been discussing this directly with Strand, and I've been pulling modules and sending them back for a while now. But anyone have any miraculous ideas that might explain it?

Thanks!

Chris

 

[Gern]

My very sporadic intermittent random channel flickering was just a bear to trace.
Turns out it was a bad port on a very old opti splitter.

 

[derekleffew]

Does the strobe / flicker / random flashing issue happen a)during a static look, b)while a cue is fading, or c)both? What exactly do you mean by "resetting the dimmer circuits" fixes the problem? d)Rebooting the rack's processor(s), or e)turning off then ON the dimmer module's circuit breaker? Does the processor report any errors when the symptoms occur?

Many will suspect issues of this type to be associated with rack cooling or airflow. Is the dimmer room kept at the right temperature? Are the filters clean? Fans running? It sounds like it's probably not the dimmer modules themselves, but a processor or control issue. Our other "go to" question: Are the DMX (if applicable) lines properly terminator, DMX -ed? f)What console, and g)have you tried changing (lowering) the DMX transmission speed?

As tedious/difficult as it may be, get yourself a logbook, and have all users of the venue document EVERY instance of misbehavior. Date, time, temperature, humidity, which circuit, what else was happening, how long the lights had been in use that day, and so on. This can help, over time, to sense patterns. And hopefully arrive at a correct diagnoses and treatment.

 

[urban79]

Does the strobe / flicker / random flashing issue happen a)during a static look, b)while a cue is fading, or c)both? What exactly do you mean by "resetting the dimmer circuits" fixes the problem? d)Rebooting the rack's processor(s), or e)turning off then ON the dimmer module's circuit breaker? Does the processor report any errors when the symptoms occur?

I've only ever seen it happen during a static look; doesn't mean it couldn't happen during a cue fade, I've just never noticed. Before a performance, we've taken to turning off and on each module's breaker. I've never been able to find an error on the processor; neither has our system tech.

Many will suspect issues of this type to be associated with rack cooling or airflow. Is the dimmer room kept at the right temperature? Are the filters clean? Fans running? It sounds like it's probably not the dimmer modules themselves, but a processor or control issue. Our other "go to" question: Are the DMX (if applicable) lines properly terminator, DMX -ed? f)What console, and g)have you tried changing (lowering) the DMX transmission speed?

I have never had an overtemp warning come on, but there is no cooling in the open-air room where the dimmer's are located. I haven't checked the filters recently, but this has been a problem since the racks were installed brand new, so it would pre-date them getting dirty... Fans are running, quite loudly as a matter of fact! As for DMX termination, it becomes much more tricky for me to answer - I did not install the system, but it was installed by a very well-respected company in this region. I have no reason to believe it's not terminated. There are only 2 DMX lines run - 1 to the dimmers and another to a pair of VL's in the truss.

The console is a Strand Palette, but it also happens with frequency via the architectural system - a Vision.net system. I have not tried lowering the transmission speed, but would that explain it happening without the board?

As tedious/difficult as it may be, get yourself a logbook, and have all users of the venue document EVERY instance of misbehavior. Date, time, temperature, humidity, which circuit, what else was happening, how long the lights had been in use that day, and so on. This can help, over time, to sense patterns. And hopefully arrive at a correct diagnoses and treatment.

This is one thing I have been trying to implement - although I haven't taken to keep atmospheric measurements... What has been tough to keep track of is how long lights have been on over time (I don't have sole use or control over the space - school auditorium)

 

[icewolf08]

Even well respected installers can make mistakes or fall victim to bum equipment. That being said, there is not need to place any blame for the issues.

I agree with Derek's assessment. It sounds to me like a signal problem or a processing problem. Since you have swapped dimmer modules, replaced them, even tried different types, the problem is probably not in the dimmer modules. Here is a list of questions/things to check:
• Has anyone metered the power feed to the dimmer racks? Is it within specification? Is it fluctuating? Is it sized appropriately?
• If you turn off or disconnect the Vision.Net system completely, does the problem persist?
• If your console and Vision.Net are connected to the dimmers via DMX, have you tested the lines for proper wiring and the actual data with a DMX tester?
• If your console and Vision.Net are connected via network, are all the network lines terminated properly and well? Is all your network hardware (switches, routers, WAPs, etc.) configured and functioning correctly?
• Have you tried new processors for the dimmer racks?
• Have you noticed if the issue seems to crop up at a time when other building systems like HVAC are running?
• Is there some mode or reporting feature or something set up on the dimmers that shouldn't be? (I can't think of any offhand that would cause this, but who knows?)

The only thing you said that points to something beyond a data/processing issue is that flipping the individual breakers on the dimmers seems to fix the issue.

If this has been an ongoing problem for three years and the installer has not been able to fix it, it is time to get a Strand factory tech out there to look at it. If all your attempts to fix the problem and any service calls that have been made are well documented I would call the installer and Strand and figure out how to get someone there to look at it. If the system has never performed correctly since installation than this is probably the best course of action. In the end it will be cheaper for your installer and Strand to get someone out there to fix the problem rather than continually replacing parts and crossing your fingers!

 

[urban79]

So far everyone's come up with ideas that I have suggested. I have been in contact with someone on the board here from the factory - as I get more info I'll try to update for anyone interested. Thanks!

Chris