Dimmer Issues

[GoboMan]

I'm currently lighting a show at a small theatre. The play is not cue intensive at all...there are only 12 cues in two acts. I'm using 38 dimmers... 24 of those are on a Sensor 26-channel rack, and the other 12 on a Sensor 12-channel portable rack. In this show, it's lights up at top of act, lights down at end of act, and every single light in the plot are on constantly between 50% and 90%, depending on the fixture, which consist of Source Four Juniors, Source Four 36-degree, 8-inch Fresnels, and Altman 360Qs. I also have two incandescent cyc strip lights. Four of my dimmers have two instruments running off of them.

In the last couple of days, all of the lights will randomly dim and flicker very fast, but not at all the same time. Each fixture will randomly dim/flicker at a different level, but they all do it at the same time. The dim/flicker will last for about 3 seconds, and then all the lights will come back on to their set levels. Some flickers are worse than others. Sometimes they will dim slightly, and other times they will flicker out to near or at zero before coming back on.

I checked the Sensor racks and no error messages are being displayed. The red Sensor beacon is not flashing on either of the dimmer racks, and no circuits on any of the modules are tripped. The 26-channel rack is in an enclosed closet, but we have a ventilation fan that is constantly running to expel the heat.

What could possibly be going on here? DMX cable? Problem with the light board (ETC Element)? Dimmers overheating?

Any help would be appreciated. Thanks!

 

[Les]

I would check cleanliness first. I've had Sensors flicker due to overtemp conditions, but I can't remember if the beacon was also flashing. Either way, it's a good thing to check and probably the easiest. Then move on to cabling if you still have no luck.

 

[GoboMan]

I would check cleanliness first. I've had Sensors flicker due to overtemp conditions, but I can't remember if the beacon was also flashing. Either way, it's a good thing to check and probably the easiest. Then move on to cabling if you still have no luck.

Ok. So that would include filters on the access doors, ventilation fan, and individual modules, correct?

 

[GoboMan]

Just cleaned the filters. They were CAKED in dust and dirt. Apparently they haven't been touched in a long time. Hopefully this will fix the problem. I'll get back to you!

 

[Amiers]

Reseat your dmx cables, this happend to me a couple of days after our show closed. Also make sure your racks are terminated.

 

[Les]

Just cleaned the filters. They were CAKED in dust and dirt. Apparently they haven't been touched in a long time. Hopefully this will fix the problem. I'll get back to you!

Hopefully so! I would also remove the modules and vacuum/blow them out individually (observe LOTO). Sensor modules also have an area to blow through on the end (I believe through a heatsink). Don't forget to do that as well.

 

[DavidNorth]

Just cleaned the filters. They were CAKED in dust and dirt. Apparently they haven't been touched in a long time. Hopefully this will fix the problem. I'll get back to you!

You have likely found the primary issue, but as stated above, do also blow out the control and dimmer modules [after LOTO]. The install rack could have been having airflow issues due to the dirt in the filters. This will cause all the lights in the rack to flicker or do a steppy fade down and back up, if on an edge condition of airflow. The portable pack should be ok, unless the control module itself is very dirty. It would be good to double-check.

Later versions of software made an Airflow Error a sticky message so that we could record that it happened. The reason for this is that people would open the door to see what was happening, the airflow would be better instantly because the clogged filter is in the now open door, and therefore no more issue or error.

Let us know how you make out.

David

 

[JD]

Be aware that dirt and lack of airflow can do cumulative permanent damage. There is a good chance that once cleaned everything will operate correctly, but SSRs (Solid State Relays) which are the heart of the dimmer modules, age due to thermal stress. Enough hot to cool to hot cycles causes the devices to fail. It's hard to reduce the cycles as it is the nature of dimmers, but we can reduce the range of temperature the devices get stressed by and the best way to do that is to have maximum airflow. The less the thermal range is, the longer the device lasts.