Film-Tech Forum ARCHIVE: ETC Sensor 48 dimmer system, has erratic operation upon raising house lights.

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Posted by Michael Moore (Member # 3867) on 05-19-2007, 03:54 PM:

I have 3 ETC 48 Sensor dimmer racks, one for my auditorium lights, and two for my stage lights. When the lights have been dimmed for longer then about 15 min. and then raised, the lights will come on slowly and stay on for 15 seconds then abruptly go out, for about 3 to 4 seconds and then come right back on and stay on. As one can see it would be very annoying after sitting through a movie or a live performance and have this happen, people would get up and start to walk and then the lights just go out and then back on; (sometimes its disaster)!! I have dusted the Racks with My air compressor many times, I increased air flow to the dimmer rack room and the same problem still exists. I suspect there is a glitch in the DMX 512 signal, or there is a problem with the program in the computer. But I really have no clue. HELP! [Confused]

Posted by Mark Gulbrandsen (Member # 72) on 05-19-2007, 04:07 PM:

The ONLY way to get it fixed properly is to call your local ETC service person. These systems utilize complex computers in each dimmer rack as well as in each wall station and then you also have a light board. So he is the only one that can check the programming...etc. The only thing I can suggest is unplugging the DMX line fomr the light console in the booth asn then see how the wall stations work out. The only problem I know about thats a common problem is blown 4kw dimmer modules. That was always ETC's weak spot. With Strand equipment theor weak spot os poorly made wall stations.

Mark

Posted by Paul Mayer (Member # 355) on 05-19-2007, 07:00 PM:

Is this a recent change in behavior? I've had issues similar to this with ETC Expression and Obsession desks where someone ran 75 ohm cable instead of 50 ohm between the desk and its processor rack. The resulting reflections in the line caused occasional erratic behavior like this even though the DMX cable runs between the processor and the dimmer racks were fine.

I've seen similar symptoms also with Colortran Series 1000 and 3000 desks and their ENR Series dimmers. The temporary fix was to reset the data cards on the dimmer racks each time the problem came up - a royal pain since the racks were about 200' away from the desk in that installation. Ultimately I think that one was traced to some sort of bad DMX cable run between the booth and the dimmer racks. Was fun to watch though - the thing would program and load the playback handles with its own fairly elaborate chase sequences all by itself in the middle of a show. [Smile]

Posted by Michael Moore (Member # 3867) on 05-19-2007, 09:12 PM:

Well the system was installed in 2001 and we just started the having problem in the past year but the past six months has been the worst. We get very erratic operation when the exhaust fan motor belt brakes to the dimmer room. lights dim and come on and flicker like crazy and then the units shut down. The problem is; who ever designed the renovations of the building had no clue as to what he or she was doing. They installed the dimmers in a room that is 10 x 10 with two big 3 phase 500V panels and one huge 3 phase 500 V transformer that could heat a small house (no lie). It the exhaust fan breaks the room will get to 100F in about 2 min flat. The exhaust fan can keep the room at about 78F and runs 24/7. Since 2001 we are on our second motor.

I don't know; but since this problem just started to get worse in the past six, I'm wonder if it has something to do with the onboard computer modules in the dimmers themselves. I'm calling ETC on Monday about this as well. I'll keep you all posted .

Mike

Posted by Mark Gulbrandsen (Member # 72) on 05-20-2007, 08:18 AM:

quote: Michael Moore
They installed the dimmers in a room that is 10 x 10 with two big 3 phase 500V panels and one huge 3 phase 500 V transformer that could heat a small house (no lie). It the exhaust fan breaks the room will get to 100F in about 2 min flat. The exhaust fan can keep the room at about 78F and runs 24/7. Since 2001 we are on our second motor.

That room is otherwise known as an electrical vault and is the most common place for dimer racks to be installed, yes they get warm. A back up fan for when the main fan breaks down might be wise to install. Don't worry... the dimmer modules are individually thermally protected and the rack as a whole is also protected thermally by the rack computer. If you overheat is will go into safe mode. Have you determined if this problem is in the lighting board or in the wall stations(by disconnecting the board)yet? Its very inlikely the installer used the wrong DMX cable since these systems are factory inspected in that regard during the initial turn on procedure and programming. Weather yourt wall stations use the same cable or not I don't know... Both Strand and Colortran use multi-condictor cabling that is shielded for the wall stations.

If your wall control stations or rack computers are bad then retrofitting with Johnson Systems gear is your best route to reliability. I've done many rack retrofits with their rack computers and wall stations and they are by far the most stable and the very best available.

Mark

Posted by Michael Moore (Member # 3867) on 05-20-2007, 03:08 PM:

Still have the problem when the board is disconnected, so I guess it is a problem with the wall units. I check this morning and noticed that someone opened a panel in the room that vented warm air back into the room from the exhaust fan. I shut it and the temp went down considerably. Also notice that the Red indicator LED for the rack that has the house light dimmers was flashing. I reset the computer, and the lights worked well, but after about an hour I tried and got the same problem and this time with the board removed. I am going to blow them out again tonight looks like they are dusted up again. I'm calling ETC on monday like I said to clear this up.

Mike

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2007, 05:58 PM:

Don't your ETC racks have air filters on them? Both Strand and Colortran do.... They should be cleaned monthly if high use.

Mark

Posted by Michael Moore (Member # 3867) on 05-23-2007, 06:08 PM:

yes they have filters and they are cleaned about every two weeks but this is not my job; but it ends up being my job.

I figured out the problem with the help of Tech support, My ETC rack 3 is farthest away from the air intake, it overheats, no matter what I do. I am increasing the room ventilation with a larger exhaust fan. Once this is done I hope that it will fix the issue. ETC told me that it is most likely the room is too stuffed and needs to be vented more.

They have us on record for our install and noted that everything was inspected and all cables are correct.

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2007, 07:21 PM:

Is there an over temperature LED on the rack compuer... Or does the rack computer readout say its in an over-temp condition?

Mark

Posted by Michael Moore (Member # 3867) on 05-23-2007, 08:06 PM:

computer says its airflow problem, but the fan on top of the unit does not come on. ETC says it maybe a problem with the computer telling the fat to come on, or it maybe a bad fan relay on the board. The led blinks on the top of the unit when ever it has this problem.

Posted by Michael Moore (Member # 3867) on 05-26-2007, 03:43 PM:

Tech came out on Friday, Appartently the computer in dimmer rack 3 has a bad air flow sensor module. We were given a loaner for the time being until ours can be repaired.

Mike

Posted by Mark Gulbrandsen (Member # 72) on 05-26-2007, 10:16 PM:

That is one thing in Strand dimers that gives little trouble. I don't know what type of airflow sensor ETC uses but it must be very dust sensitive. You may also want to consider filtering the air entering that room... assuing the room is sealed fairly well.

Mark

Posted by Michael Moore (Member # 3867) on 05-26-2007, 10:39 PM:

I have a filter on the intake but it clogs too fast and really cuts down on air flow to the room. I'm not sure why it is malfunctioning and the tech was unsure as well, he just says stuff breaks. But he did comment that the doors must be kept closed with the filters in. We have this sound/lighting tech who comes in for lives shows and his fix is to take the doors and prop them open thinking that the air will get the racks better but he is really making them more dusty!

Mike