Control/Dimming Dimmer pack problems (Leviton D4DMX-MD3)

[Pyrotech]

Hi everyone,

I did some searching in the Lighting section, but didn’t see anything on this issue.

I’m a volunteer with a small church/community theater group. I started out helping with special effects (since I have a pyrotechnician license) and general electrical (since I worked for the local power company). As other individuals have moved out of the area, I have inherited the position of technical director (with little background beyond having performed some grunt work on sound and lights for the previous technical director).

After our last production, the church removed the carpet in the Fellowship Hall (where the stage is located) and had the slab sanded to make a polished concrete surface, which generated a large amount of dust.

When our new director started a kids summer theater camp, I discovered an issue with one of the dimmer packs (out of four). It would bring up the lights as the fader was increased, but then stay at whatever the highest point was and not decrease when the fader was zeroed. Turning the breaker to the outlet off would kill the lights, but the next try would have the same issue. I tried all the recommendations I could find, including the stereotypical tech support “turn it off and back on”, zeroing out the channel, clearing the show and finally doing a full reset on the board.

Our lighting board is an ETC Express 48/96 and the lights are a mixture of incandescent and LED fixtures.

I bought two new dimmer packs (Leviton D4DMX-MD3) and replaced the malfunctioning one and another one that was working, but occasionally blinked the lights on its channels.

For a few weeks, both worked perfectly. At a rehearsal last week, one of the lights on the dimmer pack in the location that previously wouldn’t turn down was on when I entered the auditorium – while the channel fader and master slider were off – and nothing would turn the light off (or the others on that pack on), including all of the previously mentioned solutions again. Using the breaker in the electrical panel finally got the light off, but now nothing on that pack works at all.

Other lights plugged into that outlet still work.

Any ideas that don’t immediately involve accessing the dimmer pack itself? (see picture of ladder…at 65, I prefer to minimize the number of times I climb it, not to mention it takes three people to put it up).

PS, I took the cover off the old dimmer pack and found almost no dust inside despite the floor sanding and the fact that it had been in place for several years prior to the sanding. Or any parts that would seem to be bothered by dust.

Thanks.

Jay

 

[Mac Hosehead]

I have used these dimmer packs before and have not seen the issues you have described. However, when I hear of lights blinking and channels not responding correctly to the console output, I have to think that the DMX signal might be compromised. Do you have a terminator at the end of the run?

There is also a DMX speed setting on the Express that you can try but I am doubtful it will affect anything.

Nice ladder.

 

[Amiers]

Sounds like bad cable somewhere. Since you replaced the pack. Ghosting fixtures can also be a power issue as well as dmx ghosting from the console itself. Turning the console off then on should reset the dmx signal. If that’s not doing it then I would swap out your dmx. Make sure they are proper DMX cables and not mic cables.

 

[Pyrotech]

...when I hear of lights blinking and channels not responding correctly to the console output, I have to think that the DMX signal might be compromised. Do you have a terminator at the end of the run?

There is also a DMX speed setting on the Express that you can try but I am doubtful it will affect anything.

Nice ladder.

There is a terminator at the end of the run. I will check the board for what the DMX speed is - although after the number of times I have reset it, I assume it should be at the factory default.

Thanks for the ideas.

It *is* a nice ladder. It has more flex than I care for from about 1/3 of the way up until near the top, especially when you're climbing with gear in your hands. Sadly, we had an opportunity to buy a used scissor lift that our maintenance guy said needed very little work for not a whole lot more than the ladder cost. But a couple members of the church council (who don't have to work on the equipment in the auditorium or sanctuary at that height) were worried about future maintenance on it and voted it down in favor of the ladder...

Life goes on

 

[Pyrotech]

Sounds like bad cable somewhere. Since you replaced the pack. Ghosting fixtures can also be a power issue as well as dmx ghosting from the console itself. Turning the console off then on should reset the dmx signal. If that’s not doing it then I would swap out your dmx. Make sure they are proper DMX cables and not mic cables.

Thanks. To the best of my knowledge DMX specific cable was used when the lights were put up originally and as additional lights were added. I did find when working on it for our last show that much of the cords and cables were fastened to the support bar with zip ties. As I've worked on sections, I've cut them off and replaced them with Velcro wrap. I think there is a cable tester in the back room, I suppose it's possible a zip tie was fastened tight enough to damage a cable.

 

[microstar]

Agree with @Mac Hosehead and @Amiers that it is probably a DMX/cable issue. as the Express consoles are almost bulletproof in my experience. Per above, you might want to select the lowest DMX speed as there is
a menu item for that. I would use a VOM or cable tester to make sure Pin 1 goes to Pin 1, etc. and MOST IMPORTANTLY, Pin 1 does not go to the connector shell as this could cause a ground loop and strange
DMX behavior exactly like what you are experiencing.
If you happen to be using microphone cable, I would replace it with DMX cable and use a terminator at the end of your DMX chain.

 

[ACTSTech]

Stupid question but how’s the power flowing in? If it’s not clean coming in or jumps around it can cause dimmer issues, but that’s a guess. Is there a way (too much work, I know) you can take a rack somewhere else to test?

A Furman power conditioning unit worked for me one time with a goofy sound system. Our issue was the line into the building. Once the HVAC kicked on, even though the panels were separated, the voltage drop made my sound board crash.

 

[Pyrotech]

Stupid question but how’s the power flowing in? If it’s not clean coming in or jumps around it can cause dimmer issues, but that’s a guess. Is there a way (too much work, I know) you can take a rack somewhere else to test?

A Furman power conditioning unit worked for me one time with a goofy sound system. Our issue was the line into the building. Once the HVAC kicked on, even though the panels were separated, the voltage drop made my sound board crash.

As an ex-power company employee, possible power quality problems did occur to me. We're in town and relatively close to a substation, so it shouldn't be low voltage. It's possible there have been voltage surges or other disruptions, but none of the computers in the building have had issues - and an identical dimmer pack an outlet over is working OK, but I know that's not definitive either.

The main heat is gas, but they've been installing a number of ductless heat pumps, so perhaps they are generating some harmonics, voltage drops or some other type of fluctuation.

If the cables don't show any problems and resetting the DMX speed doesn't solve it, I'll talk to some my engineering coworkers (well, former, but I haven't been retired so long they don't remember me) and see if we can schedule their power quality monitor for a while.

Thanks

 

[Pyrotech]

UPDATE

It's been longer than I thought, but there was a delay for the production date, scheduling conflicts, the holidays, etc.

Anyway, the dimmer pack/lights are now working again! Thanks to everyone for your ideas. I can't say for sure what solved the issue as I did multiple suggestions at the same time to minimize the number of trips up and down the ladder. I replaced all the DMX cables from the previous dimmer pack (which has never had any problems) to this dimmer pack with new cables. I did find one cable that still had an extremely tight zip tie on it!

I also noticed the display on the pack wasn't lit. At first I assumed this was a feature, having the display shut down after the unit is programmed to avoid extraneous light and/or to save energy. But since I was up there, I went ahead and turned it off and back on...and it lit up. I had someone try the faders while I was still on the ladder and the lights worked!

I didn't realize Microsoft made dimmer packs... (/sarc)

Whatever fix it was, everything seems to be happy, so I'm back to programming the show. Thanks again for the help.