Control/Dimming Lights dim as each new light is added to cue

[havelina]

Had a 2 scene preset on an old analog system of Decor dimmers. Added the Producer 3 to that with Dove DMX translators. Just added an ETC Expression 3 and now each time I add a light to the cue at full both lights lose intensity. Once I get to 10 or more lights there is almost no light on stage even though they are all at 'full' on the screen. Still have to use the Dove DMX translator for the analog signal.
First thought is the pin assignments between the Dove and the Expression.
Would love some help.
Thanks

 

[dcollins]

Had a 2 scene preset on an old analog system of Decor dimmers. Added the Producer 3 to that with Dove DMX translators. Just added an ETC Expression 3 and now each time I add a light to the cue at full both lights lose intensity. Once I get to 10 or more lights there is almost no light on stage even though they are all at 'full' on the screen. Still have to use the Dove DMX translator for the analog signal.
First thought is the pin assignments between the Dove and the Expression.
Would love some help.
Thanks

Do they dim significantly? A sudden power draw can easily cause a voltage drop, although that's usually on the order of a few volts - enough to notice a brief dimming, as though everything had gone down to 80-90%, it sounds like you're describing something more than that.

Here's a quick diagnostic:

You say the problem is visible with ten lights. Start by turning on one light, any light, and look at how bright it is. Then turn on ten other units and observe how much that first light dims. Next, shut off the ten other units you turned on, unplug them, and turn those other channels back on from the board. If the first channel still dims when you turn the other channels up, even with the other lights unplugged, the problem is somewhere between the board and the dimmers. If the first channel does not get dimmer, then your problem is a voltage drop - a 'brownout', albeit a rather localized one - and you need to chat with an electrician.

If it's the first case there are probably a few possibilities, but I can't think of any very likely ones at the moment, and I don't care to speculate too wildly. Components getting old and breaking down is a fact of life though, it's possible that part of your system is past its useful life.

 

[David Ashton]

I would suspect a dry joint on the common line out of your Dove demux, power drop on the power side of the dimmer is most unlikely.A dmx problem is virtually impossible.

 

[STEVETERRY]

I would suspect a dry joint on the common line out of your Dove demux, power drop on the power side of the dimmer is most unlikely.A dmx problem is virtually impossible.

I agree--it's probably an open or mis-wired signal common.

ST

 

[JChenault]

I am not intimately familiar with the decor line of dimmers, but assuming they use low voltage analog control, the problem could be as simple as dirty / corroded pins in your connector. You might try cleaning them.

 

[LightingTechie]

Re: Odd behavior- DMX & Old dimmers

I sense a control problem. I doubt it has anything to do with your dimmers if your demux has worked with them before. Have you tried checking the wiring on the demux? Something on the signal common? But then it could be a voltage drop because of the sudden power draw but that is unlikely.

 

[JD]

Re: Odd behavior- DMX & Old dimmers

Sounds an awful lot like an analog problem in the output of the DOVE. Just happen to occur when you were making the changeover. First, check your connectors on the analog side of things. Not sure right off hand, but the dimmers sound like 0-10 vdc dimmers. A failure of the dc supply in the DOVE that provides the +15 volt buss could cause it. As additional A/D drivers call for their .5ma piece of the pie, the supply buckles. Might be a bad pc land, or as said before, dirty connector with high resistance on the common pin.

Cheap fix- Unplug and re-seat the analog output connector(s). If that works, hit them with contact cleaner.

Beyond that, you would have to get a read on what DC voltage the outputs on the DOVE are giving, and if it changes as you add more channels.

 

[Les]

Re: Odd behavior- DMX & Old dimmers

The Producer III was (is?) manufactured by Teatronics, no?

http://www.teatronics.com/products/10.html

 

[mstaylor]

Could it be a matter of it outputing 10v but should be some other voltages? It's the only other thing of the top of my head except what has been suggested.

 

[jstandfast]

I would join Mr Terry and others in speculation about this being a " common problem".
I have several times had similar problems with both DMX and AMX demux/sample-hold
devices, mix/matched w/various analog dimmers. Usually boils down to differing wiring
standards for cinch/jones connectors- maker to maker.

 

[FatherMurphy]

I'll go along with the general suspicion that it's a problem with the common wire in the analog cabling. For most analog dimmers, when the common is broken or not making contact, the signal current for one 'on' dimmer is more or less able to flow back along along the wires for the 'off' dimmers, but as more and more dimmers are turned on, the available paths are reduced and the electrons become gridlocked, with the result of lights getting darker and darker as more channels are added, just as you are experiencing.

If the problem is minor corrosion on the analog control plugs, simply plugging and unplugging the connectors several times will often self-clean the contacts. Also check to make sure that plugs are fully seated, as simply being loose in the receptacle can cause an incomplete circuit.

The second main possibility is a broken wire inside one or more of the cables. You can either open the connector shells and look for obvious things like wire ends floating around loose inside, or use a voltmeter to check for continuity between the corresponding pins on either end of the cable. Wires do occasionally break mid-cable, but that is rare without visible damage or long-term abuse. If the cable is a fanout (one big plug breaking down into several smaller plugs), some research into how they're pinned out might be needed.

More information about what exact model numbers of your equipment, and what sorts of connectors are being used might be helpful for further troubleshooting assistance here.