Control/Dimming Lights ghosting when board off

This is called ghosting and it's pretty common in older spaces. For me it's always been a "I would love to fix this, but I can't spend any money to fix it... so I won't" problem.
 
2004 is model #

Is this an EC Quad rack, meaning three vertical columns of 16 silver-faced dimmer modules with 4 circuit breakers on each module? A card cage in the bottom with several control modules filling it? A big blower at the top exhausting out the front?
 

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What is your control system? Meaning Lighting Controller---how it connects to the dimmers---anything else between it and the dimmers? If you turn on the system are the same dimmers still ghosting? Are they always the same? Or do they only ghost after your turn the system off? Besides dimmers getting cranky, there are a few control things that could cause this to happen.
 
Yes, many systems have "trim" settings in the pack, board, or both. These allow you to lower the cold inrush surge by pre-heating (idle) the lights as well as get rid of the perceived "dead" area near the bottom of the dimmer curve. If it is set wrong in any location, or if the value has drifted, you will end up with visible light at black, or a dead area at the bottom of the fader.
 
Is this an EC Quad rack, meaning three vertical columns of 16 silver-faced dimmer modules with 4 circuit breakers on each module? A card cage in the bottom with several control modules filling it? A big blower at the top exhausting out the front?
Yes, exactly that. Sorry for delays, I'm only here part-time.
 
Usually it takes no money and just a little bit of time and care to fix ghosting problems. Almost every dimmer has a method for doing this. It is best to find the documentation for your particular dimmer. It is often a simple adjustment but can sometimes be caused by a parts failure.

On an EC Quad rack you should be able to fix the ghosting by the following process. This assumes the problem is with the dimmers and not the console or some kind of converter.

Each vertical column of dimmers is controlled by a PC341 ramp module in the bottom card cage. The three ramp modules look like the illustration and are near the center of the card cage. The left ramp module controls the left column of dimmers, center controls center, etc.

Starting with the left column, attach a 500-1000 watt fixture to one of the dimmers circuits. Make sure the control console is turned off or the master is down.
The fixture ghosts.
The high and low trim pots are behind the 2nd and 5th faceplate slots as shown. Use a very small slotted screwdriver (preferably with a plastic shaft since you are inserting it near a live pc board) to adjust the low pot. You will have to get down on your hands and knees with a flashlight to get the screwdriver lined up. Note the relative position of your screwdriver in case you have to return to the original setting. Be very careful not to use much front to back pressure because the pots are very fragile and are just held on to the pc board by their leads with no other support. I can’t remember which way to turn the pot but with very little rotation you will either see the load dim or brighten. This not a multi-turn pot and is very sensitive to adjustment. Usually an eighth of a turn or less will make something happen.

Sometimes these pots will become intermittent after many years and cause an entire column of dimmers to malfunction. This low end adjustment can interact with the high end adjustment, so be sure to carefully run the channel up and down on the console while observing the load before you move to the next column of dimmers.

If you end up bending the pot backwards and need to straighten it up, you MUST kill power to the rack before you remove the top left module retaining screw and pull the ramp module out to bend it back. If you do not feel comfortable killing the power or removing the module, please seek help from a qualified person.

This may be more information than you need.
 

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I'll add one thing to the above post- The light may jump on or go to black the second you touch it. This indicates the trimmer pot may be a bit dirty. If this happens, rock the setting back and forth a few times, slightly below and above where you want it to be. This is usually enough to clean the area of the pot you are adjusting and allow you to do the fine adjustment needed to set the black level. (Same may also be true with the high-end trim pot.) Don't panic if you see this jump. Needless to say, since you are setting the ramp/trim for 1/3 of the whole rack, you may want to turn the breakers off on all but one of the channels so you don't have an accidental light show ;)
 

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