Dimmer Problems

I run a small theatre, and we use daisy chained dimmer packs.

3 D4DMXs and 2 DDS 6000s.

Recently the D4DMXs have been developing weird phantom problems.

With some lights, they go full on as soon as I plug them in, whereas others work appropriately (ie responding to my control board)

It began as just one channer on one of the 3 packs 4 months ago. Then it would vary between the 4 channels on that one pack, and now all three of my packs have at least one "phantom" and one pack is completely "phantom" (byt "phantom" I mean the lights are on at full regardless of the control board setting)

Any ideas as to what is causing this...


are you using a dmx terminator on the last pack in the series?
some dimmer packs wont work properly without them, and some go funny if you start using one - so try using a dmx terminator if you're not currently, or try taking the terminator out if you are using one.
hope this helps


Active Member
We had this problem with our installed system in our auditorium. Turns out it was one of the Dimmer Control Cards. It had to be replaced and then it worked fine. Obviously, you have tried a full restart, right?


Well-Known Member
We had a similar problem with our dimmers. We had to go through and reprogram each dimmer rack manually, and they now work (except for some work lights).


Active Member
sounds like a terminator problem. if you dont have one, make one.
other then that, yea, its the control system. you need to get it replaced. contact the dimmer manufacturer support, they'll be able to tell you.


Well-Known Member
Does this happen when your lightboard is pluged in?

Try pulling all data from the dimmer rack, and then plug a light into the dimmer that is not working.

If it happens, it may well be an SSR cube problem as Barewire suggested. If its this, call the company and ask how to fix it. I had this problem on 3 new ETC Smartpacks, and ETC shipped us new powercubes and it was an easy repair.

If it doesn't, it may be a data/termination problem.

If you are using a computer board, make sure you (or someone else) hasn't accidently parked the dimmer at full.


Active Member
A termination problem is very unlikely, the signal would tend to flicker, instead of "locking" the dimmers to a certain level. I agree it must either be a control card issue or the SCR which may have gotten stuck. Still, so many SCRs getting stuck at the same relative time seems kinda extreme.
How old are the dimmers? Maybe its time for a general checkup/cleanup.
Personally, I think its gremlins, after WWII they hand nowhere to go and they invaded the theatres of the world.


One of the packs may be corrupting the DMX signal (unlikely but possible). disconnect all the packs (including the ones that work now) from DMX. Plug one pack at a time into the board and see if you have control. If none of them work ringht then you proably have a board problem or the packs all took a power surge. If all but one pack works correctly plug everything back into DMX except the problem pack and see if you still have any problems. If not you now know which pack needs replace/repair.


Active Member
From your name it appears like your based out of toronto canada i am as well if you are. I would be happy to come by your theatre on an off day or at night affter i am done with the tv show i work on.

if i can be of help
call or email.
416 471 2216 / [email protected]



Active Member
I had a similar problem with a rented system I was using. After frantically talking to the tech. support guy from the rental company we determined that the problem was coming from the board. We solved it by doing a 'deep clear', erasing any and all settings in the board. It was a very small show so this caused me no problems. So if you can risk it, give that a try.


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