Lee Colortran Dimmer Issue (kind of odd)

[DuckJordan]

I went and saw a production from my high school and found a curious problem that has not happened before while i was at the school. Our under balcony house lights didn't dim. When they house lights faded they stayed on till the very end at full then just flipped off like they were on a switch. This is connected through an old analog to DMX box located by the rack, its controlled by a fader box which as i understand it uses the 10v system to send signals to the controller then from the analog controller to the DMX unit in the dimmer rack, these are 15 years old not sure what they are.

unfortunately it won't be until Saturday that i can get into the space to work on anything or even investigate the problem. It never happened before but we did recently clean the dimmer rack this last spring. which we received some issue with the analog box not controlling the specific dimmers in question which itself was fairly random.

I will check the system on Saturday but my question is if anyone else has had this issue and what caused it.

 

[JD]

Analog dimmers use what is known as a "ramp generator" (Often, one per dimmer module.) A failure in this circuit can cause the symptom you described. Sometimes, this failure is nothing more than a dirty low end or high end trim pot, and it just needs to be turned back and forth a few times. Also, if someone tried to adjust the card and was too rough, they may have damaged the pot. No ramp = no dimmer curve. It is a very simple circuit to repair provided you can link up with a good service center.

 

[DuckJordan]

Analog dimmers use what is known as a "ramp generator" (Often, one per dimmer module.) A failure in this circuit can cause the symptom you described. Sometimes, this failure is nothing more than a dirty low end or high end trim pot, and it just needs to be turned back and forth a few times. Also, if someone tried to adjust the card and was too rough, they may have damaged the pot. No ramp = no dimmer curve. It is a very simple circuit to repair provided you can link up with a good service center.

I think we are talking about two different systems here, First off the Analog card is not in itself a dimmer, all the dimmers in question are DMX controlled, the analog card is just used to carry the signal from the wall mounted fader box to the Colortran rack, not actually dim the lights.

There is also no adjustable parts as its just a analog to digital converter card. It only happens with the lights underneath the balcony and not the rest (all controlled by the card itself then to the dmx control units in the rack.

The signal flow would go as follows

Analog faders (2 of them different locations, and requires use of a "take control" button) to the analog to digital converter, then to the DMX control modules on the Colortran rack, then to the dimmers to the house lights.

 

[JD]

Ah! Thanks for the clarification, I did misread the post. Check to see if that channel has been switched to the "Relay" mode. In that mode, anything above a certain DMX value will be considered "on."

 

[DuckJordan]

Ah! Thanks for the clarification, I did misread the post. Check to see if that channel has been switched to the "Relay" mode. In that mode, anything above a certain DMX value will be considered "on."

I'll have to do that when i get in on saturday, Although the only control of the house lights is through that 20 year old box is it possible its been set that way on the dimmer control modules on the Colortran rack?

 

[PatrickAngle]

Having the exact same problem in our auditorium, controlled by Colortran Dimmers. The house lights under our control booth are behaving in a way that causes some of them to fade, and some of them to jump. We only have this problem when controlling the lights through our Colortran Encore console. When controlling lights using our house sliders that are independent of our board, we don't have this problem, and the problem is currently only noticeable on two dimmer's worth of house lights (6 lights).

If you have found a solution to the problem, I'd love to hear it. We are in middle of a 3 day run of 'White Christmas', and house lights are designed to come up in middle of the show for a scene.

 

[starksk]

... We only have this problem when controlling the lights through our Colortran Encore console. When controlling lights using our house sliders that are independent of our board, we don't have this problem, and the problem is currently only noticeable on two dimmer's worth of house lights (6 lights)...

I am not familiar with the Colortran Encore so perhaps Titanium can provide a more detailed answer, but as it is only occurring when it is controlled through the console and not through the wall stations, I would check to see if there is a dimmer curve assigned to those outputs in the console. On other consoles, a dimming curve (also called a profile) can be applied to change the way a specific dimmer or dimmers react to a percentage on the console instead of changing it at the dimmer rack. It may be possible to assign something like that on the Encore console.

 

[Madzoga]

You can set up the dimmers to be non-dim on the rack control module. Probably, someone was cleaning the rack and moved the switches by mistake.
If the rack is a 96, then the top control module control top half of rack, bottom does bottom.