Control/Dimming EDI Mark VII Rack House/Stage Separation

[Sparkinium]

Hey all,
My high school (which I graduated from several years ago, but still go back to help now and again) has an EDI Mark VII Dimmer Rack. It is set up in such a way that house lights are not controllable via DMX, as far as we've been able to determine. As I'm not around often enough to check on possibilities like the house lights being assigned to ridiculously high dimmer numbers, and due to the total lack of information regarding this rack online, I thought the collective brain-trust here might help me.

My understanding of the rack is that its controller can input DMX, AMX, and several other formats which have gone the way of the Dodo. The rack was installed somewhere around 1993 or 1994, and does appear to have the analog backup controller. The biggest indication that something different is going on with the house lights is that the jumpers on the controller are set differently than the rest of the dimmers.

Other information: There are two racks, for a total of somewhere around 200 dimmers. Like I said, I don't know exact numbers for not being around too often anymore. The lights are currently controlled with several panels, labelled with the EDI logo, with one or more faders and "take control" and "off" buttons. I was unable to find more information on these panels.

How can we determine if it's possible to address the house light dimmers, and if it's not, what steps can we take to make it possible?

Thanks, CB.

 

[dramatech]

I had the exact same problem when I first arrived at my current theatre six years ago.
EDI custom wires the mark VII racks for each installation. The mark VII racks are designed to hold either 60 or 120 dimmer positions. Those positions are controlled by a multi link. The multilink has either one or two circuit boards depending on the configuration. Each board controls 60 dimmers. The dimmer modules have four dimmers each and the first two are wired for one phase and the second two are wired for a second phase.
When house lights are involved in the mix, EDI disconnects the wires coming from the multilink to the connector on the frame where the houslight modules will be located. They then connect wiring from circuit boards that are placed in the back of the rack under the last dimmer module frame. These boards consist of a 15 volt DC power supply. fifteen volts so that power losses in the wiring can be adjusted to 10 volts at the controllers. There is a circuit board that deals with the switching logic of which controller has control of the house lights. There are circuit boards that take the 10 volts coming from the controller logic board, and make it into Pulse Width Modulation, and send it to the dimmer modules assign as houselights. Each of these PWM boards controls two circuits, however it is possible to have a control circuit operate more than one dimmer. In my case, we had four dimmers, or one full module, controlled by two controllers.
I built a new house light dimmer, using some older Electro Control modules and my own controllers. That then freed up the four dimmers in the EDI rack that had been for houselights. In order to get them to work from the multilinks and consequently DMX, I had to remove the dimmer module frame, and disconnect the wiring from the EDI houselight controller circuitry and solder in the wiring from the multilink. The multilink wiring is put in place during manufacturing, but not used when houselights are installed, so it doesn't require running new wiring.
I then controlled the house light dimmer that I built with a relay logic and power supply that I built, and a DMX to analog circuit board from NorthlightDMX.com. This approach would require a new seperate dimmer for houselights.
A couple of years ago one of the high schools in town asked me to come look at their lighting system. They also have an EDI mark VII. They had recently replaced their older EDI console with an Express 125, and didn't like the fact that they still had to have the EDI console in place, just to control the houselights. They had quite a number of 60 amp dimmers in the rack running the houselights, and still needed to have the capability of controlling the house lights from the various positions located around the auditorium. I took a slightly different approach to solving their problem. I installed a DMX to analog circuit board, the same as I had used on my system, in place of the analog controller that was part of the EDI console. I kept the logic buttons from that controller and mounted it all in a project box. This way all of the original controllers around the auditorium still work as designed, but the controller that was the EDI console, now when it takes control, operates the the houselights through DMX from the Express 125.
As much as I was successful on both attempts and each a different approach, I must warn with the strongest language, that I am an electronics engineer, and this is not something that can be done by just anyone. I had some of the schematics, and was able to construct the missing ones through patience and experience.
If you have a very experience electronic technician that can solder well, and can do some testing with a DMM, you can have him contact me at [email protected], and I will discuss the possibilities of him making the modification. I stress, that only if the person has a good understanding of what is required, will I go forward with assistance

 

[Sparkinium]

Thank you. That's the kind of answer I was hoping for. I think the solution where the in-house control panels continue to work will be the most appealing for the space (as permanent modifications to the school building are frowned upon).

The booth is already wired up with the analog backup connector, so hypothetically, I should only need to get from DMX to 0-10V. I read in at least one place while I was looking around that EDI dimmer racks sometimes use 2-10V instead of the standard. Is there any truth to this?

How does the Express "take control?" I know there's a button to do so on the wall panels, as well as an "off" button, but the user's manual doesn't have information on which pins control that.

Edit: I've attached the manuals to this forum post because Cooper Controls no longer lists discontinued products on their website, and finding these manuals was not easy.