CD80 Non-Dim Modules and D60 Vivids

Hey guys,

I recently took over as ME in my theater. We currently have four CD80 racks and an ION.

I have requested the purchase of some D60 Vivids to replace our 2K Fresnels in our Rep Plot. The problem I have come across is powering them as we do not have enough wall power to do this.

I know the best option is the Johnson Systems relay modules, but that would require us to also replace our processors and we simply do not have the money to do that right now and there is also nothing wrong with them.

I found out this week that the previous ME had modified two of our Non-Dim modules (by bypassing the choke) to power our Colorforce II’s. I personally do not feel comfortable doing this. So I am wondering if there is a better way to power the D60s? Are there any other relay modules out there that are compatible with CD80 racks that I can use without replacing our processors? Is it safe to use the few Non-Dim modules we have, with this being a permanent/long term hang? If so are there any vendors out there that still sell Non-Dims for CD80s?

Any help, thoughts and opinions are very much appreciated!

Thanks,
Angie
 
Hey guys,

I recently took over as ME in my theater. We currently have four CD80 racks and an ION.

I have requested the purchase of some D60 Vivids to replace our 2K Fresnels in our Rep Plot. The problem I have come across is powering them as we do not have enough wall power to do this.

I know the best option is the Johnson Systems relay modules, but that would require us to also replace our processors and we simply do not have the money to do that right now and there is also nothing wrong with them.

I found out this week that the previous ME had modified two of our Non-Dim modules (by bypassing the choke) to power our Colorforce II’s. I personally do not feel comfortable doing this. So I am wondering if there is a better way to power the D60s? Are there any other relay modules out there that are compatible with CD80 racks that I can use without replacing our processors? Is it safe to use the few Non-Dim modules we have, with this being a permanent/long term hang? If so are there any vendors out there that still sell Non-Dims for CD80s?

Any help, thoughts and opinions are very much appreciated!

Thanks,
Angie
Calling @Ron Foley Ron; Possibly you can help poster @Angela Lianzo
Toodleoo!
Ron Hebbard
 
Your existing modules will work just fine. If you are still running on the original processors, I'd suggest to start planning/budgeting now for an upgrade to the JS kits. Your current processors will work perfectly fine.... and then catastrophically fail (and I swear to God it's always right before a show).
 
I have CD80 racks.

I love Steve! He did amazing work at my old theater. We’re in the process of scheduling him to come in and talk about upgrading options, but for the time being we need a solution to get the D60s up and running this summer.

My gut instinct was that our current non-dims were fine but I guess I started second guessing myself when my boss told me the old Electrican was very adamant that the non-dims needed to be modified.
 
The choke in a dimmer module serves two purposes: the primary and more familiar one is an attempt to reduce filament noise in incandescent lamps caused by SCR dimming. The secondary role is to increase the amount of fault current the dimmer module can handle. Circuit breakers don't trip instantaneously, and (depending on a whole lot of complicated factors) a massive amount of current can flow through the module in a worst-case failure scenario. The choke helps limit just how much current can flow in that brief moment before the breaker trips, and therefore limits the amount of damage that fault current can cause. If you bypass the choke, then a worst-case fault could create a much more dangerous situation.

The downside to leaving the choke in place and just bypassing the SCR is that some electronic power supplies can interact with the choke in a way that is bad for them. ETC fixtures aren't likely to have this problem because ETC tests their fixtures with their dimmer modules set to non-dim mode. However, other fixtures could be damaged by this interaction, and most fixture manufacturers don't do the testing required to know for sure how they will behave.

Modern relay & constant current modules get around this problem by replacing the choke with a fuse. At first glance this looks really silly because you have a fuse in series with a circuit breaker, but the fuse will have a higher rating than the breaker. This means that a normal overload (like someone putting 25A on a 20A module) will trip the breaker rather than blow the fuse. However, even though the nominal current rating is higher for the fuse, it will still react significantly faster than the breaker when you have a worst-case fault condition. This limits the amount of time that massive current can flow and helps prevent more catastrophic damage.
 
Or amp trap fuses on the rack - which used to be the standard - when high density modular dimmers were the new thing.

Similar, but slightly different: amp trap fuses let you buss together multiple racks with a larger feed than you could bring into an individual rack. An example would be a single 1200A feed shared across four racks that are each rated for 800A max. Horizontal buss bars pass through all four racks and amp trap fuses in each rack connect that horizontal buss to the vertical bars feeding individual dimmer modules.

It's all the same concept, though, of determining just how much current can flow through something before it fails in an unsafe fashion. The UL requirements allow for the equipment itself to be damaged beyond repair, but it shouldn't start on fire or eject pieces when that happens. Needless to say, these are fun tests to watch :)
 

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