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Control/Dimming Need some help with an NSI DDS 6000

Discussion in 'Lighting and Electrics' started by jaredmolson, Aug 20, 2008.

  1. jaredmolson

    jaredmolson Member

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    Hello. I'm new to these forums and new to the lighting world. I'm currently working with a relatively small stage at a church, and I am attempting to use a light bar that had been installed before I started working here.

    We have 3 NSI DDS 6000 dimmer packs (4 channels per pack, 2 inputs per channel, 1200W per channel) on our light bar. On one of the packs, two of the channels are dead. When I plug a working light (500W PAR64, MFL) in from another working channel, nothing happens on either input.

    Aside from checking and replacing the fuses, is there anything else that I can do to get those channels working again, or anything else to check or verify? I'd rather not have to send the pack to NSI, but I also don't have a lot of electronics experience, so I wouldn't be able to do a major fix myself.

    Thanks for any suggestions.
     
  2. Sony

    Sony Active Member

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    I've used the 6000+ before and they aren't well known for their reliability however if I were to wager a guess I would say that one of the SCR's is burnt out. Usually each SCR controls 2 channels, and they are what do the actual dimming. What would suggest is opening the unit up and checking to make sure there are no loose control wires or any loose wires at all and if that doesn't work then I would replace the SCR. SCR's are pretty easy to find just need to know where to look. Usually they are also easy to replace since they are just screwed onto the case and the wires connect via crimp connectors.

    Hope this helps!
     
  3. waynehoskins

    waynehoskins Active Member

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    ?

    That doesn't make sense to me. I believe it takes two SCRs to PWM-dim a single output. It's a three-terminal device; I don't see how they could be using a single SCR to do anything on two output channels.

    But yes, my vote is:
    (1) Check the fuses. Cheapest fix.
    (2) Possibly addressing problems?
    (3) Failing that, you've got blown-up power devices.
     
  4. Sony

    Sony Active Member

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    Sorry...I should have clarified

    Each SCR Module in the 6000 are two SCR's built into one unit. Unfortunately usually when one dies it takes out the other one too. The three terminals are Mains In, Dimmer Out and Control so the SCR's in the 6000 have 6 terminals...2 of each type.

    Also it is possible for one SCR to dim 2 fixtures, just ask how ETC Dimmer Doubling works.
     
  5. JD

    JD Well-Known Member

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    Yea, actually a triac, usually part number BTA16-600B
    When they go, they usually blow in the "on" mode, as in the light is full on. They can go open circuit, but not too often. I would check a few other things first to make sure they are being told to turn on, such as setting the DMX to 1 and making sure there is not an active patch on the board that might be masking the channels. Good luck.
     
  6. waynehoskins

    waynehoskins Active Member

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    Ah, gotcha. Though they'd be double triacs or double SSRs, right? Or maybe double paired-SCRs? In any event, that makes more sense now.

    I've always wondered how they did dimmer-doubling. I've thought of a few crazy ways it might work, but never actually researched it.
     

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