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Control/Dimming LED Fixture Control

Discussion in 'Lighting and Electrics' started by DCATTechie, Jun 23, 2008.

  1. DCATTechie

    DCATTechie Active Member

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    Dublin, OH
    We just got 15 LED Par's for our "Little Theatre" and to my dismay, they have 3-pin (is it still called DMX?) "control" inputs and outputs. I'm planning to control these off of a Leprecon LP-624 which has a 5-pin DMX port in addition to a 3-pin Microplex port. Can i control these LED's with the Microplex? If not, how would you advise controlling them from the 5-pin DMX port.To make this more complicated, I also have 4 Altman 6" Fresnels that I need to control off of the same board. Should I invest in a DMX splitter or not? What are my options? All help is appreciated. Thanks!!
  2. jmabray

    jmabray Active Member

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    Dallas, Texas
    It is probably DMX, although it doesn't meet the standard. The standard says that you should use a 5 pin XLR style connector. However, you are really only using 3 of those 5 pins. So what you need to do is get a 5 - 3 pin adapter. Put it after the other fixtures in your DMX run, and then use 3 pin DMX cable (NOT MIC CABLE, THERE IS A DIFFERENCE) to go from fixture to fixture....
  3. soundlight

    soundlight Well-Known Member

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    NJ & NYC
    You need one of these handy-dandy little adapters to go from 5 pin DMX to 3 pin control, along with some 3-pin signal cable. Our own BillESC sells 5-packs of 5 foot and 10 foot 3-pin signal cable. GoDirectMusic has 25' and 50' 3 pin "DMX" cables for decent prices. They also have cable-style 5-3 and 3-5 adapters if you don't like the barrel style adapters.

    DO NOT use the Microplex/MPX signal to control the LED pars. You run the risk of killing the fixtures.
  4. porkchop

    porkchop Well-Known Member

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    The two previous posts nailed it, standardized DMX signal only utilizes 3 of the 5 pins so it is common to see simpler DMX toys (color scrollers being the ones that come to mind instantly) with only a three pin connector. This is a pain in that you now need to buy and adapter or two and may need to build/but a three pin terminator (you are terminating your DMX signal right?), but it is also a good thing in that you are likely to find 3 wire cable to be cheaper and although there is a difference should you find yourself in a pinch you can use three pin mic cable to make your DMX run.

    SHARYNF Well-Known Member

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    Here is another suggestion:
    If you have a console with 3 pin out Microplex and you also run 5 pin and 3 pin dmx do your self a favor and get an opto isolator dmx splitter. The reason for this suggestion is that some day someone is bound to plug the 3 pin dmx into the 3 pin microplex and the 20 volts on the microplex system is going to destroy the dmx devices. even the cheap Chauvet splitter has isolation, offers 3 and 5 pin in and two sets of 3 and 5 pin out with the option to reverse for say some of the older martin units.

    Bills units are great IF IMHO you do NOT HAVE ANY MICROPLEX DEVICES.

    Just a suggestion

  6. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Las Vegas, NV, USA
    Wrong again there, prokchopper [sic]. Name one color scroller that uses 3pin XLR. Not even the ColorMax or ColorWiz, (way before your time; and predating USITT DMX512-1986) used 3pin XLR. The only readily available scroller that took DMX directly, Wybron's The Scroller™, had 5pin XLR.
  7. BillESC

    BillESC Well-Known Member Premium Member

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    Kilmarnock, VA
    3 to 5 and 5 to 3 DMX adapters are available and easily had as are longer runs of real DMX (120 Ohm) cable.
  8. SteveB

    SteveB Well-Known Member

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    Brooklyn, NY
    Having faced the same situation with my High End Studio Spots a few years back, I opted to put cable adapters male 3 to female 5 and the reverse on every fixture. I know it's expensive - at around $50 per fixture, but it lets me standardize the use of 5 pin DMX cable everywhere.

    I like the cable adapters better then the ones Soundlight recommends, as there's less strain on the fixture connector.

    Steve B.
  9. len

    len Well-Known Member

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    Likely each fixture needs a minimum of 4 dmx channels. Most are R = 1, G = 2, B = 3, Dimmer/strobe = 4. Some better led pars need 6. So a 624 isn't the best call, unless you can live with multiple cans on the same address.

    And it's very common for LED and a lot of other types of fixtures more targeted for the dj and small band market to have a 3 pin xlr input which is "dmx". As we all know, 3 pin xlr is much more common. While one shouldn't use mic or instrument cable for dmx, most of us in event production do it all the time. HOWEVER, we know that most problems could be avoided by real 5-pin dmx, but the boss looks at the cost of purchasing 5 pin data vs the extra time it takes to troubleshoot the occasional problem and opts for the 3-pin.

    As for adapters, I prefer a 1' or so cord, as opposed to a barrel. They seem to lay flatter, etc. and I think there's less chance of one snapping off a fixture, although that's never actually happened. I have Bill make them up (and I'll be ordering some more shortly) because I'm not the best solderer in the world. Actually, I'm the worst solderer.
    Last edited: Jun 24, 2008
  10. TimMiller

    TimMiller Well-Known Member

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    Houston, Tx
    at our shop, we are really big into fabrication, probably why we work out of a 214,000 sq foot manufacturing facility. We modded our studio spots to take 5 pin dmx rather than 3 pin. Throws the rest of the world for a loop :D.

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