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No DMX Signal

Discussion in 'Lighting and Electrics' started by theILLUMINATEDfrog, Jun 6, 2009.

  1. theILLUMINATEDfrog

    theILLUMINATEDfrog Member

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    Location:
    Dallas, Texas, United States
    Using a ETC Smartfade Console and 2 ETC SmartBars .... DMX out to first SmartBar, Daisy chained to second. NO LED Signal from console to either Smartbar...... any suggestions???
     
  2. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    I don't know how similar the SmartFades are to the Express consoles, but I know on Express the DMX outputs are subject to getting fried via voltage spikes and other electrical ungoodness that may be present on the DMX lines, and as such, the PCB that feeds that output may get toasted. If that's the case, most service techs would be able to replace that in a matter of minutes. Again, I'm speaking to Express, I have no experience with SmartFade and can only speculate.

    My advice would be to contact ETC Tech Support @ 1.800.444.8825. That's a good number to keep in your address book; I keep it on my cell phone, and almost every piece of equipment comes with that number printed on it. Even the distribution boxes we ordered recently had that number on it. They have a 24/7 pager that gets passed around the different service techs, so please use it wisely and save non-emergency calls for regular business hours.
     
  3. theILLUMINATEDfrog

    theILLUMINATEDfrog Member

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    My issue has been solved! Just so others know, there are two small "dimmer chips" (as called by the tech support guy) that can be switched (probably the same PSBs you referred to)-- since I was only using the DMX OUT from the board, I was able to swap the two chips (the other for DMX In) and signal flowed freely. Very simple fix, but would have never known w/o talking to a service guy... things like that should be in the manuals. I will still have to buy a new chip or whatever when the need for the DMX In arises but for now, LET THERE BE LIGHT!
     
  4. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    So it is the same as Express. That doesn't surprise me too much. They've told us the same thing. "If one fails, just program Universe 2 onto channels 1-512, and then if you ever need Universe 1 again, have the chip replaced."
     
  5. DimmerDotCom

    DimmerDotCom Active Member

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    They are just RS485 transceiver IC's. Any company who makes DMX capable equipment should always provide these IC's in their products as socketted dual in line packages (the IC's with the metal legs that point down and can be removed with a flat blade screwdriver if you do not have a chip puller) IMHO. Quick fixes to be sure. For touring customers sometimes we would glue another chip upsidedown to the one actually being used. So if it blew, a tech could just pry the chip off and flip it over and away you go.

    These transceiver IC's often blow because of ground loops. If your console is on one power source and your dimmers are on another, the different sources of power can have ground at different potentials (ask anyone in audio about the fun with ground loops). On stages or shoots we see this when some stuff is on house power and some on generator. Opto isolators are your friends in these cases.

    Example: a few years ago I has a Strand GSX console and a Strand CD80 dimemr pack blow. the transceiver chip in the pack controller blew (easy fix), the transceiver chip in the GSX console also blew but a hole was burnt completely through the circuit board because the earth potential on the dimmer ground found a path to the booth's ground because DC common was connected to the chassis via a 100ohm resistor. Shouldn't cause a problem because the GSX has a power brick and as such has no earth ground. So what happened? When the VGA monitor is connected, the GSX chassis is grounded via the shell and the ground pin in the VGA HD-DB15 connector. Oops. Booth ground was not the same as ground in the electrical closet back stage. Double oops.

    REad the number off the IC and oder one or two from a vendor and place them inside the chassis (secured of course) of your console or dimmer pack, etc. for future emergencies - not that I like making easy money on easy repairs, but I hate to see cash strapped churches, schools, and small theaters spend money when they are ill equipped to do so.

    Maurice Garcia
    dimmer.com Home Page
     
  6. abbyt

    abbyt Member

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    Occupation:
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    Location:
    Greater Cincinnati, Ohio area, United States
    Typically, RS485 Transceiver chips are 75176's (and while we're at it, opto-chips are typically 6N137). Available from most any ighting dealer or manufacturer, and available at places, at least in the US, like Digikey, Mouser, and Newark. Prices can vary due to quantity of purchase, where you purchase from, and manufacturer of the chip, but usually run anywhere from 50 cents to a couple dollars, excluding shipping.

    DMX chips are almost always socket-mounted, and with care, *usually* can be relatively easily replaced in the field, provided the chip gets installed the right direction, and each of the pins goes in its respective slot properly, and without bending.

    I went on a service call once...the customer had some gear down after a storm. He had been sent DMX chips from the manufacturer, which didn't fix the issue, so he called me out to repair his system. Turns out that blown chips were, in fact, the issue, but when he installed the new ones, both chips he replaced had gotten one or two of their pins bent underneath themselves, so they didn't work.

    Glad you got your equipment working!

    -Abby
     
  7. jmabray

    jmabray Active Member

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    Gee, Ray, you could have just called me and I would have been glad to help you out. I can bring you a chip on Monday if you like.

    :)

    Jeff
     
  8. JD

    JD Well-Known Member

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    Location:
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    Sounds like something you might want to take a couple of spares, put in an anti-static bag, and mount the bag inside the board! Boy, I would hate to be out on the road somewhere, go to fire things up and find out I'm about to get sued by the promoter because the show's about to get canceled because a $1 chip just failed!

    (Of course we all know, never leave the shop with just one board!)
     

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