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DMX decides to go on strike

Discussion in 'Safety' started by TimMiller, Sep 5, 2008.

  1. TimMiller

    TimMiller Well-Known Member

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    I have told this story before, but i dont know how many of you have heard it. I was doing a show with lamafia, big latin band. We spent a good few days setting it up and everything was going great, besides the dimmer rack throwing out a big blue flash when we turned it on for the first time, but it still worked so we continued on. And that when i went to go pick up soco cable all they had were 150'ers, and i only needs 100'ers. And the boss forgot the truss bolts, so setup was delayed while he drive back from beaumont to louisiana to pick up the bolts. SO After all of that, show time comes along. Not 3 min into the first band we lose all of the DMX to the movers except for the first one in the chain, on our upstage truss. SO after a few songs they take a "break" in which we lower in the entire rig, because everything is swagged together, (upstage, downstage, and line arrays) to replace a dmx cable that was fine for 3 days before the event. After the event when i was pulling the tape off of the rollacue on our avo console, the roller bar quit working.

    Sometimes you wonder if a show is supposed to go on.
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    Kind of makes you wish that DMX was a star topology with redundant loops doesn't it? I guess this is why some places put huge optos on every truss and never daisy chain.

    I have worked on those cursed shows. It always feels like to me that power hits a vacuum in those type of shows, like physics no longer apply.
     
  3. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    I absolutely agree with Footer. Some gigs you get to a point where physics no longer applies (along with any other science). It can be ridiculously frustrating. Using opto splitters on every location is great, but expensive. I guess it always come down to money some how.

    ~Dave
     
  4. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Working with DMX since 1986, I have never seen this practice. It won't protect against a homerun cabling defect. It would also be a lot of 120Ω terminators.
     
  5. Sony

    Sony Active Member

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    this is true, but most moving lights have built in terminators

    I've seen this done once...but it was a HUGE show for The Boston Pops...so they have $$$$$
     
  6. Footer

    Footer Senior Team Senior Team Premium Member

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    I have seen it a few of times, most recently on the East leg of Trans Sib, all of the pods were done this way.
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Not to my knowledge! The only DMX-controlled device I know of with a termination switch is a Sensor Touring Rack. Please state examples and show proof. A quote from the User Manual stating "Brand X's Y fixture has built-in termination" will suffice.

    I knew I should have done more than float motors for that show! I can understand the practice in that case. As I recall, they had a few fixtures of several different brands on each pod, and as we know, certain types of fixtures don't like sharing a DMX daisy-chain with others. Not naming names; they know who they are.
     
    Last edited: Sep 5, 2008
  8. Sony

    Sony Active Member

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    Apollo SmartColor Scrollers have Auto-Terminators in the power supplies (Don't even need to push a button,) so do the Apollo Right Arm's. Those are the ones I can think of off the top of my head.
     
  9. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    I see nothing in the document: http://downloads.goapollo.com/Smart%20Color%20Manual.pdf that indicates auto-termination of the 5pin incoming DMX line. Looping back the 4pin scroller data line is not the same thing as properly terminating the console's DMX line.

    From page 13 of http://downloads.goapollo.com/Right Arm Manual.pdf: "The last DMX device on the line must be terminated with a 120W resistor."

    I've seen various fixtures advertised (falsely) as having auto-termination, but again, to my knowledge, there's no such thing.

    edit: BTW, the above should read "120Ω [ohm]" resistor, not "W [watt]."
     
    Last edited: Sep 22, 2008
  10. Sony

    Sony Active Member

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    We have 12 of the scrollers and 4 of the right arms...I remeber reading somewhere that they have termination built in....I trust it because I've never plugged in a terminator and we've never had a problem....I'm trying to find where I saw it but I'm really tired and irritated right now so I'm sorry if I can't find it...
     
  11. LekoBoy

    LekoBoy Active Member

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    Doesn't mean it has termination built in. There's a poll on here somewhere about whether or not people actually terminate DMX.
     
  12. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I'm sure Mr Fleenor or someone could build an auto terminator for you, at a relevant cost.:evil:

    But what would be a more viable solution would be for Neutrik to start making a mechanical switch version of the 5 pin female so that when a shell was plugged in it opened say and then link a 120R resistor across the DMX via that switch... that would be kinda cool and not all that hard nor terribly expensive to implement...

    The Jands HP12 racks have a termination option in the menu from memory...
     
  13. tomed101

    tomed101 Active Member

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    I know the FP-12's have a termination switch so I would assume the HP-12's do
     
  14. beltsvillecrucib

    beltsvillecrucib Member

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    Was this a show on the road for the Pops? Or Esplanade? I know they don't use this practice at Symphony Hall where the majority of their season is. All VL5's get data from Smart Repeaters while there are two opto's in the ceiling which spit out data to the 5 truss'. One data line for each truss except for I believe 4 which has two. It would be such a pain to run cable for each fixture. Load in would take forever and there would be much added weight.
     
  15. SHARYNF

    SHARYNF Well-Known Member

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    The cause of some DMX issues like this that I have seen is when an xlr cable has the ground connected to the case of the connector, and the connector comes in contact with something with another ground, sometimes it is just a connection that has worked its self loose in the connector and is still providing continuity but is not touching the shell

    Sharyn
     
  16. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Looks like they beat you to it: Neutrik - Industrial - A Series - NC5FAV-SW.
     
  17. dramatech

    dramatech Well-Known Member

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    That is a great idea for a connector, except for DMX termination, it is the wrong gender. The data sheet that is refered to, is for a female connector. Having a terminator at the that point would terminate the DMX data line at the sending end, not the receiving connector, which is a male.
    I couldn't find any such in formation on a male panel connector.
     
  18. Lotos

    Lotos Active Member

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    ...

    The male panel connector is what recieves DMX...
    The female connector transmits DMX...

    Thus, if nothing outgoing is connected to the female connector, a termination occurs.

    That connector would work perfectly for this sort of thing... In fact, now that I've seen those... I'll just have to purchase some, if only to have them in my stock :D
     
  19. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    What an interesting and unique venue/business model! In the US, professional dinner theatres have been slowly becoming extinct over the past thirty years, with a few exceptions like Chanhassen Dinner Theatres. Future producers, take note.

    /end hijack
     
  20. epimetheus

    epimetheus Well-Known Member

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    If only they made this in the solder cup variety...

    This would be perfect for my little DMX project work.
     

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