The above Ad will no longer appear after you Sign Up for Free!

Lights go black when sound system comes on

Discussion in 'Lighting and Electrics' started by RedmonwantsEOS, Dec 14, 2007.

  1. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    Has anybody ever encountered a problem like this?
    Whenever our lighting board is off and the power to our sound system is turned on, whatever lights are on go black for about one second, then come right back on. BUT, if the light board is already on, this problem does not occour. BUT, if the DMX cable is removed from the light board, while it is off, the problem does not occour.
    Anybody seen anything else like this?
    Lighting system is a Lehigh DX2 system with 6 preset recall stations, a CT500 Master Touch Station, and MillenniumXP console. This is pluged into a surge protector.
    Sound system is protected by a NADY PCL power conditioner, and supplies a Soundcraft Venue Theater board, and 2 Numark CD Players.
    Thanks for your help!
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

    Messages:
    9,392
    Likes Received:
    1,789
    Location:
    Saratoga Springs, NY
    Odds are you are having a power drop when you turn your sound system on that is shutting off your board for a second or two. When you unplug the DMX, the dimmers are holding all the values that you were giving them untill it starts receiving DMX again. My advice, find a different circuit to plug your lighting console or sound system into.
     
  3. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    But see, the light board is off when the problem happens, it doesn't happen when the board is off.
     
  4. Footer

    Footer Senior Team Senior Team Premium Member

    Messages:
    9,392
    Likes Received:
    1,789
    Location:
    Saratoga Springs, NY
    So... I assume you have an architectural control system that is turning the lights on? Sounds like there is something that the console is doing when you power up. Try unplugging your lighting console from power and leave the DMX plugged in, see if it still does it then. Remember, power supplies never really shut off.
     
  5. wolf825

    wolf825 Senior Team Emeritus Premium Member

    Messages:
    1,155
    Likes Received:
    93
    Location:
    Eastcoast USA

    Are your Sound and Lighting board coming off the same power earth ground? Sounds like they are sharing the same feed (tho they may be separate breakered circuits if you are lucky, the ground or neutral may be lifted, tied or crossed somehow by some faulty wiring down the line somewhere.. What gives me this indication is you say when you unplug the DMX line this does not occur...which tells me any inturruption you may be getting is either a power drain as others have suggested--OR more likely a voltage spike on the ground/neutral when you power up which is carried down the DMX line. Are things being turned on sequentially(console, outboard then amps etc), or is it "everything on" with one switch?

    This may or may not be the problem--and unfortunately thats about the best suggestion I can figure to tell you without being able to meter voltage or SEE the situation, is to trace all your AC cables, wall outlets, power strips (some of the CHEAP ones can really give you a problem) and plugs etc, and get your wiring checked for any lifted, shoddy or bonded ground/neutrals leading into or out of in your booth and breaker panel...and best scenario is to put your Sound on a different breakered source from your Dimming and control...

    -w
     
    Last edited: Dec 15, 2007
  6. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    wolf825,
    I wouldn't be suprised if there was some faulty wiring, as this school is fairly old. Yes, I am fairly certian that the light and sound boards are on the same circut. But, the actual lights (House and Stage) are fed from a completly seperate, 240 volt, 400 amp feed. Usually, we power on the light board first (to avoid the blackout), then the sound board, and then the sound amps.

    Footer4321,
    You are correct about the architectural control system.

    Thanks for your help so far!
     
  7. wolf825

    wolf825 Senior Team Emeritus Premium Member

    Messages:
    1,155
    Likes Received:
    93
    Location:
    Eastcoast USA

    Fairly old...well if the wall outlets are vinatge could be the source of your problem should be it a ground differential.. Older wiriing could have used anything for a ground...and often neutrals were daisy chained from outlet to outlet or tied--which would leave you possible issues... May wish to get an electrician out to check things and trace things.

    -w
     
  8. Footer

    Footer Senior Team Senior Team Premium Member

    Messages:
    9,392
    Likes Received:
    1,789
    Location:
    Saratoga Springs, NY
    Just a note, it should be a 208v service, not 240.
     
  9. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    It might be 208, I don't know. It comes out of a 150Kva transformer in two conduits, then goes into a disconnect rated at 240 volts, 400 amps.
     
  10. avkid

    avkid Not a New User Fight Leukemia

    Messages:
    5,948
    Likes Received:
    225
    Occupation:
    Stagehand/ Production Company Owner
    Location:
    Howell, NJ
    Of course, wiring should always be rated higher than it's intended use calls for.
     
  11. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    Ok, I know this is an old thread, but due to some recent activty at my school, I have new information that might lead to a solution.
    The two duplex outlets that we use for the lighting console and sound board are fed off of a dimmer circuit (long story, see "The Mystery Circut" in the "What Wnt Wrong?" Forum) that is a Lehigh Constant Module Dimmer, the only one in our dimmer rack. The outlet for the light board has hot, neutral, and ground, and the one we use for sound is daisy chanied off of it, but only with a hot and neutral. Could this be the source of our problem?

    Oh, and the dimmer feed is fed from a 480 volt, 200 amp, 3 phase circut, goes into a transformer, and comes out as 120/208Y, 400 amp, 3 phase+neutral, 4 wire total.
     
  12. FMEng

    FMEng Well-Known Member Fight Leukemia

    Messages:
    1,730
    Likes Received:
    491
    Location:
    Tacoma, WA
    This sounds like a grounding issue. Somehow, the audio console is inducing some noise into the DMX cable. It could be a ground loop, or caused by an open AC ground. It would be intereting to unplug the DMX cable, and test the AC outlet for continuity of the ground. If the circuit ground is good, this is probably more of a curiousity.

    Having the booth power fed from a non-dim module isn't great, and if you can get that changed, it would be a good thing to do. But, it isn't necessary.

    You mention that the sound console's outlet is not grounded. That's a safety hazard which needs to be repaired by a competent electrician. If repairing the ground causes a hum problem in the sound system (wouldn't be surprising), that should be solved by other means than lifting the safety ground.
     
    Last edited: Jun 17, 2008
  13. David Ashton

    David Ashton Active Member

    Messages:
    826
    Likes Received:
    87
    Occupation:
    truck driver
    Location:
    perth W Australia
    It is not a grounding issue and it is totally easy to explain, when the sound is turned on the inrush current over a probably too small wire, causes volt drop which takes the desk down briefly, to check try running the light desk off an extension cord from another socket [on another circuit]Dmx is not connected to earth, only the screen is earthed.
     
  14. RedmonwantsEOS

    RedmonwantsEOS Member

    Messages:
    46
    Likes Received:
    5
    Well everything has now been removed from the booth in anticipation of renovations over the summer. Which WILL include new outlets not connected to the dimmer gear :)
     

Share This Page