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Weird problem I can't explain.

Discussion in 'Lighting and Electrics' started by gabe, Nov 17, 2006.

  1. gabe

    gabe Member

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    So when my show opens theres a special on stage, it lit up fine for the opening, but when it's used about 10 min. later it wouldn't come on. So I thought, "The lamp blew, no biggie." I change it at intermission and it's used first thing in act 2 it comes on fine at first, but then the second time it's used in act two it doesn't work. Now I have never seen anything like this, anyone have any thoughts?
     
  2. cutlunch

    cutlunch Active Member

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    Please supply more information to help us solve this problem. For a start what make and model is this lamp? What wattage? What dimmers are you using? What control board? Do you have a spare channel on the dimmers you can try it on?

    My first thought is probably a problem with a dimmer channel. That's why I suggest you try it on another channel.
    Also have you had the lamp fixture checked recently? Is it safe? Although unlikely the there could be a faulty connection which loses contact when the fixture is hot.

    I also looked at your old post where you said you had an old century board and patch panel. I would check all the connections from the board to the dimmer to the patch to the light, remembering safety.

    You aren't repatching lights during the show are you? If this is the case is someone doing it at the wrong time?

    Also it sounds dumb but have you double checked the cues to make sure this light is in the right place.

    There's a few ideas to start with but if you post more details of exactly what equipment you are using someone might have had the same problem.
     
  3. Footer

    Footer Senior Team Senior Team Premium Member

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    9 times out of 10 with symptoms like that its a bad socket or pigtail. Change out the basecap and see if it stays up.
     
  4. fosstech

    fosstech Active Member

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    What Footer said ;)

    It's most likely that something is heating up and losing contact.

    Check the base, it probably is all carboned up from badly seated lamps and/or old age. Only real fix is to replace the base. Did you notice any evidence of arcing on the pins (melted spots, black deposits, etc.) when you pulled the "blown" lamp? If so, your lamp base is probably shot.

    Take a Gam Check or similar device and plug the instrument into it. Wiggle the lamp around in its base and make sure it is always completing the circuit.

    The fact that it worked on another lamp rules out a circuit breaker or fuse. Dimmers seldom do this, so I wouldn't go directly to the dimmer. When dimmers fail they usually fail either stuck on or stuck off. But if all else fails, you might as well check them out.
     
  5. zac850

    zac850 Well-Known Member

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    Though it could be a problem with the dimmer. Dimmer heats up, and can't regulate heat it could fail.

    I had an issue a year or so ago when one of my smartpacks lost its fan, so it would heat up, over-temp, shut off, cool off, turn on, and so on. It was rather annoying during that show when a third of the rig randomly turned on and off....

    It is unlikely that it is this, of course, since your only loosing one fixture.

    How is power to this fixture run? It could be a loose connection in one of the cables that is getting kinked for some reason. It could also be an issue with a contact in the base of the fixture. It could also be a million other things, sadly.

    It could also be a programing error, for that matter.

    Try putting a different fixture in its place, if the problem ends then your issue is with the fixture, in which case you (or someone who knows what their doing in there) should open the cap up and see what the problem is. If the problem persists, then its time to check out the system.

    Good luck
    Zac
     
  6. gabe

    gabe Member

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    Thanks for all the replies. I can rule out a programming error because it's not a memory board, old school two scene preset all the way :p. I am going to try to replace the fixture tonight when I arrive for the show. And I definately can't rule out a system-wide error as our entire system is falling apart and we're in the "lets get through this show and then talk," phase.
     
  7. SHARYNF

    SHARYNF Well-Known Member

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    I would GUESS that it is a heat generated problem probably with the socket. It could be a heat problem with that dimmer channel, you could change the instrument to another channel. Lastly it could be something in the board that sends a mis signal to the dimmer. You could of course test this by swapping addresses for the dimmer

    Sharyn
     
  8. Schniapereli

    Schniapereli Active Member

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    We have had that problem before. The light could be turned on once after you have fiddled with it. (we had really old Altman ellipsoidals)

    Try just taking the level down to 5% or 3% so the fixture doesn't go entirely off, but is low enough that the audience doesn't notice. Depending on the show, that could be a good or bad solution.
     
  9. Footer

    Footer Senior Team Senior Team Premium Member

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    Not the best idea. When you have a fixture that only works if you touch it the only reason it is working is due to arcing inside the lamp base. When you have it at that low of a level it is arcing even more. This is very dangerous and you run the risk of destroying your fixture more then it allready is and making a before good lamp useless. Buy a new base for your fixtures (I like the C3A supersockets from Osram). They run about 15 bux a piece (about the same as a new lamp) and hold up very well.
     
  10. jbsue

    jbsue Member

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    Had the same problem myself.
    Try dipping the lamp base in BRASSO and then work it around it the socket.
    If this works, it means the socket contacts have burned off or wore off the silver or gold plating and have tarnished and don't conduct electricity anymore.
    I like the Ushio C3A base for med-2 pin lamps. Drill out the rivets, use the leads and porcelain in Source Fours.
     
  11. mackierox93

    mackierox93 Member

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    pleas egive more info about the problem
     
  12. LightingGuruJmac

    LightingGuruJmac Member

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    OK, I know how you feel. This has happened to me many times. It actualy happened to me in an ETC Source Four Revolution. Everytime, the light would come on the first time, and then go out and ould have to be re-set. It was a short in the wires that connected the lamp to the ficxture, that is why re-setting it helped. So it is more than likly a short in the wire that only happend after so long of a burn. Hope that helps!
     
  13. Diarmuid

    Diarmuid Active Member

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    Is it by any chance a fresnel?? because some of them, (in particular Selecon 1200 Compact) have a safety switch which cuts power to the lamp, when the lamp housing is open.. admittedly this is kinda unnessecary, because before you start changing the lamp or anything like that, you should always unplug it, or physically trip it at the dimmers etc. Anyway, sometimes this switch gets bent after the fresnel being used a lot, and as such even when the lamp housing is closed, the switch contact is only intermittent. Im not entirely sure on the best way to fix this, but I think you can either bend the contact back, to make it closer to the housing door, or just pack in a bit of tape...
    (some other fixtures may have this style of switch, but I have only come across them in fresnels)
    Hopefully thats some help.

    Diarmuid
     

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