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Automated Fixtures ML Fixing Help

Discussion in 'Lighting and Electrics' started by Charc, Apr 16, 2009.

  1. Charc

    Charc Well-Known Member

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    I am trying to get a pair of Lyte Quest Motorhead DJ style MLs (aprox 10yrs old), in good working order for an upcoming production.

    I've resolved a number of my issues, but I am left with one major one.

    I have a gobo wheel which will not respond to commands. Not sure if it is spinning at all, but I believe it is not.

    Not sure what the issue would be, straight up dead motor? If that's the case, I am inclined to think the part would not be kicking around anymore.

    Should I be checking for a connection that may be loose or something? I will have to entirely breakdown the unit early next week to look at the issue.
     
    Last edited: Apr 16, 2009
  2. abbyt

    abbyt Member

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    Occupation:
    Field Service Engineer
    Location:
    Greater Cincinnati, Ohio area, United States
    Not knowing anything at all about the unit itself...here are a few stabs in the dark...

    This is assuming that the problem lies in the fixture and is not a console/patch issue...

    1) Driver chip
    2) Bad/pinched wiring or connectors in the motor circuit
    3) Bad Motor
    4) Bad bearings/gears/belt
    5) Physical object impeding movement (a loose screw jammed somewhere?)
    6) Bad PCB components somewhere (other than aforementioned driver chip)
    7) Some strange mode that disables the gobo wheel


    What kind of motor and gearing does the gobo assembly have? Stepper motor or linear actuator (I am assuming the former...)

    Is the gobo wheel mounted straight to the motor shaft, or is there another piece of hardware involved? (belt, gear, bearing, etc)?

    Is there a sensor system that will give you errors if it senses them? (optical or magnetic sensors?)

    Is the wheel stuck in the open position, one particular gobo frame, or some random place in between?

    Does the gobo wheel move or even jitter? Even ever-so-slightly?

    -Abby
    Posted via Mobile Device
     
  3. Charc

    Charc Well-Known Member

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    I much appreciate the reply. This light is of low quality, so I'm abandoning the idea about sensors.

    I can manually actuate the gobo wheel. As for the motor, you are correct in assuming it is a stepper motor, in axis with the gobo wheel, but it uses another gear to spin the wheel.

    When I manually reposition the wheel, I do in fact see the motor's gear turning. It appears to be fairly tight there. I did not feel any resistance in terms of debris in the way.

    There is not an apparent whining noise when I pull up the gobo wheel on the board.

    I've checked the fixture profile on a known good.


    When I pull it apart I am going to hope for a pulled connection, and I'll keep my eye out, but I'm really looking for the motor part numbers.
     
  4. photoatdv

    photoatdv Active Member

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    Even though it's a cheapo light, I would think it would have to have some type of sensor on it (even though it may not report errors) becuase it uses that to home.

    Try this... (with the fixture off) pick a gobo and line it up so that one is in the optical path. Put the fixture back together and turn it on. Is it still on the gobo you had it on or some other random place? That will tell you if it's moving at all.

    Or, get somebody qualified to work on it live to help you. I know one time when we were troubleshooting a color wheel we did that (can't remember much about what setting/ precautions/ ect we did-- I'm sure there are some).
     
  5. abbyt

    abbyt Member

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    Occupation:
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    Greater Cincinnati, Ohio area, United States
    Just a quick bit of clarification...attributes, in general, actually do not have to have sensors to home. Though it makes sense that a sensor is necessary to home an attribute, that isn't the case in all instances.

    In some cases, there is no sensor present, and the attribute has a hard (mechanical) stop. (For example, shutters on a MAC500...)

    Further along these lines, there may not even be a mechanical stop at all...the attribute may just travel left or right (in or out, up or down, etc) depending on the signal it receives, never having a stopping, or "home" position at all...

    -Abby
     
  6. Charc

    Charc Well-Known Member

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    All attributes home mechanically, as aforementioned. Every value tries to reset until it hits a mechanical stop, in most cases, a screw is positioned to stop the attribute.

    In terms of qualified, we were under the assumption the unit was beyond repair. So certainly paying to fix this unit would be a mistake. I will tinker as best as I can. I may pay out of pocket for a replacement motor, if they're available.
     
  7. Charc

    Charc Well-Known Member

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    The body of the unit is riveted together, so entire disassembly is out of the question.

    I did notice that when manually manipulated the GOBO vs COLOR wheel, there is a difference in their feel. The color wheel is easy to rotate, little resistance. The GOBO wheel takes considerably more force to turn, feels like some sort of obstruction.

    Does this resistance indicate a failed motor, or perhaps debris? Where would this obstruction take place, inside the motor housing, or perhaps some where between the gears?

    Any thoughts here?
     
  8. Sony

    Sony Active Member

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    Occupation:
    Freelance Electrician/Rigger
    Location:
    Massachusetts
    It could be ether, if some dirt or sand got wedged in the bearings it could cause that. More likely is that the motor failed, if the motors bearings failed then it could seize up and be hard to turn or the rotor in the motor could be rubbing against the stator, causing friction. Ether way would cause resistance, the easy way to tell would be to remove the motor and try and turn the motor yourself by hand. If there is any play in the shaft or resistance then you most likely have a dead motor. If not and the gobo wheel is hard to turn without the motor attached then you have a bad bearing on your gobo wheel. It could even be both since if the bearing on the wheel died and prevented the motor for turning when asked, it could cause the motor to burn out.

    Another thing to check would be is the motor even getting electricity? If the motor isn't getting power then obviously it wont turn.
     

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