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Mirror Ball Rotator

Discussion in 'Lighting and Electrics' started by adambattey, Jun 22, 2009.

  1. adambattey

    adambattey Member

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    Hey Guys,

    A few weeks ago I gave a mirrorball rotator to a collegue so that he could change the plug on it to allow me to have it plugged into our lighting rig and the motor turned on and off via the control desk. Today he gave it me back and I have plugged it in - it rotates just fine....but it won't stop! Even if I turn everything down, hit the B/O switch - and even turn the desk off - it quite contently keeps on spinning.

    Any ideas on how (or if) i can stop this? I don't want it to be rotating through out the the days never mind the shows it is going to be used it as it will distract the audience's eyes.

    Hope you are all well,

    Adam
     
  2. Erwin

    Erwin Member

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    Well,

    At the risk of stating the obvious, that means that your rotater is getting power regardless of what your control desk is doing. So, is it plugged into a dimmer? Is your dimmer overridden by the control card in the rack?

    If it is in a dimmer, just turning off the lighting board doesn't clear all the dmx data from the dimmers. Did he/you put a profile on the dimmer so that it is always on? If so, re profile it so that it is full at 1% not full all the time. If you turn your dimmers off does it stop?

    Simply changing the plug shouldn't cause such an issue, so a little more info would help.
     
  3. adambattey

    adambattey Member

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    Ha ha, I had kindo figured that one out! lol! But someone needed to say it!


    It is indeed plugged into the dimmer. I didn't have chance before coming home to check whether turning off the dimmers would stop it so i just unplugged it. I also haven't done anything in terms of re-profiling it [partially due to time and partially me wanting to see what you guys had to say before i started barking up completely the wrong tree]. I knew that i wouldn't be a problem with the changing of the plug as i have seen it done and done it in the past. I will give the re-profiling a go tomorrow and see what happens. [it is fairly straight forward right..? ha ha! I'm on my own on this on and flying slightly blind if you couldn't tell! ha ha ha!]

    Cheers,

    Adam
     
  4. rochem

    rochem Well-Known Member

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    I'd be cautious about using a mirror ball motor, or any motor for that matter, on a dimmer, unless of course it was designed to run on a dimmer. I've done a number of shows using a spinning mirror ball, and for those I just used a standard wall outlet and ran it through a switch located at the SM's console. Depending on how powerful the motor is, the dimmer may still be sending a small amount of power, just enough to still move the motor.
     
  5. epimetheus

    epimetheus Well-Known Member

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    I second this. Depending on what dimmers you have, the motor may be too small a load or the wrong type of load (inductive verses resistive) for the dimmer output to function properly. If you want to control it via DMX correctly, then you should have it plugged into a relay module.
     
  6. VanJohnson112

    VanJohnson112 Member

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    Horse Power and Wattage are huge differences with dimming. I agree with going with a relay for an application like this.
     
  7. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Take it off the dimmer for the safety of the motor. No need for anything fancy. Just run an extension cord off stage along the batten and have a technician plug it in when it's time to go.
     
  8. kiwitechgirl

    kiwitechgirl Well-Known Member

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    If you really, really want to run it off a dimmer (taking into account all the advice you've already been given!) then put a dummy load on the dimmer channel as well - a spare lighting unit, plugged into the same circuit, put somewhere out of the way where it isn't going to spill light onto the stage or into the wings. It'll stop the problem - even when a dimmer is at 0% there's a small current still flowing and it's enough to make the rotator turn. A dummy load will "absorb" this current and stop the rotator :)
     
  9. Van

    Van CBMod CB Mods Premium Member

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    Good Idea from Kiwitechgirl. A dummy load, or Ghost Load could help. Now without sounding too pedantic... are you sure the Motor was still rotating? Mirror ball motors have a clutch which allows the ball to turn after the motor has stopped thus burning off inertia, and protecting the motors gearing from damage. The reason I bring this up is I once thought the same thing, that I had a dimmer that was mysteriously staying on, ' cause the ball kept spinning after I turned off the channel. After close inspection I found it was just "coasting" to a stop. The larger diameter of a ball the more rotational momentum the longer it takes to stop.
     
  10. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    kiwitechgirl, had this thread remained in the Question of the Day, you would have won, (in my experience). See the wiki entry, ghost load.

    See also these threads:
    http://www.controlbooth.com/forums/lighting/2210-miiror-ball-motor-dimmer-pack.html
    http://www.controlbooth.com/forums/lighting/11561-constant-power-dimmer-circuits.html
    http://www.controlbooth.com/forums/special-f-x/9547-dimming-motors.html

    Now, has anyone ever had a rotator that, every time power was cycled, it spun in the opposite direction? I once hung ten or so for a party in a ballroom, and I swear this was happening. Naturally we were on a time crunch so I couldn't prove it, but it was odd to see mirror balls spinning in two directions. (I then discovered the turntable in my microwave spins the opposite direction each time. Freaky!)
     
    Last edited: Jun 22, 2009
  11. ship

    ship Senior Team Emeritus Premium Member

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    Very good help - well done in all the concepts covered in what might be = perhaps a FAQ in the making on such a thing. Doubt in re-plugging switching hot for neutral would reverse the motor as not posted.

    Still in any such post I would start with brand and type of mirror ball motor, size of mirror ball run, and dimmer type controlled off of in that some need a relay, others can be fine in switch mode. This just as some are fine with dimming if not DMX controlled for speed which is its own ball of wax.

    After that... Adaptors, Adaptors, Adaptors. Your initial question was in asking about someone else re-wiring your gear and questioning potentially him doing so. If this is going to be a frequent thing, this borrowing of your gear, and or something you might reasonably expect such as converting stage to Edison than you should have say 18" adaptors pre-wired for such a purpose.

    Rule of thumb on making adaptors is never jump to more than one amperage rating: if using a 15A plug and 20A is available you cannot jump to 30A. This as with requirements of single conductor feeding into multi-conductor plugs not allowed without special work, and overall say you cannot feed even a 60A female from a 400A service if that 400A service is not fused or breakered down by way of the service panel or your adaptor including circuit protection to cover for maximum rated amperage of the adaptor. Also voltage concerns = even if your say moving light is auto sensing for voltage, really bad Karma to make a even 15A 250V adaptor to 15A 125V adaptor. Such a thing should never exist due to the likely possibility for someone to plug something not auto sensing or switched in voltage into 208V power. Instead if really necessary to go 208V to 125V and while pain in the rear most often heard, it is more safe to say go 208V to stage pin that's dual voltage rated and attach that adaptor as needed to a stage to Edison or in general 125V adaptor. Yes, can still blow up a few zenior diodes in the fixture - this if not circuit board in going one way or another in doing so but by way of what adaptors you provide it was not by way of you in doing something that is not a good thing to exist.

    General rules, 18" adaptor is most useful and only one step up or down in amperage - normally within five amps and after that fuse or breaker protection between larger amperage power supply and outlet or ok if larger connector as long as fused or breakered to assure it's going to trip before cable or plug fails. No jumps between voltages unless those plugs adapted to are rated for dual voltage.

    Further thoughts, if making say a three phase to single or dual phase adaptor, marking which phases are tapped is very important in noting on the adaptor so as to balance the load or not to draw too much off any one phase.
     
    Last edited: Jun 22, 2009
  12. Van

    Van CBMod CB Mods Premium Member

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    YES ! Freaked me out the first time I saw it.
    Making Nachos at 2 am I thougt I was crazy too, sure enough my microwave spins in different directions too.
     
  13. NickJones

    NickJones Active Member

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    Mmmm Nachos..... (Now I'm hungry)
    Could the reason it turned in a different direction be because the person who put your plugs on switched the posotive and negative around? Would this matter on a motor? Just general pondering.
    Nick
     
  14. adude23

    adude23 Active Member

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    In response to the first question it sounds to me like your dimmers are on 'pre-heat' I.E. sending out just enough power to warm the lamps of your conventional fixtures up!
    and about the mirror balls spinning in different direction I've always had that and never have really found out why?....hmmm!
     
  15. David Ashton

    David Ashton Active Member

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    A synchronous motor will spin in the direction of the first half cycle of power it sees, so it is entirely random which way it spins.The leakage through the dimmer will drive a small motor or give you a shock, even when at 0.Many small motors have a small spring to only allow it to go one way.A really good toy is a variable speed and direction mirror ball motor.
     
  16. 00AVD

    00AVD Active Member

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    Induction motors can do this. Some have an extra part (shorted turn?) to force them to always start in the same direction. As you've seen, the unknown starting direction can really play havoc when you've got more than one! :lol:
     
  17. kiwitechgirl

    kiwitechgirl Well-Known Member

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    I second this! We've got one in our tech store, built by a tech who used to work in the building, and it gets used frequently. I've also noticed the changing-direction motors - dunno about my microwave though, I'll have to check it now!
     
  18. Van

    Van CBMod CB Mods Premium Member

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    Any excuse to make Nachos ! :twisted:
     
  19. NickJones

    NickJones Active Member

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    Amen.
    The motor thing is interesting, so how come when I last used one the ball spun in the same direction each time? Just luck that the 20 times I used it (and was concentrating) it span in one direction, or does this only happen to a few types of motor? Presumably this is so otherwise the "Make your Own Electric Motor Boat" kit I did as a Kid would have randomly gone forwards & backwards, depending on when I turned it on? And if all your motors are on the same channel presumably they would all spin in the same direction as the all received power at (roughly) the same time?
    Nick
     
  20. dramatech

    dramatech Well-Known Member

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    Nick, you are confusing AC and DC motors. That model boat you built as a kid uses a DC (battery driven) motor. DC motors will always turn the same direction based on their connections. A DC motor usually will have a red and a black wire. The red would usually be connected to the positive and the black to negative. If those wire connections are reversed, then the motor will turn the opposite direction. AC motors could tun either direction based on the half cycle start, but most of them are made with a spring or some sort of device that will make them always start in the same direction.
    The microwave issue, is designed to reverse directions every other use. The reason for this, is that if you are microwaving some sort of liquid and want it to mix evenly, when you stop the microwave to check on how hot it is, if you run it another cycle with the same food product, it will give it a better mix and better heat distribution.
    One of the most problematic occurances in the theatre, is people understanding the differance between a mirrorball motor and a twinspin motor. The Twinspin (dual gobo rotator) is a DC motor, that receives it's power from a small AC to DC converter. When a dimmer changes the AC voltage on the primary of the tranformer in that converter or power supply, the secondary voltage of the transformer is also changed proportionately and then rectified and filtered into DC, and therefore the speed of the twinspin changes, with a change of the dimmer setting. The mirrorball motor is usually an AC motor, and the speed is controlled by the line or mains frequency, 60hz in the US/Canada and 50hz in most of the rest of the civilized world. Therefore That mirror is going to spin a bit slower in Australia, New Zealand, England and any other country that our CB memebers have 50hz.
    I have argued until I am blue in the face with many of our lighting designers that you cannot change the speed of a mirror ball motor by dimming the circuit it is on. I am of course wrong in their eyes right up until the mirror motor dies. I have three dead motors to prove it. When using a mirror ball motor on a dimmer, set the profile for non-dim. (that is a 6 on ETC Express/Expression)
     

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