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Projector turning itself on - flourescent light interferance

Discussion in 'Projectors, Screens & Video Processors' started by Matinee, Jan 21, 2003.

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  1. Matinee

    Matinee
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    Some while ago I mentioned that my projector was spontaneously turning itself on, and pondered what it was, fingering flourescent lights as one possible candidate.

    Since then I've been switching it off at the wall after use. However, I've had a lot of problems switching it into standby - it took repeated presses before it took effect.

    I fingered the lights as a possible problem again.

    Over the course of the last week, I've had a play - it /is/ the lights. If the lights are off, the projector goes into standby instantly, if they're on it takes many presses.

    A browse around the web reveals this

    which includes the key quote :

    'The high carrier frequency means that it can easily filter out noise from tungsten lights and the TV tube (100Hz). However, flourescent lights are often driven by electronic circuits which means they flicker at several kHz instead of 50/60Hz. Therefore their infra-red noise may be at a similar frequency to the handset carrier.'

    And a related item

    'When you are finished using the projector, turn if off with the Extron switch or the projector remote. Be sure that it stays off; we have occasionally observed this projector turning itself back on; this is caused by noise frequencies from flourescent lights. Therefore, we've mounted a shield around thesensor to avoid this phenomena and the problem is considered resolved.'

    Building a shield sounds far too easy to me however, and thus I am devising a Cunning Plan involving an extremely long serial lead and custom software on the HTPC...

    PK
     
  2. GagHalfrunt

    GagHalfrunt
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    Wouldn't it be easier to change the light?
    :cool:
     
  3. Blighty_Boy

    Blighty_Boy
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    I have the same problem with my cable digi box I have a 100W equivalent energy saver in my living room and I quite simply cant use my digi box whilst it is warming up when its at full brightness its fine it also has the tendancy to turn my PJ on randomly
     
  4. Matinee

    Matinee
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    What's your projector Blighty?

    My lightbulb is an ES 50W equivalent (11W) energy saver, that fits in a low profile light fitting (otherwise the fitting would get in the way of the projector).

    My cunning plan is to tell the projector to ignore any on and off signals, and then control on/off and other functions via the serial port - it is theoretically possible to do this programatically.

    PK
     
  5. Blighty_Boy

    Blighty_Boy
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    its a Barco Data 800 it doesnt do it often enuf for me to worry about it :)
     
  6. Roland @ B4

    Roland @ B4
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    This is fairly common with Barco's they use a PPM (phase pulse modulation) which makes it a common problem with dimming flourecents.
    To check just look at the RCU light on the contoller board if it's on then some form of infra red is being picked.
    Those pyramid relay things cause real problems too.
    I've never heard of one switching the projector off but changing chanels and the processor frezzing is not unknown.
    1200's and 800's were very prone to IR interferance.
     
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