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LG Monitor makes a high pitch noise

Discussion in 'Electronic Repair' started by [email protected], Aug 7, 2004.

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  1. Guest

    I have had my LG 17" Flatron T710BH CRT monitor for three weeks now
    and it makes a high picture noise. The noise is intermittent and
    normally occurs about 30-40 mins from been switched on from cold.

    I called LG tech support two days ago and explained this to them, they
    said that it was the components warming up and if the sound doesnt
    come back there is nothing to worry about. As the sound now starts to
    come back occasionally now and last longer i don't think that it is
    the components warming up that is causing this.

    I will be calling LG back about this and ask for a new monitor but i
    was just wondering if any other users have experienced any problems
    with this model or any other LG crt monitor becase i don't want to get
    another monitor only to find it does the same thing or sounds worse
    just in case it is a design fault, but apart from this i genrally like
    the monitor but would like some advice.

    Thanks in advance

    du.
     
  2. Jerry G.

    Jerry G. Guest

    There are a number of things that can be the cause, two, of which are
    harmless but annoying.

    It is possible that a bypass cap(s) of some type is failing in the power
    supply, or the HV generator, or the Horiz scan circuits. This can lead to a
    serious fault.

    The ones that are harmless but annoying is that there may be a winding, or a
    few of them, in one of the reactive components used in these circuits that
    is sort of loose and is resonating. This can be in one of the transformers,
    inductors, or the deflection yoke. It can also be a metal shield or metal
    part that is resonating from the magnetic field emission of a reactive
    component that is close by.

    This effect can be occurring with temperature change, since there is some
    expansion and contraction of parts, and assemblies with heat. This may be in
    a very small fraction of size, but enough to make something to be reactive
    to a particular type of resonance.

    The bottom line is that it should be properly checked during the warranty
    period. These repairs can be fairly costly, especially for the time after
    the warranty is over.

    Samsung monitors are generally very good monitors. They are usually very
    reliable, with very few failures during their expected life span.

    --

    Jerry G.
    ==========================


    I have had my LG 17" Flatron T710BH CRT monitor for three weeks now
    and it makes a high picture noise. The noise is intermittent and
    normally occurs about 30-40 mins from been switched on from cold.

    I called LG tech support two days ago and explained this to them, they
    said that it was the components warming up and if the sound doesnt
    come back there is nothing to worry about. As the sound now starts to
    come back occasionally now and last longer i don't think that it is
    the components warming up that is causing this.

    I will be calling LG back about this and ask for a new monitor but i
    was just wondering if any other users have experienced any problems
    with this model or any other LG crt monitor becase i don't want to get
    another monitor only to find it does the same thing or sounds worse
    just in case it is a design fault, but apart from this i genrally like
    the monitor but would like some advice.

    Thanks in advance

    du.
     
  3. Guest

    Thanks for the quick reply.

    I have had the monitor running for a few hours and the sound has come
    back. I have just been adjusting refresh rates and when i lower the
    refresh rate to 72hz from 75hz the sound seems to disappear, when i
    changed the the refresh rate back to 75hz the sound returned again. I
    also put the refresh rate up to 85hz and the sound went then once more
    put the refresh rate back to 75hz and once more the sound returned all
    these refresh rates are using a resolution of 800x600.

    What i was wondering is it possible that my graphics card is at fault?
    it's not a new card in fact it is a ' AGP ATi xpert 98' card that is
    linked to a separate voodoo2 3d graphics card. The voodoo2 card is
    connected to the ati card by a cable then the monitor connects to the
    ati card.

    Thanks again

    du
     
  4. Phil Durgin

    Phil Durgin Guest

    Download the monitor.inf file from www.lgservice.com and see if that takes
    care of the problem.

    Phil
     
  5. Jerry G.

    Jerry G. Guest

    I doubt very much it is the display card! Changing the refresh or scan
    rates, changes the load on the supply and scan circuits. The noise you hear
    has to do with resonance, and therefore there will be a window of
    specification where the sound will occur. Ideally, these circuits should
    work near resonance to be best in their efficiency.

    Just for the fun of it, when the monitor makes the noise, try lifting it a
    bit, or putting some pressure on it to tilt it. Sometimes if it is something
    mechanically resonating, you can actually change how it will sound. This
    will prove that the problem is more mechanical than electronic.

    I used to have a Viewsonic monitor that did a resonance from time to time. I
    was too lazy to open it up and find the problem. I would just press down a
    little on it, and the noise would stop. This was from something mechanically
    resonating.

    --

    Jerry G. GLG
    ==========================


    Thanks for the quick reply.

    I have had the monitor running for a few hours and the sound has come
    back. I have just been adjusting refresh rates and when i lower the
    refresh rate to 72hz from 75hz the sound seems to disappear, when i
    changed the the refresh rate back to 75hz the sound returned again. I
    also put the refresh rate up to 85hz and the sound went then once more
    put the refresh rate back to 75hz and once more the sound returned all
    these refresh rates are using a resolution of 800x600.

    What i was wondering is it possible that my graphics card is at fault?
    it's not a new card in fact it is a ' AGP ATi xpert 98' card that is
    linked to a separate voodoo2 3d graphics card. The voodoo2 card is
    connected to the ati card by a cable then the monitor connects to the
    ati card.

    Thanks again

    du
     
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