LCD making noise

Discussion in 'OT Technology' started by Zak8022, May 3, 2007.

  1. Zak8022

    Zak8022 New Member

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    Is it bad that my LCD is making noise? It sounds like a CRT thats dying...

    Its sort of a very soft, quasi-high pitched noise. Very consistent... stops when i turn the panel off... starts right back up when i turn it on.

    Yes, its an old panel, but i'm not sure i can talk my boss into a new one (its a secondary monitor anyways). Is this a sign its dying?
     
  2. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Is it a Dell?
     
  3. Zak8022

    Zak8022 New Member

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    No... Viewsonic... old. VG500 according to the back. Its a shitty 15" i think... i've never bothered measuring it... its max resoltion is 1024x768 :thumbsdown:
     
  4. Slid.

    Slid. I'm a guy.

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    We had an LCD in the office start making a buzzing sound. A few weaks later it started smoking (electrical fire). So I'd keep an eye on it and not leave it on (or in standby) while you're not there.
     
  5. Zak8022

    Zak8022 New Member

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    :noes::noes:

    Damn, i want an excuse for a new monitor... but not that badly!
     
  6. deusexaethera

    deusexaethera OT Supporter

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    It's probably the mercury halide fluorescent backlight that's buzzing. They do wear out over time.
     
  7. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Oh, ok.
    I'd heard of a Dell that was doing that and they were replacing them, is why I asked.
     
  8. dorkultra

    dorkultra OT's resident crohns dude OT Supporter

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    my cousin has a westinghouse lcd that he bought new as an open box item (so it wasn't really new, just newer)

    it makes a high pitch noise sometimes, it really bothers me, but he can't hear it because he's older so it doesn't bother him
     
  9. Zak8022

    Zak8022 New Member

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    I don't understand your first sentence... so i'm going to pretend i know what you're talking about.

    The second sentence i get though... so thats a plus!
     
  10. Zak8022

    Zak8022 New Member

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    I guess its time to start working my boss for a new monitor too... yesterday i asked for a NAS, today it'll be a monitor. :o
     
  11. deusexaethera

    deusexaethera OT Supporter

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    Fluorescent bulbs are used to light the back of most LCD screens. The LCDs themselves only act as filters for that light -- LCDs don't generate their own light like old-style monitors do.

    The part about the bulb being filled with mercury halide gas isn't significant except that it's the same stuff used in most every fluorescent bulb you've ever seen.
     
  12. deusexaethera

    deusexaethera OT Supporter

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    I buy my own office equipment. The downside is it costs me money, but the upside is that nobody can tell me I can't have it and I can take it with me when I leave.
     
  13. Zak8022

    Zak8022 New Member

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    I am very close to being like this. I already buy my own peripherals myself... i just havent brought myself to buying the bigger things.
     
  14. emorphien

    emorphien New Member

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    How loud is it? I've had an NEC 1980SX that's had a slight buzz from the backlight since day one. It still works almost 3.5 years later and is still one of the best LCDs I've seen/used. I am very sensitive to high frequency noises though, so what I hear and worries me may be inaudible to others. So yeah, how loud is it?

    Most every kind of backlight i've seen buzzes, watches, cell phones, you name it and they all buzz.
     
  15. mobbarley

    mobbarley Active Member

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    no, it would be the inverter(s) for the backlight.
     
  16. deusexaethera

    deusexaethera OT Supporter

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    You've never heard an old fluorescent bulb buzz? You must not work in an office.

    Anyway, without actually opening up an LCD panel to look, I doubt they have inverters to run the backlight because fluorescent bulbs don't actually like alternating current -- they just get stuck with it when they're used in light fixtures. Since LCDs have AC=>DC power bricks, I can't imagine why they would convert that DC power back into AC just to run one part that doesn't even work well with AC. Besides, wouldn't AC power make the backlight flicker like an old CRT monitor? I know for damn sure that mine doesn't do that.
     
  17. EvilSS

    EvilSS New Member

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    LCDs are usually backlit with Cold Cathode Fluorescent tubes (CCFL) and they do use inverters. It's quite possible for one of them to begin to buzz or whine (been there, done that, finally killed the stupid thing).

    Another possibility this: does the monitor have built in speakers? I have one LCD that I had to turn the volume all the way down on the speakers (even though I didn't even use them) because they developed a humm over time.
     
  18. mobbarley

    mobbarley Active Member

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    :mamoru:

    you have no idea what you are talking about.
     
  19. Zak8022

    Zak8022 New Member

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    yea, it does have built-in speakers, though
    I never use them.

    it seems to do it when certains screens are eing displayed, tho I haven't been able to figure out what kind of output causes the noise.

    I'm not too woried about it since it is an oldas monitor, and shitty, and has more than outlived its usefulness.
     
  20. deusexaethera

    deusexaethera OT Supporter

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    As noted in the very post you quoted, yes. But I AM certain that fluorescent bulbs perform better on DC power than AC power.
     
  21. EvilSS

    EvilSS New Member

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    Deus/mob: Keep in mind that CCFL's are not traditional fluorescent tubes, they work more like neon lamps and require a high voltage, low frequency (usually under 60 hz) to operate.

    Also, most fluorescent lamps are never run from DC power because it complicates their operation. The unit would have to invert the power every so often to prevent mercury accumulation on the cathode side of the tube. To prevent flicker they use electronic ballasts that increase the frequency to move the flicker up above perception (most newer compact fluorescent bulbs use these, as do the more expensive (i.e. not the super cheap) ceiling fixtures). Since the bulbs flicker at twice the input frequency, they don't have to switch it up all that high.

    And thus ends the lightbulb lessons for today.
     
  22. deusexaethera

    deusexaethera OT Supporter

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    Huh. I've never heard of that "mercury accumulation problem" before.

    Learn something new every day.
     
  23. Slid.

    Slid. I'm a guy.

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    WTF, did I really use "weaks" instead of "weeks?"

    :squint:
     

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