Connect with us

Monitor makes loud buzzing sound when UPS is on Battery

Discussion in 'General Electronics' started by zack, Jun 29, 2003.

  1. zack

    zack Guest

    I'm using an APC BR1500 as a battery backup unit. Whenever I disconnect
    it from the AC source and it switches to battery mode, my monitor makes
    a loud buzzing sound, which is similar to the sound coming from the UPS,
    but louder.

    I'm assuming this is because when on battery mode, it does not output a
    pure sine wave, but a "stepped sine wave". The noise doesn't really
    bother me, since it only happens on a power outage, but I am worried
    that this could damage my monitor. I am using an SGI GDM-5411 monitor,
    which i'm told is the same electronically as a Sony GDM-F500R, which is
    more common.

    Should I be worried about this buzzing noise ? It doesn't affect the
    image at all. The image is still crisp, clear, and bright, with no
    distortions while using the battery.
     
  2. Doesn't sound all that healthy to me. I wouldn't run it for any longer
    than it takes to shut-down in an orderly manner while waiting for the
    mains to return.
     
  3. in message
    Unless it was extremely loud, it wouldn't bother me. The APC BR1500 is
    designed for computer loads. Although stepped-sine/square waves usually
    cause higher peak currents to occur in bridge rectifiers and capacitors, I
    can't see it adversly affecting the switch mode power supplies found in
    monitors and other computer equipment in any serious way (at least when used
    for only minutes at a time). Although I can't recommend doing so, if you
    opened your monitor up and removed any less-than-critically-important
    magnetic components (like a lossy ferrite core commonly found wrapped around
    the mains input wires), you would probably decrease the audible buzz.

    Howard Henry Schlunder
     
  4. AC/DCdude17

    AC/DCdude17 Guest

    X-No-Archive: Yes
    This might make it more psychologically pleasing, but it aggrevates the
    problem. The front-end ferrite core inductors found inside the monitor power
    supply minimizes the amount of high frequency interference traveling into power
    line and it's also a reactor. When you take out the reactors, you further
    decrease Irise time increasing peak current especially if the UPS is large and
    has a low source impedance.
     
  5. zack

    zack Guest


    I think what I might do is just plug the monitor into a non-battery
    powered outlet, and if the electricity does happen to go out while I am
    at the computer, I can plug it into the battery powered outlet for a
    short period of time, giving me time to shut down. Because my computer
    might be off one day while I am not home, and since it makes the same
    noise when the monitor is off, it would do this for at least 4 hours.

    By the way, on the bottom of this device, it says: "The output of this
    device is not sinusoidal. It has a total harmonic distortion of 67% and
    a maximum single harmonic of 40%." What does that 40% value mean? I now
    understand why they don't advertise this in the specifications on their
    web site.
     
  6. zack

    zack Guest

    I think what I might do is just plug the monitor into a non-battery
    powered outlet, and if the electricity does happen to go out while I am
    at the computer, I can plug it into the battery powered outlet for a
    short period of time, giving me time to shut down. Because my computer
    might be off one day while I am not home, and since it makes the same
    noise when the monitor is off, it would do this for at least 4 hours.

    By the way, on the bottom of this device, it says: "The output of this
    device is not sinusoidal. It has a total harmonic distortion of 67% and
    a maximum single harmonic of 40%." What does that 40% value mean? I now
    understand why they don't advertise this in the specifications on their
    web site.
     
  7. Nico Coesel

    Nico Coesel Guest

    That's not going to work. The UPS will overload either because of the
    rush-in current of the monitor or the degauss coil. If you want to
    have an image when the power goes out, disable power savings on the
    monitor and power if from an UPS output.
     
  8. The RF filters on the monitor's power input are buzzing. I wouldn't
    worry about it.
     
  9. Rowbotth

    Rowbotth Guest

    So you believe that the DC - AC Conversion within the UPS is giving a
    waveform that is doing no damage to the monitor?

    I'd think it would be best to get off the computer during a storm that
    shuts off the power, personally. (The UPS shoulld be used to shut down
    in an orderly fashion so nothing is lost, but that is all.)

    Or what?

    HR.
     
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-