Connect with us

Monitor Hissing At Me!

Discussion in 'Electronic Repair' started by Tim H., Jan 21, 2004.

Scroll to continue with content
  1. Tim H.

    Tim H. Guest

    Hello,

    My dad's monitor decided to call it quits on him w/out any warning. It's a
    no-name monitor with a Samsung tube and a ProView microcontroller. He did
    say he heard a paper-rustling type sound before it went. I can only imagine
    it was the flyback doing that. I go to turn it on and I just hear the power
    supply cycling and the green LED on the front is flickering. I do a little
    digging, check for obvious shorts (HOT, caps, etc) and discover that the HOT
    is shorted. I yank out of the circuit and test it off-board -- she's dead.
    Just for kicks, I measure Vec of the HOT while it was out of circuit and I
    measured 62V.

    Just for the heck of it, I did a little part matching and put in another
    HOT, fired it up. I got the normal relay clicking sounds, heard the HV and
    then it went to hissing, corona hiss? Almost like it's arcing inside the
    flyback. Few seconds later, the HOT goes again as the power supply went back
    to cycling.

    Unplug the monitor, wait a few minutes. Check the filter caps, make sure
    they're discharged -- all good. I look over the board for cold solder joints
    or burn spots and I come across a relay with 6 of the 8 pins where the
    solder looks like it vanished. I resolder it, put another HOT in and fire it
    up. I get the normal sounds and it returns to hissing. I power it off and
    there was a "poof" kind of sound and dust shot out from between the flyback
    and the top of the PCB. It didn't smell so well either.

    I'm certainly not trained to work on monitors/TVs, but I keep my hands away
    from what I know is dangerous =) At this point, given the sound of the
    flyback, I would almost say it's shorted inside. Below is a link of me
    powering it up with the mic about 5" away. I then move the mic towards the
    solder side of the flyback. The first "click" you hear is the power switch,
    the rest are relays.

    http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

    http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

    Thanks,

    Tim
     
  2. James Sweet

    James Sweet Guest


    I would suspect the flyback, you might be able to tell if you power it up in
    a dark room and look, try putting a lightbulb in series with the B+ line.
     
  3. Mike

    Mike Guest

    same problem with a duel HOT viewsonic.

    If your familiar with a P775

    Its probably a combination of both the flyback and driver transformer.
     
  4. Jerry G.

    Jerry G. Guest

    If you can find the parts, replace the flyback, driver transformer, change
    the HOT again (re-damaged), verify the power supply specs, and do an ESR
    test on all the capacitors in the power supply, and scan circuits. Replace
    any caps that are high in ESR.

    I think you will find it a more feasible project to replace the monitor.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    Hello,

    My dad's monitor decided to call it quits on him w/out any warning. It's a
    no-name monitor with a Samsung tube and a ProView microcontroller. He did
    say he heard a paper-rustling type sound before it went. I can only imagine
    it was the flyback doing that. I go to turn it on and I just hear the power
    supply cycling and the green LED on the front is flickering. I do a little
    digging, check for obvious shorts (HOT, caps, etc) and discover that the HOT
    is shorted. I yank out of the circuit and test it off-board -- she's dead.
    Just for kicks, I measure Vec of the HOT while it was out of circuit and I
    measured 62V.

    Just for the heck of it, I did a little part matching and put in another
    HOT, fired it up. I got the normal relay clicking sounds, heard the HV and
    then it went to hissing, corona hiss? Almost like it's arcing inside the
    flyback. Few seconds later, the HOT goes again as the power supply went back
    to cycling.

    Unplug the monitor, wait a few minutes. Check the filter caps, make sure
    they're discharged -- all good. I look over the board for cold solder joints
    or burn spots and I come across a relay with 6 of the 8 pins where the
    solder looks like it vanished. I resolder it, put another HOT in and fire it
    up. I get the normal sounds and it returns to hissing. I power it off and
    there was a "poof" kind of sound and dust shot out from between the flyback
    and the top of the PCB. It didn't smell so well either.

    I'm certainly not trained to work on monitors/TVs, but I keep my hands away
    from what I know is dangerous =) At this point, given the sound of the
    flyback, I would almost say it's shorted inside. Below is a link of me
    powering it up with the mic about 5" away. I then move the mic towards the
    solder side of the flyback. The first "click" you hear is the power switch,
    the rest are relays.

    http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

    http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

    Thanks,

    Tim
     
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

-