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CRT monitor problem: Picture magnifies by itself and loses brightness

Discussion in 'Electronic Repair' started by Andreas Apel, Jun 10, 2007.

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  1. Andreas Apel

    Andreas Apel Guest

    Hi!

    I have a weird problem with my 20" CRT monitor. Every now and then
    (there are always some hours between the incidents), the picture gets
    bigger (kinda like zooming in) and at the same time loses brightness.
    This 'zooming process' lasts for about one second.

    After that, the picture is automatically reset and totally normal again.

    The monitor does not make any unusual sounds during the occurences. It
    is a "Gateway 2000", model "VX 1100". I have never had any problems with
    it before.

    I have never heard of anything like that, but I suppose that some
    electronics part is broken and cant manage to direct the electron beam
    correctly anymore.

    Now, I am not really adept at this subject. Is this dangerous (e.g.
    implosion)? And also, what could be the reason for that problem?

    Thanks in advance!
    Andreas
     
  2. mc

    mc Guest

    I believe this symptom indicates reduction of high voltage. The electron
    beam becomes fainter but also easier to deflect, so the picture becomes
    bigger. I'll let others comment on how to fix it.
     
  3. Meat Plow

    Meat Plow Guest

    Sounds like it's Blooming. Problem in the HV regulation, deflection B+ or
    a few other things. Probably should start looking for a new monitor.
     
  4. Guest

    Classic symptoms of nosediving EHT voltage. And thats usually due to
    insulation breakdown. Once that begins, each successive arc worsens
    things, so your monitor's not got long left in this world.

    A good vac/brush of the EHT bits might clear it if youre lucky, but
    probably not.


    NT
     
  5. Jerry G.

    Jerry G. Guest

    The EHT (Extra High Tension or High Voltage) is decreasing. The beam
    current goes down, and thus it is easier to have beam deflection, and
    that is why the picture gets larger.

    The common causes can be the HV multiplier assembly, or a voltage
    regulation problem.

    I would be considering a new monitor. The cost of servicing your monitor
    would not be worth it. The new monitors are far improved.

    --

    Jerry G.


    Hi!

    I have a weird problem with my 20" CRT monitor. Every now and then
    (there are always some hours between the incidents), the picture gets
    bigger (kinda like zooming in) and at the same time loses brightness.
    This 'zooming process' lasts for about one second.

    After that, the picture is automatically reset and totally normal again.

    The monitor does not make any unusual sounds during the occurences. It
    is a "Gateway 2000", model "VX 1100". I have never had any problems with
    it before.

    I have never heard of anything like that, but I suppose that some
    electronics part is broken and cant manage to direct the electron beam
    correctly anymore.

    Now, I am not really adept at this subject. Is this dangerous (e.g.
    implosion)? And also, what could be the reason for that problem?

    Thanks in advance!
    Andreas
     
  6. Jeff, WB8NHV

    Jeff, WB8NHV Guest


    I agree with the others. Your monitor will probably go completely
    dead eventually; I'd get a new one as well if it were me. I've gone
    through two monitors on my 7-year-old IBM Aptiva 595 and am on my
    third (Hewlett-Packard Pavilion MX70), but when this one eventually
    dies I'll just pitch it and get a new FP (flat panel) monitor. The new
    FPs are better than CRT monitors and take up less room on a desktop.
    That's all we see anyway in businesses, etc.--FP monitors; no one
    (that I know of, except myself) uses CRTs anymore. Everywhere you look
    noiwadays--well, almost--flat-panels are the rule rather than the
    exception.
     
  7. Andreas Apel

    Andreas Apel Guest

    I am really impressed with how fast all of you answered. Hadnt expected
    that. It is nice to know what is happening inside my CRT now. Thank you!

    I will definitively replace it with a flat panel, but I'd like to know
    if I can use the CRT safely until I can get a replacement.

    Put in other words: Will my CRT die quietly or will it go with a big 'bang'?
     
  8. Guest

    theres not enough energy in the EHT to do anything nasty. It just wont
    fire up one time, and that'll be it.


    NT
     
  9. b

    b Guest

    just because 'everybody has them' , of course, does not mean we all
    have to ditch our CRTs.
    I won't be - the flat panel (LCD I presume you mean by flat panel)
    ones I saw when out shopping late last year were largely awful -
    poor black level and colour bleed. Howver they do take up less room
    which is a plus.

    I say to the OP : If you're not depsperate to save 10" of desk space
    check your local frecycle, you will find people giving away good
    monitors and it would be nice to 'save' one from the landfill instead
    of just going out and buying some new thing that will probably last 18
    months before dying!

    -B.
     
  10. b

    b Guest

    Before condeming it, you might want to leave it unplugged overnight
    (to allow the main capacitor to discharge) then open it up and check
    for cracked solder joints around the power supply and line stages.
    many faults are caused by stuff this simple. see www.repairfaq.org for
    tips on how to go about it. All you need are screwdrivers and a
    soldering iron.

    If you can't find the problem, it's not worth taking in for repair. It
    should be Ok to use but i wouldn't leave it unattended just to be
    sure.

    Se my other post for suggestions on where to find a new one for free!
    good luck.
    -B
     
  11. Jeroni Paul

    Jeroni Paul Guest

    Jeff, WB8NHV ha escrit:
    We use flat panels at work and I am not too impressed. Unless used at
    their native resolution, they look less sharp than a good monitor, and
    problem is for a 15 or 17" monitor the native resolutions are too big
    so everything looks too small. Monitors are better at handling all
    sorts of resolutions.
     
  12. YD

    YD Guest

    Once you have it open brush off all the dust that's probably
    accumulated over time. Use a round soft brush and if possible, follow
    it with a whiff of compressed air. One possibility is that the dust is
    shunting off the EHT or other HV.

    - YD.
     
  13. Peabody

    Peabody Guest

    Jeroni Paul says...
    I have to agree. Seeing is not one of the things I do
    particularly well, so I run my 19" CRT at 800x600. You
    can't really do that on a flat panel, and changing the DPI
    setting in XP gives you some strange artifacts. I'm told
    that's much improved in Vista though, so maybe there's hope
    for me yet.
     
  14. mc

    mc Guest

    Or in Windows XP if you turn on ClearType.
     
  15. James Sweet

    James Sweet Guest


    I've found the opposite to be true for me, it's been hard to find a flat
    panel with sufficiently high resolution. I'd love to have a 20" with a
    1920x1440 resolution, I tend to keep a lot of things open at once and like
    to have lots of space on my desktop.
     
  16. mike

    mike Guest

    This ain't what you asked, but I'd be concerned...
    The death of the monitor is NOT your primary concern.
    CRT monitors are run at about the maximum voltage you can get away with
    without generating excessive X-rays.
    If your voltage is normal but dropping as you increase brightness, no
    problem. But what if it's unregulated and going HIGHER when you turn
    down the brightness??? That's what happens when the bleeder resistor
    goes open.
    Can't tell from your description. But how much risk do you want to
    take with your eyesight?

    Where'd I put my flameproof suit??? OK, let me have it...

    mike
     
  17. Andreas Apel

    Andreas Apel Guest

    Before condeming it, you might want to leave it unplugged overnight

    Thanks to all of you! I really appreciate your help.

    I might open it up just because I want to know what it looks like on the
    inside, but a flat panel will give me so much more space on my desk, so
    I am actually looking forward to the day the CRT doesnt work anymore!

    Andreas
     
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