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Failures in antiglare coating on CRTs?

Discussion in 'Electronic Repair' started by Philip Pemberton, Jun 26, 2006.

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  1. Hi,
    I've got a Mitsubishi DiamondPlus 74SB CRT monitor here, and it looks like
    the anti-glare coating is coming away from the CRT glass. There are a number
    of "pockmarks" in the coating, and along the top and bottom edges, a 5mm area
    of the coating has disappeared, mainly around the plastic bezel. The monitor
    is three years and three months old, manufactured 44th week of 2002, on my
    desk on the 3rd of March 2003.

    The only thing the CRT has ever been cleaned with is a microfibre cloth and
    filtered water ("filtered" as in "gone through a ceramic/activated carbon
    'pure water' filter"). On one occasion shortly after I got the monitor, I used
    a CRT cleaning cloth (basically distilled water and a neutral detergent on a
    microfibre pad) but that's it.

    I had a Samsung Syncmaster 3 before the Mitsubishi, treated them the same
    way and never had any issues with the coating - the Samsung is now nearly
    eleven years old, the contrast pot is pretty much worn out, but the CRT is
    still as bright as ever...

    I'm at a loss to explain this, and the only answer I managed to get out of
    NEC-Mitsubishi (well, NEC Display Systems) was - in effect - "it's your fault,
    you can only cause that if you use chemicals to clean it."

    I've also noticed that the CRT seems to have started picking up a very
    nasty level of static charge - to the point where if my hand goes within a
    quarter inch or so of the CRT (as it does when I switch it off), I get a
    static-shock that's severe enough to cause my entire arm to spring backwards.
    Is this likely to be related to the failure of the coating?

    Can anyone shed some light on this annoying little issue?

    Thanks.
     
  2. JANA

    JANA Guest

    I have seen on some monitors where the anti glare started to degrade. The
    most common cause was during the coarse of its history, the screen has been
    cleaned with a strong glass cleaner, especially one that contains ammonia,
    or alcohol. Some types of anti glare coatings can be effected if the monitor
    was kept in a humid environment.

    As for getting shocks from the front of the CRT, check to see if the CRT
    rear wall surface is properly grounded, and that the shield around it is
    also properly grounded. Glass is normaly not conductive, therefore the
    effect you are getting is from a dielectric pickup effect.

    --

    JANA
    _____


    Hi,
    I've got a Mitsubishi DiamondPlus 74SB CRT monitor here, and it looks
    like
    the anti-glare coating is coming away from the CRT glass. There are a number
    of "pockmarks" in the coating, and along the top and bottom edges, a 5mm
    area
    of the coating has disappeared, mainly around the plastic bezel. The monitor
    is three years and three months old, manufactured 44th week of 2002, on my
    desk on the 3rd of March 2003.

    The only thing the CRT has ever been cleaned with is a microfibre cloth
    and
    filtered water ("filtered" as in "gone through a ceramic/activated carbon
    'pure water' filter"). On one occasion shortly after I got the monitor, I
    used
    a CRT cleaning cloth (basically distilled water and a neutral detergent on a
    microfibre pad) but that's it.

    I had a Samsung Syncmaster 3 before the Mitsubishi, treated them the same
    way and never had any issues with the coating - the Samsung is now nearly
    eleven years old, the contrast pot is pretty much worn out, but the CRT is
    still as bright as ever...

    I'm at a loss to explain this, and the only answer I managed to get out
    of
    NEC-Mitsubishi (well, NEC Display Systems) was - in effect - "it's your
    fault,
    you can only cause that if you use chemicals to clean it."

    I've also noticed that the CRT seems to have started picking up a very
    nasty level of static charge - to the point where if my hand goes within a
    quarter inch or so of the CRT (as it does when I switch it off), I get a
    static-shock that's severe enough to cause my entire arm to spring
    backwards.
    Is this likely to be related to the failure of the coating?

    Can anyone shed some light on this annoying little issue?

    Thanks.
    --
    Phil. | Kitsune: Acorn RiscPC SA202 64M+6G
    ViewFinder
    (valid!)| Cheetah: Athlon64 3200+ A8VDeluxeV2
    512M+100G
    http://www.philpem.me.uk/ | Tiger: Toshiba SatPro4600 Celeron700
    256M+40G
    No software patents! <http://www.eff.org/> /
    <http://www.ffii.org/>
     
  3. webpa

    webpa Guest

    Polymer anti-glare coatings degrade fairly rapidly when subjected to
    direct sunlight or any other source of UV...such as florescent lamps or
    quartz-halogen lamps. Some, but not all, anti-glare coatings are also
    sufficiently conductive as to bleed-off the perfectly normal HV
    (static) charge CRTs collect. After all, you are blasting 25-30 kV at
    a non-conductive glass fishbowl. Try wiping the CRT with a sheet of
    anti-static material intended for use in clothing dryers...wipe it on
    you chair as well. Or spray it with "Static Guard" or something
    similar. It is also possible that the glass from which your CRT is
    blown does not have its full compliment of lead. If not, it has been
    showering its front surface with X-Rays, thus degrading the anti-glare
    coating (and your chances for a long line of descendents).

    If you're worried, invest in an LCD monitor.
     
  4. Well bugger, that's probably what's done it. The monitor is at a 45-degree
    angle to a window, and the evening sun usually hits it full-on (except when I
    close the curtains, for obvious reasons).

    Interesting that the same treatment didn't kill the SyncMaster. Are LCDs
    susceptible to this problem as well?

    It does say "keep the monitor at a 90-degree angle to light sources to prevent
    reflections" in the manual, but there's nothing about the antiglare coating,
    besides the usual massive list of chemicals to avoid using on it.
    Will do - thanks for the suggestion.
    Possible, but highly unlikely.
    I might, but not until the Mitsubishi either dies or decides to go silly on
    me. Anyone know of any good brands of LCD? I was thinking along the lines of
    Samsung, or maybe Sony if someone throws a huge bag of money my way...

    Thanks.
     
  5. Guest

    Hi!
    Since they aren't coated in the same way that CRTs are, I'd tend to
    think the answer is no. However, the topmost layer of the screen is
    usually plastic and could melt if the sun got hot enough. I think it
    would take hours of very bright direct sunlight before that ever
    happened.
    I'm a big fan of the Samsung display panels. I have ones from 15 to 19
    inches in size. All of them have been great so far, with good
    brightness and sharpness. They are also reasonably priced. Despite
    somewhat heavy use, none of them have failed early on and only one was
    dead in the box. Samsung replaced it promptly.

    The one Viewsonic panel I have puts off a great display. It's not quite
    as bright as the Samsung panels, but it works. I also have an AOC
    (cheap!) display panel. It is nice looking, and the picture quality is
    certainly usable, but the backlighting is not uniform and never has
    been.

    William
     
  6. Sounds like Samsung are still making monitors then. Only problem is none of my
    regular suppliers stock them :(
    I'm not a fan of ultra-bright monitors. Heck, I run my laptop's TFT at minimum
    brightness, and the CRT at not much more than 30%.
    Like I said, I tend to shy away from the cheapies because they're usually not
    much good (and the warranties tend to be along the lines of "send it back to
    our factory in Shenzhen and wait four months for a replacement").

    Thanks.
     
  7. James Sweet

    James Sweet Guest


    I'd be more worried about the color filters in the LCD fading in the
    sun, everything else seems to.
     
  8. Ron(UK)

    Ron(UK) Guest

    That`s exactly the same as my Diamond Pro 740SB morning sun just clips
    the lower corner of the screen, and there is a patch of the coating
    missing right there. I must admit though, to one or twice cleaning the
    screen with isopropanol

    Ron(UK)
     
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