1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Dead Pixels?

Discussion in 'Projectors, Screens & Video Processors' started by Canary_Jules, Jan 25, 2003.

  1. Canary_Jules

    Canary_Jules
    Well-known Member

    Joined:
    Jan 25, 2003
    Messages:
    3,234
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Leicester, UK
    Ratings:
    +739
    Hi, I just bought a Sony VPL SC50 on e-bay for £600. I hope this works out to be a decent buy since I haven't got the £1500 plus for a new machine. On using the projector I notice there is a load of background 'gunk' plus about 8 areas where I either get red or green spots. The spots aren't visible when the default blue screen is used but are definitely visible when the screen goes black. I read on the forum that dead pixels are quite sharp and focused but these ones are pretty fuzzy. So what are they? Can anyone help? I think I probably need to get the machine serviced!

    Thanks for any help!
     
  2. theritz

    theritz
    Active Member

    Joined:
    Aug 17, 2002
    Messages:
    2,451
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Ireland
    Ratings:
    +27
    Hi Canary_Jules, welcome to the Forum.

    I don't know what "gunk" means, but if you're seeing green or red "blotches" on a grey screen, then it is most likely to be dust on the LCD panels. If this doesn't affect the appearance of the image from the projector, then I'd leave it alone. I have two dust spots on mine and they don't bother me at all.

    WARNING: The Following is to be attempted at your own risk !!!!

    Assuming you're reasonably competent, you can sort this out by removing the cover of the projector and blowing around the area of the LCD panels with a can of compressed air, which is sold in photography shops. WARNING: You should ensure that the can is only blowing out air, and not any of the propellant, which comes out as a liquid - this would not be good for the insides of your Projector !!!


    Have fun with your new toy !


    Sean G.
     
  3. Canary_Jules

    Canary_Jules
    Well-known Member

    Joined:
    Jan 25, 2003
    Messages:
    3,234
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Leicester, UK
    Ratings:
    +739
    The 'gunk' and the coloured spots are two different issues. I think the gunk looks like dust on the prism, but what I really want to know is whether I have dead pixels or not. They are green and red and as you say are more like fuzzy blotches than squares. Iis that what a dead pixel looks like? I am hoping it is just muck that can be cleaned off by a good service! Thanks again.
     
  4. theritz

    theritz
    Active Member

    Joined:
    Aug 17, 2002
    Messages:
    2,451
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Ireland
    Ratings:
    +27
    Hi again Canary_Jules,

    If they look like blotches than its definitely dust - dead or stuck pixels appear as permanently lit Green, Red or Blue - depending which panel they're on.

    A service centre should be able to give it a clean out and "tune up" using the Service Menu.

    Good luck,


    Sean G.
     
  5. Canary_Jules

    Canary_Jules
    Well-known Member

    Joined:
    Jan 25, 2003
    Messages:
    3,234
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Leicester, UK
    Ratings:
    +739
    I am now convinced that I have only one dead pixel and all the rest of my image problems relate to dust! It needs a damn good clean. I have checked out a few places for quotations for a clean but they are all in the region of £200-£250 which seems excessive to me. So, unless someone knows of a reasonable place that I can get the machine serviced at I am left with doing it myself with an air can. Sounds a bit scary though. Any tips? Anyone done this themselves before?
     
  6. LV426

    LV426
    Administrator Staff Member

    Joined:
    Jul 14, 2000
    Messages:
    12,752
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Somewhere in South Yorkshire
    Ratings:
    +4,906
    First of all - to work out what is (or isn't) a dead pixel:

    If you have your picture properly focussed, and then get close to the screen, you will see that the picture is made up of coloured squares - with a black 'grid' defining the edges of these squares. These are your pixels. If you have one or more permanently bright or dark spots that exactly coincides with one or more of these squares (ie is clearly focussed and bounded by the black grid) then you have a bad pixel.

    Anything that is more diffuse, or less clearly defined is probably dirt. Often, if you defocus the projector in one direction or the other, dirt particles will come into clearer focus - you will be able to see the shape of a fine thread or fibre.

    Can't speak for the PJ you have, but I can say that I've blown the optics in my VW10 clean twice, now. It was a ten minute (max) job to demount the thing from the ceiling, dismantle it, clean it, and reassemble it, and was totally effective at removing dust.

    Use an aerosol airblower - you can buy this from Maplins - and make damned sure that you don't allow any of the liquid in the can to reach your optics before it evaporates. Try the blower on a window or mirror first to practice.
     
  7. Canary_Jules

    Canary_Jules
    Well-known Member

    Joined:
    Jan 25, 2003
    Messages:
    3,234
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Leicester, UK
    Ratings:
    +739
    Thanks!

    Advice gratefully received.
     
  8. chic

    chic
    Well-known Member

    Joined:
    Jul 1, 2001
    Messages:
    5,975
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    glasgow
    Ratings:
    +871
    i have cleaned dust from inside my ptae twice and its very easy to do, bit nerve racking at first but the easy way to do is open up the pj and sit it on its side and blow the air over the panels keeping the can of air upright so no liquid comes out give the can a couple of squirts away from the pj to remove any liquid from the nozzle the swirt the air in short bursts into each of the 3 panels .
     
  9. Colonial Marine

    Colonial Marine
    Standard Member

    Joined:
    Dec 8, 2000
    Messages:
    37
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    6
    Location:
    London, Uk
    Ratings:
    +0
    Just a thought, perhaps get your can of air from a photographic supplier like Jessops. They will most likely be able to supply air which has no contaminants in it.
     
  10. Canary_Jules

    Canary_Jules
    Well-known Member

    Joined:
    Jan 25, 2003
    Messages:
    3,234
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Leicester, UK
    Ratings:
    +739
    Just thought I'd let you know what happened. I summoned the courage to take the machine apart and found a system of mirrors and lenses that were really dirty. So I pulled each one out and cleaned. Now there is only one bright coloured patch proving that they weren't dead pixels. Picture is much better. But, it appears that there is dust stuck on the lcd panels that won't shift with compressed air. It is this dust that shows up as background 'gunk' on white or bright images. Would I be risking damage to gently wipe the panels with a lens cloth? Has anyone done this?
     
  11. SGDVD

    SGDVD
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    .....
     
  12. LV426

    LV426
    Administrator Staff Member

    Joined:
    Jul 14, 2000
    Messages:
    12,752
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Somewhere in South Yorkshire
    Ratings:
    +4,906
    Yes, in my experience. Just make sure you practice (say, on a window or mirror) first to ensure you have a technique that involves the can blowing gas only - no liquid. And ensure that your mirror or window has no residue on it, afterwards.
     
  13. Daftboy

    Daftboy
    Active Member

    Joined:
    Jan 8, 2004
    Messages:
    505
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Ratings:
    +12
    How about using a decent cotton bud to wipe and the gas can to blow it off?
     
  14. LV426

    LV426
    Administrator Staff Member

    Joined:
    Jul 14, 2000
    Messages:
    12,752
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Somewhere in South Yorkshire
    Ratings:
    +4,906
    I doubt you'd get a cotton bud into the LCD array. You certainly couldn't without some serious additional dismantling on my VW10. And, I suspect that physical contact with such a thing may do more harm than good anyhow.

    I have heard of people who, faced with a stubborn bit of stuff, have taken the corner of a piece of paper to try and dislodge the particle, before blowing. I have never had anything that was stuck to that extent, though so I can't comment on the validity of this technique.
     
  15. SGDVD

    SGDVD
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    ......
     

Share This Page

Loading...