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CRT Monitor loses Green

Discussion in 'Electronic Repair' started by [email protected], May 14, 2010.

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  1. Guest

    My CRT monitor loses the green from time to time. Then the screen is
    all pink in the background and I can only see red and blue. Just
    about the time I'm going to toss it, the green comes back and it has
    the excellent color it's had for years. I really hate to toss it out.
    I know a fair amount about electronics and have done some tv repair.
    This is a 15" computer monitor so it's basically a tv without a tuner.
    Besides that, it seems that the only way to get a CRT monitor these
    days is a used one on ebay or a garage sale. I really do not want a
    LCD monitor, they're too hard to see if they are at a slight angle,
    and because I edit graphics, the low priced LCD screens are just too
    low in resolution and I can not afford a high end one.

    Any idea what might be causing this? The green may be gone for a few
    hours or as much as 2 days. Then suddenly it pops right back. The
    screen is not only ugly right now (no green at the moment), but hard
    to see because it's brightness is reduced without the green. I'll
    probably his some garage sales this weekend, but I'd still like to see
    if i can fix this one. Appreciate any help.

    Thanks

    James
     
  2. Start by checking the cable for an intermittent contact or wire. It could be
    something as simple as that.

    If you have access to another monitor+cable, use them to confirm that the
    problem really is with the monitor, and not somewhere else.
     
  3. PeterD

    PeterD Guest

    Bad cable or connector likely.
     
  4. Grant

    Grant Guest

    Start tapping (bashing) the thing with a hammer (well, I used the plastic
    handle of a large screwdriver :) See if you can locate where the
    intermittent connection is.

    A while back I had a monitor that dropped a colour like yours and even
    after opening the thing up and remounting every connector I could see,
    right through to the CRT socket, I never found the fault.

    By the time I retired the monitor the case plastic was quite marked in
    places from the fairly hard bashing I gave it to get the colours back.

    Grant.
     
  5. Winston

    Winston Guest

    On 5/14/2010 9:48 AM, Grant wrote:

    (...)
    Suggest gently wiggle the video connector on the back.

    --Winston
     
  6. Is it on a KVM? I had one go bad that-a-way.

    Jonesy
     
  7. Assuming that the problem is within the monitor, and not
    I didn't suggest that the cable was the problem, but rather that that was
    where the OP should begin troubleshooting. Has he?
     
  8. mike

    mike Guest

    You should, as others have suggested, look for bad connections in the
    signal path. Put a scope on the CRT so you can look for signal when it
    goes out.

    If it turns out to be the CRT, and you've exhausted all other options,
    you might try hitting it with a stun gun.
    I've fixed shorted CRT elements that way.
    Be careful to get all the electronic stuff VERY FAR AWAY so you don't blow
    up good semiconductors in the process.
     
  9. jerryg50

    jerryg50

    57
    0
    Apr 18, 2010
    Start by checking the cable between the monitor and the computer.


    For this procedure, you should be an experienced TV / monitor service tech:
    On the inside of the monitor, check for cold solder connections starting from the input circuits along the path of the green channel. First check for cold solder connections.

    If a cold solder cannot be visually found, jig the monitor circuit assemblies so you can run the monitor with the boards exposed. Instigate or wait for the fault. Use an oscilloscope and follow the video path for the green to see where the loss is occurring. Once you find the signal loss stage, start troubleshooting from there.

    --

    As for myself, I would toss any CRT monitor. If you go more on the costly side, there are some excellent LCD monitors that no affordable CRT monitor can beat. The higher end LCD monitors don't have a bad viewing angle problem. I found only in the low cost LCD monitors the viewing angle was critical.

    As for health issues, the LCD are much better. There are no ELF emissions, and no UV and X-Ray radiation. LCD monitors are more environmentally friendly. They use much less electric power, and are much less polluting when they have to be disposed of. I would never want to have a CRT monitor again since I've been using LCD.


    Jerry G. :D





     
  10. Guest

    Yes, I tried. The cable is part of the monitor so I cant just change
    it. But I did wiggle it around on the back of the computer plug and
    the rest of the cable. I tried a different monitor on the puter and
    tht worked fine. I plugged the bad monitor into another puter and it
    was still lacking green. So, it's the monitor. I just replaced it
    with another CRT monitor I found at a garage sale for a buck. The new
    one is a 15" and the bad one is a 17", so I am going to open it and
    look for bad connectors and the CRT plug, loose solder joints, etc.
    It's not worth spending a lot of money or time on it, but I'll see if
    I can bring it back to full color. The last time the green went out,
    it stayed out for 11 days straight. That was getting real annoying to
    use. Luckily over the weekend I found this one at the garage sale.

    Thanks
     
  11. Winston

    Winston Guest

    On 6/9/2010 5:41 AM, wrote:

    (...)
    Have you spritz'ed the video connector with contact cleaner?

    If you can locate a loose connector to mate with the monitor
    cable, you can run a continuity test. Merely 'buzzing' the
    'green' pin to the inside of the monitor won't necessarily
    tell you the complete story.

    --Winston
     
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