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CRT Monitor Problem

Discussion in 'Electronic Repair' started by [email protected], Nov 18, 2007.

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  1. Guest

    Hi,

    About a week ago my 19" CRT started displaying an extremely distorted
    picture. It intermittently goes into a state where the picture is
    broken up into fuzzy lines (I can't describe it well) and the
    slightest tap on the case could cause it to return to normal
    (temporarily) or get worse.

    I've checked for any broken video connections inside or outside, but
    there are none. What's weird is that I ran the monitor with the
    plastic case off and the problem disappears. But as soon as I put the
    case back on the slightest movement or tap near it makes the picture
    go crazy again.

    Does anyone have any ideas as to what the problem could be? Could the
    case be causing some sort of interference?

    Thanks in advance for any comments.
     
  2. Arno Wagner

    Arno Wagner Guest

    Contact problem affecting the sync-signals. May be in the external
    connector or in some internal ones.
    Probably removing the case puts the problematic connection
    under different mechanical stress than when it is on. This
    often improves contact conditions.
    No. This is very typical for a broken solder point or a marginal
    connector. This is also very hard to find. Fix is easy once
    you know here the problem is. If is a connector, you may
    want to remove and reseat every connector you can get at. Be
    careful that the CRT may remain charged up to some hours
    after it has been disconnected from power.

    Arno
     
  3. Guest

    Thanks for the quick reply. I did look to see if there would be any
    obvious stress from the case being on, but you're right it is probably
    going to be hard to find and somewhere *not* obvious.
     
  4. No. This is very typical for a broken solder point or a marginal
    You now have to decide whether you want to systematically resolder "all" the
    joints, rather than trying to find the specific bad connection.
     
  5. hr(bob)

    hr(bob) Guest

    An other alternative is to put the case back on, but with something
    inside the case that "bends" the guts slightly and see how long that
    "fix" works - maybe.
     
  6. James Sweet

    James Sweet Guest


    These sorts of problems are actually pretty easy to track down most of the
    time. Find yourself an insulated stick of some sort, my favorite is the
    plastic rod from a set of window blinds but I've used wooden dowels, plastic
    pen bodies, etc. Remove the cover from the monitor, power it up, and start
    gently poking and tapping areas of the board until you find the ticklish
    spot, and then flip the board over and inspect carefully for cracked solder
    joints.
     
  7. Franc Zabkar

    Franc Zabkar Guest

    Tap test the open monitor with an insulated rod. That may narrow down
    the location of a dry soldered joint.

    - Franc Zabkar
     
  8. JANA

    JANA Guest

    If you are tapping on the monitor case to have a temporary repair, this
    means that there is a cold solder connection somewhere in the monitor. More
    than likely it could be on the main circuit board, one of the daughter
    boards, or a connector.

    The monitor would have to be un-assembled, and jigged up so that it can be
    worked on. The process of slightly flexing boards and connections can be
    done to try to zero in on where the fault is. Once found, then the
    connection can be re-soldered. This can be very time consuming work.

    Working on a monitor requires good electronics experience, a sound knowledge
    of monitors, and troubleshooting skills. There are many safety issues
    involved. I would suggest you take the monitor to a service centre and have
    an estimate done in order for you to make a logical decision if it is worth
    to service or not.

    --

    JANA
    _____


    Hi,

    About a week ago my 19" CRT started displaying an extremely distorted
    picture. It intermittently goes into a state where the picture is
    broken up into fuzzy lines (I can't describe it well) and the
    slightest tap on the case could cause it to return to normal
    (temporarily) or get worse.

    I've checked for any broken video connections inside or outside, but
    there are none. What's weird is that I ran the monitor with the
    plastic case off and the problem disappears. But as soon as I put the
    case back on the slightest movement or tap near it makes the picture
    go crazy again.

    Does anyone have any ideas as to what the problem could be? Could the
    case be causing some sort of interference?

    Thanks in advance for any comments.
     
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