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Image ghosting/persistence

Discussion in 'TVs' started by jtorry, Jun 17, 2002.

  1. jtorry

    jtorry
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    I have had my TV and Monitor taken away ecently to be repaired as they both had image persistence problems. The problem is that the TV and monitor I am using while my others are away have the same problem. Someone has suggested that the problem could all be down to my power supply. Can anyone offer any ideas?
     
  2. Chris Muriel

    Chris Muriel
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    You'll have to tell us more about the perceived problems.
    A ghost normally refers to multipath reception via an antenna ; if your ghost is to the right of the main image, it's because your TV is getting a 2nd signal from a slightly different path to the main one - e.g. reflected signal from a building or tower. Aerial realignment may fix this. Also certain types of aerial (especially log periodics) are more "ghost proof" than others (but have less gain per unit boom length) :(
    Do you see a "ghost". on inputs from satellite or cable TV (or even DVD) ? If you do, then your problem isn't likely to be anything to do with the above. It could be scart lead leakage/crosstalk - ensure you use fully screened (all signal leads) scarts.
    What is the TV make/model ? Likewise, what's the loan set ?
    Do the "ghosts" disappear if you remove all inputs other than the one you're watching? Try connecting 1 item at a time, then unplugging it & connecting something else (e.g. DVD, sat, cable)
    to see if you can pin down the cause by noting what seems to produce this. Again you may want to try using or varying the scart input (& lead) that you are using.
    A bit more detail , particularly after some of the above tests, should get more responses from the group.
    Chris Muriel, Manchester
     
  3. Ekko Star

    Ekko Star
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    Sounds like poorly screened cables.

    Are you using cheap Scart cables by any chance ? If you are, try snipping pin 21 and that should make the difference.
     
  4. jtorry

    jtorry
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    I think i have given a false idea of what the problem is. What happens is that the image seems to remain on the screen for too long. Eg. Bright lights leave trails behind them, and if a white or bright coloured object moves down the screen over a dark background I can still see where the image came from. This is only brief but it is more than i think should happen. I also doesn't happen on my friends tele and that is a really old one. The TV repair man said that it looked the kind of problem 100Hz sets suffer from, but my TV is not 100Hz.

    This problem occurs no matter what source the signal is from. Airal for tv, RGB scart for both DVD player and Games consoles. This seems to take away the possibility of it being due to a scart.

    The other odd thing is that i can see the same problem on my Pc monitors.

    TV: JVC AV32WFT1
    Temp TV: Old 21 inch sony

    DVD player: Pioneer 545

    Any ideas? Does anyone know if it could be due to the power supply for the house?

    Thanks
     
  5. jtorry

    jtorry
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    I have been told on another forum that the problem I am describing known as Phosphor persistence is a broblem with all CRTs. If this is the case why is it never mentioned as a problem?
     
  6. Chris Muriel

    Chris Muriel
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    I'm not sure whether modern CRTs have a longer persistance than the ones on older TVs that you found OK - does anyone know if different phospors are used in more recent tubes ?
    Also, the human eye will vary in its "memory" or persistance from 1 individual to another. I wonder whether you are more sensitive to it than most - which wouldn't be your fault of course.
    Just as some folk notice 50 Hz flicker & find it objectionable (or even in worst cases headache-producing) you may be persistance-sensitive.
    Incidentally, most Americans who see my TV at 50 Hz (plenty of them as I work for a US IC company) notice the flicker far more than I as they're used to NTSC at 60 Hz.
    You may, if my diagnosis is correct, get used to modern tube persistance (or its viewed results) over time.

    Chris Muriel, Manchester.
     

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