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TV went Fffttt and now covered in coloured rings

Discussion in 'General TV Discussions Forum' started by tdodd, Jun 18, 2005.

  1. tdodd

    tdodd
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    FWIW here is a picture of the problem (see link below). Geometry also went a bit squiffy when the colours arrived and I cannot correct it from the engineering menus for the TV. Maybe there are controls there that I do not understand but I am unable to properly size and position the display (for zero overscan) as the visible picture is offset to the right and shifting the image to the left just makes the picture disappear under a false edge about a centimetre in from the proper edge of the visible (unmasked) display area.

    Whats even more strange is that the screen should be blue all over - pretty much the blue that you see around the central green "bullseye" - and the text should all be white. The text has remained white all over the screen and yet the coloured areas are messed up. I'm hoping that's a big clue to the problem and hopefully the solution. Any ideas whether this can be fixed and at what sort of cost? Thanks :)

    http://www.easytiger.plus.com/TV/TV.jpg
     
  2. DRGL

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    Looks like the degaussing coil has gone pear shaped,possible thermistor failure?
     
  3. tdodd

    tdodd
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    Elsewhere someone mentioned that it might be the shadow mask having moved. I gave the TV a tap and the coloured rings wobbled while the actual picture remained stationary. I don't know whether that experiment bears out the shadow mask theory or degaussing etc. but I'm not hopeful :-(
     
  4. DRGL

    DRGL
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    very much doubt that TBH...........
     
  5. LV426

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    Looks too even and regular to be a degaussing failure. The wobble does tend towards a loose shadow mask. New tube. I hope it's under warranty.
     
  6. GaryB

    GaryB
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    It does look like a detached shadowmask. Stick an ear near the face of the CRT (mind the static). You can sometimes hear a pinging noise as the shadowmask moves around slightly.
     
  7. red16v

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    Hi, I'm curious, why would the shadowmask have moved ? I'm presuming the telly was 'just sitting there' when the fault developed ? regards, yt.
     
  8. tdodd

    tdodd
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    I have had to give the TV a bit of a knock on several occasions as there is a dry joint somewhere in the audio circuitry. Normally this is not an issue because my audio mostly goes through digital or analogue links to my AV amp and bypasses the TV altogether. But sometimes when I'm recording something on Sky I may need to suffer some terrrestrial TV and then I my need to give the TV a little encouragement to output sound to both channels. I guess maybe this physical approach to problem solving may have taken its toll on the shadow mask.

    But at the time of the fault the TV was just sitting there doing nothing. I turned it on from standby with the remote and there was a small unusual "Fffftttt" noise and when the picture appeared there were the coloured rings as well.
     
  9. red16v

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    Hi, well you'd normally have to give the crt a terrific whack to dislodge the shadow mask. Nonetheless it does look like something 'terminal' with the crt. Your first note is the most informative, obviously there is a large beam landing error being caused by something - hence the large 'purity' errors yet curiously the white text is still correct at the extreme areas of the raster and it seems to be focussed. Does imply that the convergence is still correct (ish) but that the beams are not landing correctly. Without seeing it in the flesh it does seems to be an internal crt fault. Unless I've missed soemthing I don't think you've told us the model/age - it may not be worth spending money on, especially if it has an audio fault (although a true dry joint would be easy for a service engineer to track down). Regards, yt.
     
  10. tdodd

    tdodd
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    The TV is a JVC 32" 100Hz jobby bought, I think, between six and seven years ago. Model number is AV-32WFP1EK
     
  11. LV426

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    In that case, my guess is that the cost of any repair (or diagnosis, even) is probably more than it's worth. New TV time........
     

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