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Help! is my Mits 40" Tube dead??

Discussion in 'Televisions' started by RGMetro, Dec 23, 2004.

  1. RGMetro

    RGMetro
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    there's a black box in the center of the tv that occupies about 80 percent of the tv. the image from the tv is present on the outside of the box.

    if you adjust anything on the tv which cause the tv generated text/graphics, the box goes away. as soon as the tv text disappears, the box comes back

    you can enter the normal tv menu and that occupies the entire screen...no black box until you exit to the picture...

    i went into the service menu...it keeps text on the screen until you exit....so for now we watch with VHDRV 0 1 0 in green text in the middle of the screen.

    any ideas of what's causing this?

    thanks,

    RG
     
  2. ScootermanRoger

    ScootermanRoger
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    If the "black box" is sharply defined, it could be a picture processing fault, but more likely, if the box blends in to the picture, and tends to come and go according to the overall brightness of the picture the TV is trying to display, causing "breathing" of the box/picture, then a possible cause could be a failing "tripler" - that's the five stick stacked diode device that sits on the line output transformer that triples the voltage from the transformer (which assumes the transformer itself is not faulty) and applies it to the CRT (tube) under that big circular plastic "sucker" that sits on the tube halfway between the tube neck and the outer edge.
    WARNING! Do not lift this "sucker" even with the set turned off, as the tube acts like a giant storage capacitor, storing up to 25,000 volts ready to catch the unwary! It's not pleasant! Believe me, I know! :(
     
  3. RGMetro

    RGMetro
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    thanks for responding!

    its actually sharply defined. almost like its being superimposed over what ever image is on the tv.

    someone suggested i "cold reset" the tv. but i have no idea what that means. is that simply unplugging it?
     
  4. ScootermanRoger

    ScootermanRoger
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    A sharply defined box suggests a picture (video) processing fault, so the chances are that your tube is ok. Re: cold reset, yes try unplugging it and reconnect after an hour or so, but I don't think this will work. It's more a trick for digiboxes. But give it a go. Also disconnect all accessories from scart sockets, just in case an external reason is dragging the TV down. Good luck!
    Also, if the set has a "normalise" button to return to initial brightness/contrast settings, try that as well.
     

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