Testing the Tube (repair)

Discussion in 'Displays' started by Aaron Silverman, Jan 26, 2005.

  1. Aaron Silverman

    Aaron Silverman Executive Producer

    Jan 22, 1999
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    Aaron Silverman
    Hi gang,

    My bedroom TV (10-year-old 31" Panny) has suddenly developed a video problem -- the picture is green, as though the tint control is turned all the way to the green side. The tint control has no effect. Everything else seems fine.

    I described this to a TV repair guy (who was recommended to me), and he said that it's likely one of two things:
    • The picture tube is hosed, and it's time for a new TV.
    • The video board is hosed, and it'll cost about $40 to replace it.
    Since the TV is pretty heavy, and I want to avoid carrying it to the repair shop if possible, I'd like to open it up and try to determine whether the picture tube is in fact dead. Is there an easy way to check it? (My degree is in electrical engineering, and although it's been years since I've opened up any electronics, I can probably be pretty safe about it and know my way around a voltmeter.)

    I'm hoping that I might be able to eyeball it or test something simple with a meter. Any advice is appreciated!

    (Note that I definitely want to avoid replacing the TV if possible -- I know it's old, but anything I buy now would probably just be a cheap interim solution.)
  2. Allan Jayne

    Allan Jayne Cinematographer

    Nov 1, 1998
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    Since you have some electrical engineering experience, here are some ideas for starters.

    1. Gently tap the neck of the picture tube with a non-metallic non-carbon (like a pencil) stick, in case some parts inside got warped.

    2. Remove the socket from the back of the picture tube and press it back on, that will clean the contacts. Also undo and redo any other snap on or press on connection you see.

    3. Inspect the filaments in the picture tube neck. Three lit means at least that part of the tube is working, but two lit means the tube is shot. One lit sometimes doesn't mean anything because some tubes only have one filament. If you see one lit and also two more dead, knowing what to look for, the tube is shot, although two dead is not too common.

    (Don't get electrocuted by high voltage, or spattered by flying glass from a broken tube. If you don't know about the proper precautions, you should not be poking around inside at all.)

    Video hints:

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