Will a magnetically unshielded subwoofer cause permanent damage to a CRT?

Discussion in 'Archived Threads 2001-2004' started by Mike Lenthol, Mar 9, 2003.

  1. Mike Lenthol

    Mike Lenthol Second Unit

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    I can see slight discolorations when moving the subwoofer around and the picture is still, but the effect is virtually invisible without knowing what to look for. Doesn't bother me in the least, but will prolonged exposure to the magnetic field from the sub do any irreversible damage to the TV? (Just in case I want to sell it later or something)
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Yes, if left long enough, which may not be that long.
     
  3. Mike Lenthol

    Mike Lenthol Second Unit

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    Neil, can you please indulge me in the technical side? Not that I'm questioning it, just interested how it would work.
     
  4. Kevin P

    Kevin P Screenwriter

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    To make a long story short, the magnetic field in the speaker can magnetize the shadow or aperture mask in the CRT, causing a discoloration that requires degaussing to get rid of it. Also, an electron beam deflected by a magnetic field can cause the mask to heat up and warp, causing permanent damage.

    It's best to keep those magnetic fields away from your TV.

    RPTVs don't use shadow masks, so these issues don't apply to them. But a magnetic field can throw off convergence in a RPTV.

    KJP
     
  5. Jack Briggs

    Jack Briggs Executive Producer

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    As I just finished telling someone else on this Forum, I ruined two perfectly good Sony TVs by exposing them to unshielded speakers (in the last case, it was a Polk LF-14 woofer system situated within a foot and a half of the Sony). In both cases the damage was permanent.
     
  6. james e m

    james e m Second Unit

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    How can you tell your tv has been damaged?

    James
     
  7. Neil Joseph

    Neil Joseph Lead Actor

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    Usually, there are discolourations to the side of the display nearest to where the magnetic field (speaker) was placed. It is fairly obvious. If you are starting to notice this, remove the speaker immediately then turn the TV off and unplug it for a couple of hours. When you plug in and turn back on, the TV will have degaussed itself and hopefully fixed itself, assuming it can.
     

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