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Dismantling Thomson TV 22FB1133

Rocout -  
baladur13 Posted messages 47339 Registration date   Status Moderator Last intervention   -
Hello,

My Thomson 22FB1133 television loses sound after 20 minutes, it is probably a thermal issue with a component.
I can't open the television to access the electronics; how should I proceed after removing the 8 visible screws to separate the plastic back from the chassis?
Thank you for your help.
Rocout

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3 answers

  1.
    Andy31200 Posted messages 26918 Registration date   Status Moderator Last intervention   12 203
     
    Hello,
    Have you dusted the air vents properly?
    Does the fan turn on?

    --
    I call a spade a spade *
    *in French in the text
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    1. Rocout
       
      Hello,
      Thank you for your response:
      The vents have been dusted off, I don't think there is a fan in this TV.
      I want to open it to access the electronics, but I can't do it: after removing the 8 visible screws from the plastic cover, I can't seem to take off this cover which must be clipped somewhere? There are indeed two slots at the bottom side, but inserting a flat screwdriver doesn't yield any results and I don't want to force it; there must be a trick?
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  2. baladur13 Posted messages 47339 Registration date   Status Moderator Last intervention   14 395
     
    Hello,
    Personally, looking at the image of the back of the television shown in the manual on page 4, I can see at least 17 screws (possibly more if any are located under the part covered by the stand).

    The manual: http://www.mediacenter.tcl.eu/uploads/common/THOMSON_MT31_FR.pdf
    Taken here; https://www.mythomson.com/uk_en/manuals-and-downloads-326-uk-en?query-download=22FB1133&id_univers=

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    1. Rocout Posted messages 1 Status Member
       
      Hello,
      Thank you for your response; I'm sorry, I mixed up some numbers in the reference for my TV, it's 22FB3113 and not 1133.
      I finally managed to open it, you need to unclip the plastic frame surrounding the screen from the back of the television (or casing) with a spatula, starting at the slots located at the bottom of the TV.
      I am facing a very dense multilayer board of about 300 cm², which includes all the functions.
      Visually, it seems perfect; the TV was purchased in March 2016, the sound becomes choppy after about twenty minutes and then disappears completely.
      Before buying another one of the same size for €150 (what a waste!), I want to try to fix it with the help of the forum.
      Best regards
      Rocout
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  3. Andy31200 Posted messages 26918 Registration date   Status Moderator Last intervention   12 203
     
    Have you thoroughly examined all the capacitors on the sound card to spot any bulges or leaks? (the wires to the speakers come from this card)

    --
    I call a spade a spade *
    *in French in the text
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    1. Rocout
       
      Good evening,
      Thank you for your response.
      Everything is on the same board, I checked the amplifier area and saw nothing unusual, the board is recent, like new, manufactured on March 13, 2016. The sound fails after about twenty minutes of the television being turned on.
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      1. baladur13 Posted messages 47339 Registration date   Status Moderator Last intervention   14 395 > Rocout
         
        This could indicate a cold solder joint...
        after a certain time, the heating components cause the circuit to deform. This minimal deformation at first leads to a decrease in sound (the solder behaves like a resistor) followed by a total cut-off.

        Modern devices operating at low voltage (outside the 220v power supply area) should be checked to see if applying pressure on the components in the sound area can help identify the issue.
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