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Pincushion Problem In CRT TV

By on August 21, 2013

I have a problem with the above TV it is a Pincushion Problem Everything in the Tv works fine except that it has a pincushion problem on the two sides of the screen, I check the modulation..not shorted and I changed the Pincushion Transistor on the Heatsink and still no change, I am getting 40vdc on the collector pin of the transistor and negligible or non on the other two, can you advised.

Answer:

Try adjust the horizontal size/pincushion setting if have and at the same time see if the base signal of the pincushion transistor change or not. If not changing then probably either there are components already bad or the EEprom ic data have corrupted. Sometimes it can be caused by a defective E/W correction IC.

 

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14 Comments

  1. Amir Mukhtar

    August 21, 2013 at 6:38 pm

    Sir, Jestine from your Permission I do sujjest to check following things in order to repair CRT Pin Cusion problem.
    First of all, there are two type of CRTs Available in market Now a Days. Analogue / Semi Digital and Digital.
    In Semi Digital Pin Cusion problem adjust by VRs except other components. But
    in Digital Pin Cusion mostly adjust by menu setup options and Circuit devices.
    therefore you can below things step wise :

    1. CRT yoke adjustment carbon VRs controls
    2. Section Variables VRs adjustment
    3. low valued Caps in section
    4. driver transistors Or IC controller in Section.
    5. main power Supply for output Voltages

    thanks you
    amir Mukhtar Ashrafi

    Likes(7)Dislikes(1)
    • Jestine Yong

      August 21, 2013 at 8:41 pm

      HI Amir,

      Thanks for adding your tips on this post.

      Jestine

      Likes(1)Dislikes(1)
  2. ZED

    August 23, 2013 at 7:09 pm

    Thanks for sharing it will benefits others.Good and nice tips Amir.

    Zed

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  3. Lawrence Pina

    August 25, 2013 at 7:17 am

    In my experience with CRT computer monitors, pincushion was most often caused by a low value cap with high ESR. Often the bad cap was located right alongside the FBT. Sometimes the case would be discolored.

    Likes(4)Dislikes(3)
    • Jestine Yong

      August 25, 2013 at 8:15 pm

      Hi Lawrence,

      Yes it can be caused by the cap in the horizontal size section.

      Jestine

      Likes(0)Dislikes(0)
  4. jose salceda

    December 13, 2013 at 2:39 pm

    thanks for sharing.,

    Likes(1)Dislikes(0)
  5. malik

    October 26, 2016 at 12:11 am

    i hav sony kv sw29m80

    pin cushion problem

    irf614 short ciruit and L 507 short circuit

    and opne mailer capctor c 567 or c561

    and pin cushion ic njm2903 all parts replac

    no H size controle and E/W CONTROLE

    dispaly owre size corner

    plz help

    Likes(0)Dislikes(0)
    • Jestine Yong

      October 28, 2016 at 10:30 pm

      Hi Malik,

      Did you replace with original L507 coil? How do you check that L507 is short circuit.

      Jestine

      Likes(3)Dislikes(0)
  6. Petes

    September 6, 2017 at 2:17 am

    I have a TV with a spinned image, by that I mean that it's not fully horizontal so that the left part of the screen is a bit higher than the right part of the screen, the problem isn't very big but it's annoying, any idea of what the problem could be? The TV has no adjust potentiometers (or presets).

    Likes(0)Dislikes(0)
    • Jestine Yong

      September 7, 2017 at 4:30 pm

      Hi Petes,

      Do you mean the display tilted one side? If yes then possible the CRT Yoke already loosen and you need to unscrew the yoke and to a manual adjustment.

      Jestine

      Likes(1)Dislikes(1)
  7. Rodskie aboy

    September 7, 2017 at 7:33 pm

    Dear Mr Justine, Seeking help with my Sony TV 25 Inch.. With normal pictures but wave pincussion two side.

    Please help where can i replace the parts and what part it is?

    Thank you,

    Rodskie

    Likes(0)Dislikes(0)
    • Jestine Yong

      September 10, 2017 at 5:15 pm

      Hi Rodskies,
      There are few causes such as low B+ voltage, shorted modulation diode, shorted pincushion transistor, no signal to pincushion transistor. Without hands on assessment, I would not know what is the exact fault.

      Jestine.

      Likes(0)Dislikes(1)
  8. Irfan

    September 12, 2017 at 5:57 pm

    Picture width problem in CRT TV. Its a china tv kit LA76810. No effect in picture by adjusting pincushion variable. No effect from factory setting. What could be the problem. Please guide

    Likes(4)Dislikes(0)
  9. devan naidoo

    June 17, 2018 at 1:57 am

    Hi my sony crt tv kv sw252 has pinchcushion issue .i chked vertical circuit components all seem ok , i changed few caps but still same issue,what else must i check ,thanks.

    Likes(2)Dislikes(0)

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