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Open Winding In Yoke Coils

By on May 19, 2009

pc tube

Well, I’m not sure about you and as for me so far after so many years in this repair line i had only came across only few PC tube that have open winding in yoke coils. It seems that yoke coils are more prone to short circuit compare to open winding. Horizontal yoke coil get shorted easily compare to vertical yoke coil most probably due to stress from the higher voltage and current to the winding. By using a normal ohm meter you could easily check if the winding is open circuit or not. To check for shorted winding in horizontal yoke coil, one have to use a Blue Ring tester.

If either one of the coil have problem (in a color picture tube) the best is to replace the whole picture tube. Yes in fact you can just replace the coil but you have to spend lots of time to adjust the convergence. The display you might get could be color patches all around the tube if you have decided to replace only the yoke coil. I suggest that you replace the pc tube in order to save time.



  1. john preher

    May 20, 2009 at 1:44 am

    I just ordered one of the kits for this tester from anatek last week,I told them that you referred me.I am excited, it will be here thursday.I love getting new test equipment... :)And it is so small, I can easily take it in the field with me.

  2. admin

    May 20, 2009 at 11:15 pm

    Hi John,
    Hope you will enjoy the new equipment.


  3. Hwahwa

    April 7, 2011 at 10:59 pm

    Hi Jestine,
    I have old 17" monitor, the horizontal size became very small to the middle, the vertical seems ok. There is a diode (symbol:->|.->|) attach to heatsink become very hot when turned on.
    -Where should I locate the problem?
    -There are several variable (I don't know are they resistor or capasitor) on the yoke marked Hy,Vy,Dy. What are they for?

  4. admin

    April 8, 2011 at 4:43 am

    HI Hwahwa,

    Those VR on top of CRT is to adjust the convergence. If you case is one horizontal thin line in the middle then check the supply to vertical ic or direct replace the ic and retest.


  5. Amir Mukhtar

    April 8, 2011 at 8:41 pm

    Sir Jestine
    Thanks you for Nice and Valuable information about Yoke Coil Convergence and Shorted winding.

    No doubt, Yoke coil is an important and most necessary part of every CRT based Display. But Time becomes changing because cheap LCD Displays devices in market.

    All in all, thanks for valuable article on CRT YOKE.

    Amir Mukhtar

  6. admin

    April 9, 2011 at 1:14 am

    Hi Amir,

    You are welcome!


  7. Bhoj Raj

    January 27, 2012 at 2:26 am

    thanks sir.

  8. alihsn

    February 22, 2020 at 1:53 am

    mouses has cut the yoke coils. how can i replace with a low cast

    • Jestine Yong

      February 24, 2020 at 9:53 am

      Try rejoin it then apply varnish. If can't rejoin I'm afraid you may need to find another similar one with the same spec for replacement


  9. Islem dz

    March 23, 2024 at 12:45 am

    Is there mercury in this device?


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