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Where To Check For A Very Bright Display Fault In CRT Monitor/TV

By on October 4, 2013


This kind of problem of bright display with flyback lines across screen one has to concentrate on the G2 (screen voltage) and G1 voltage. The G2 voltage has to be within range (typically 250 to 300vdc) and if it set to too high the above symptom will appear.

As for G1 voltage, it should be negative voltage and if you get zero voltage then you can expect the same problem.

In certain designs, a missing dc supply voltage (usually 12 volt) to the video pre amplifier IC also could cause such problem. In rare cases a shorted cathode and the G1 electrode in the picture tube also would cause similar fault. I also have seen a faulty vertical output IC that had caused the above problem.

So there you are, few possibilities of circuits to suspect. Check the circuit one by one and I’m sure you will find where the faulty section/component is.



  1. Zed

    October 5, 2013 at 12:19 pm

    great tips sir. thank you.


    • Jestine Yong

      October 5, 2013 at 8:24 pm

      HI Zed,

      You are welcome!


  2. Waleed Rishmawi

    October 5, 2013 at 8:38 pm

    i had almost the same problem with a JVC tv set. I could see these lines on the screen but also you can see the actual picture. when hitting the tv on the side, the tv comes back normal for a few minutes then the probem startes again. it has to do with cold soldering joints on the ocilator Ic. resolder all the pins of the ic, fixed the problem.

    • Jestine Yong

      October 5, 2013 at 8:54 pm

      HI Waleed,

      Thanks for the comment!


  3. VenuGopal

    October 6, 2013 at 1:51 am

    I faced the same issue several times before,generally this is because of bad capacitor (10mf/250v or similar) in the 200 voltage supply line,which gives power for R,G,B output transistors.

    • Jestine Yong

      October 6, 2013 at 8:14 am

      Hi VenuGopal,

      Thanks for the tip!


  4. raymundo saura

    October 6, 2013 at 9:42 am

    thanks for this kind of articles very informative and it will help me a lot on my coming repairs thanks and GOD bless

  5. Robert

    October 9, 2013 at 1:55 am

    Thanks for the article, Mr. Yong. I don't anticipate working on a CRT TV, but I still find it fascinating and I enjoy learning about them.

    I received my camera yesterday and I'm learning how to use it. I have to learn how to write an article and how to put in the pictures. Is there a good e-book I can buy that teaches how to do that??

    • Jestine Yong

      October 9, 2013 at 10:57 am

      Hi Robert,
      You are welcome. As for putting the photos into the article.It is simple to do it. Once you have taken the photo then download it to your computer. Open up your free microsoft paint and select the photo you want to edit. resize the photo with the function found in the Paint and save it under jpeg file. Now open up your WORD and choose "insert" on top of the page. select the photo you have resized and you are done. Hope this helps.


      • Robert

        October 9, 2013 at 11:52 am

        Hello Mr. Yong. I wrote the article and added some pictures and sent the email but I'm not sure it went through. One of them said your name was not recognized or something like that. If it didn't go through I'll have to find out what is going wrong.

        • Jestine Yong

          October 9, 2013 at 12:40 pm

          HI Robert,

          My email is You can try resend.


          • Robert

            October 10, 2013 at 3:28 am

            Yeah!!!! I think it went through!! 🙂

  6. Amir Mukhtar

    November 10, 2013 at 4:39 am

    Thanks you Sir

    yours Student
    Amir Mukhtar

  7. semmie

    March 23, 2014 at 11:53 pm

    Mr jestine thak you for everythngmi was repear telefunken wat happend is tht I found low voltage in dc emetetly I reliese tht my power supply not active yet so I chngd power regulator then power up again. Thanks a lot urs student semmie

  8. habtamu

    September 17, 2017 at 5:39 pm

    I have sony crt tv with dim display problem. How i can solve the problem?

    • Jestine Yong

      September 21, 2017 at 11:10 am

      Hi Habtamu,

      Dim display can be caused by weak picture tube, low g2 voltage and even low heater voltage.



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