Wednesday, August 10, 2016

Understanding and troubleshooting CRT Television Audio circuit

Some times on your line of repair you will encounter a case where a television is brought in for repair with NO audio PICTURE OK symptoms.

Please note that I mean the picture is present and very clear but there is no sound from the speaker. If it is no audio and no picture this is a different case and should be handed on another topic

Below you can see an audio circuit of a television using ic LA4266. Things to look for here include.





a) First be sure the television is not muted via remote control.
b) Set your meter to low ohm and test between the two pins of the speaker. If okay it should have low reading between 4 ohms and 16 ohms.
c) Check the supply to the audio ic is present and if not maybe the ic is shorted or there is an open component on that line. Check back and see what is blocking the voltage. It could be open diode or capacitor shorted to the ground.
d) If the sound is intermittent re solder the actual ic and also the component around this ic.
e) If the above is okay then consider replacing the ic- you should also touch the actual ic with power off and if it is getting very hot then you should replace it directly.

Low audio output from the speaker.
If the output sound is low then it could be the actual ic is faulty or the output
Coupling capacitor has developed high ESR and should be replaced.




Distorted sound from the speaker

If the sound from the speaker is distorted it could be the input coupling capacitor is faulty, speaker paper cone or dry joints on the actual audio ic or the component around it.

Thank you guys

See you in the next class



8 comments:

  1. Good tips,

    Sir one request to you, uploaded circuit diagrams for reference are found Faint on Your Blog .Please upload it with some good resolution.

    ReplyDelete
    Replies
    1. Noted Yogesh, i have tried to improve on that and you can now refresh the page to get the latest upload.
      Again that you for your feedback
      Regards Humphrey

      Delete
    2. Thanks again Sir....Great article!I so mch appreciateD...Very interesting,go0d JOB MR Humphrey!!! Regards MHEL

      Delete
    3. Thanks for your feedback Romel, wishing you all the best.
      Regards Humphrey

      Delete
  2. Sir,
    Still no effect i think photo itself is of low resolution.

    ReplyDelete
    Replies
    1. Hi Yogesh, i noted after uploading new images and doing an update did not pick up new images, so i did a mirror of thes post here.

      http://www.electronicsrepairmadeasy.com/2016/08/understanding-and-troubleshooting-crt_10.html

      copy and past that on your blowser and you will get the updated copy
      Regards Humphrey

      Delete
  3. Thanks Humphrey for that was impressive and informative literature!

    ReplyDelete
    Replies
    1. Thanks and welcome brother Emmanuel,

      Regards Humphrey

      Delete