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