Friday, July 17, 2015


A colleague of mine had a friend who wanted her television checked by a technician and he asked me if I can help her friend sort out the audio problem with her television

I fixed a date and off we went on site with him as my tour guide, I carried with me my usual minimum tools to help me with this assignment.

We found the television ON and the kid was watching the screen although there was no audio and I think this was good enough for a two year kid.

Looking at the screen I noticed the screen had some waves kind of across the screen and I thought to myself…even if I solve the audio problem there is yet another problem with this set and to me this pointed to faulty filter capacitors.

This also led to conclude that maybe if the hypothesis is right and I get faulty capacitor and replace it this could also solve the sound problem assuming that the capacitor also filter the supply to the audio circuit.

I opened the set and scanned around the board looking for any bulged capacitor and I only found a few medium sized capacitors all tested okay to my ESR meter.

The motherboard was too small and I was wondering where is the power supply section, only to realize that actually the TV was using power adapter.

I did not notice when the TV was brought to the table the adapter was left behind. I asked for the power adapter and did voltage testing across the output connector. See the figure below on how to test.

Please note this is not me testing and I just shared this for educational purpose only.

Usually the output is DC and therefore the meter should be set to DC mode, upon testing the output I got a 12.25 Volts and I said YES!...I have got the culprit…the power supply is faulty.

To be sure I decided to confirm if this is the expected output for this adapter and since the TV has no circuit diagram whatsoever, I decided to confirm with the input on the TV body where the adapter is connected and to my surprise It was written 12 volts and that means my hypothesis was wrong and this also gave the power supply a clean bill of health (you can also find the voltage out printed on the adapter body)

With that I decided to change my line of thought and this time decided to check the connection to the speaker and this also seemed okay as far as my eyes were concerned.

I pulled my meter and tested across the speaker connection in circuit and for one speaker I got 6 ohms and I had no problem with that.

Testing the next speaker I noticed it was reading high and kept on changing and I decided to cut one wire to isolate it out of circuit and testing across the two pins I got open circuit.

After that I decided to see the effect on that to the TV and therefore applied the power and to my surprise the audio was back and very clear.

I really don't know what caused the audio to disappear completely after failure of one speaker unless if the other speaker had intermittent problem.
That’s all for now guys
Stay safe
Humphrey Kimathi


  1. Hi Martin,
    Good question, the wavy lines disappeared miraculously ...hahaheheee.
    Regards Humphrey

  2. hello Humphrey,
    greeting from me!
    i am a regular reader of you post.\
    would you share a solution about retrace line fault because i am found a dramatic case in chaina hongdy chassis which is at few days at cold condition tv set starting at colour fault after half an hour the problem was automatically solved.
    i am check AKB line,RGB,system ic side and also base ckt, its seems to me okay.
    would you please feedback very quickly about this problem.
    also i am a regular fan of your post.

    1. Hi Alo-Adher,
      Thanks for your feedback, check out this link for more info on causes of retrace line in CRT television

      regards Humphrey