How To Repair No Sound Problem in Sansui Hi-Fi
Customer sent to me this Sansui Hi-Fi with the complaint of no sound even though the volume control already set to maximum. The first thing I did was to connect an external speaker (see photo below) to the audio output at the back of the hi-fi to check if there is any sound coming out from the output jack.
There was no sound at all and I need to open up the cover and check for any bad components in the audio output circuit.
Once the cover was opened I straight went to see the mainboard audio section to see if there is any broken tracks, loosen connectors, bulged electrolytic capacitors and etc.
They were all good thus I had to perform the DC supply test to the two main amplifier ICs. See the photo of the two arrows were pointing to the two main amplifier output ICs. The DC supply found to be good.
The next test was to check on the DC supply to the digital controlled stereo audio processor TDA7318D.
Below is the link of the TDA7318D Audio Processor IC:
The DC supply test was checked to be good. If you read the IC description it says that the IC has volume control, tone (base and treble) balance (left/right) and fader (front/rear) processor for quality audio applications in car radio and Hi-Fi systems. This means this IC controls lots of function that is related to audio. Since the DC supply was tested good, I directly replaced the IC with a new one and retested it.
I was right by simply replacing with a new IC , the sound came back to life again. Again I can use oscilloscope to check for the audio output signal but replacing the audio processor IC directly is much faster.
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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Note: You may check out previous post about fixing active speaker in the below link: