Cause of Sound Problem in Sony KLV-40S400A

Sony Bravia KLV-40S400A Sound Problem This LCD TV came to me for repair due to a sound-related fault. Its sound suddenly became louder, and there was noise. The customer said that earlier this fault used to occur occasionally, but now it is constantly spoiling the sound. Since it is an old model Sony TV, I think the fault must be in its main board. I took some time from the customer and said that I will first tell you after diagnosing it, and then with your permission, I will fix it.

How to Repair Sound Problem from Main Board

I opened this set in the workshop lab and first checked its speakers, which were completely accurate. Anyway, my experience is that the speakers of this model are very rarely faulty. Now I checked the VCC voltage of the audio amplifier IC in its main board, which should have been 12V. These were also fine. The source connection of the audio amplifier IC and the digital signal was also fine. Now I decided to check the system IC. There is a heat sink on it. After removing it, I checked the array resistance connecting its RAM to the system. Here I found a resistor fault of 33 ohms.

Malfunction system to RAM IC 

In this model, the RAM is external to the system. This system IC works with two RAMs. Array resistors are used here for the connection between the system IC and these two RAMs. Due to the damage of these resistors, many faults can appear, for example, lines in the pictures, the set going into a total dead condition, or sound problems. Well, in this case, we are only facing the sound, so I am attaching the pictures of the array resistors that I changed. After changing this 33-ohm, I installed its heat sink and turned on the set, so my sound fault was fixed.

• The fault sound suddenly became loud and noisy.
• Malfunction between system IC and RAM 
• Here 33 Ohms was faulty. 
• 33 If the ohms array resistors are changed, the fault is fixed. 

Final Check after Main Board Repair

Now comes the final testing phase because after fixing faults that sometimes occur and sometimes do not, it is necessary to run the LED TV on a test run to be satisfied that the fault has really been fixed. I fitted the set completely and turned it on for about three to four hours and tested the sound. Its sound fault had been properly resolved. After that, I informed the customer that his TV has been repaired and he can take it. When he came to pick up the set, I also told him that he would give me a report on it after running it for a week.

Conclusion 

Sony Bravia KLV-40S400A Sound Problem You saw how we diagnosed and fixed this fault. Due to RAM to system malfunction, the sound suddenly became louder, and there was a lot of noise. Sony LED Repair Center tries to provide you with any chip-level repair in the form of an article so that if any fellow technician is facing this problem, it will be easy for him. If you have any questions, you can ask in the comment box and I will answer you.

Q&A

1.Why is my Sony Bravia TV producing distorted or crackling sound?

This fault may be caused by a speaker fault or a problem in the circuit. 

2.What to check when Sony Bravia has loud noise in audio?

Malfunction system IC to RAM.

3.How to fix audio distortion from main board in Sony Bravia?

Check the source signal of the audio amplifier to see if it is connected to the system.

4.Why does Sony Bravia sound suddenly become very loud or noisy?

Sam has written this article on this very fault, you should read it in detail. 

For a detailed guide, read our article on Sony KDL-40CX520 2 Blink Error Solution.

For detailed COF pinout and technical data of NT39563H-C6502, check out this complete guide.

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