Power Supply Fault in TCL L32D2900 – TP.MS1306.PB778

TCL L32D2900 Power Supply Repair Guide: Learn how to fix this fault step by step. When this set came to me, it was completely off. Its red light was off. The power supply was in a dead condition. In this fault-finding guide, we will write the complete details of how to fix it. On initial testing of the main board, it was found that the fuse is fine and 300V DC is being generated.

Fault Diagnosis – TP.MS1306.PB778

When I first looked at the main board, I saw that its TL431 IC was blasted and the related resistors were also 2.2K blasted. As a precaution, I connected an external 12V power supply to this main board so that I could confirm the next circuit. When this voltage was applied, the system IC became operational and the standby light would turn on.

Component-Level Fault Details

This power supply circuit has an OB2273 IC, and as we have mentioned earlier, its main DC voltage was being generated on the main capacitor. I checked the short circuit on the VCC pin of the UB101 IC, and the reading here was normal. A ceramic capacitor on pin number 3 of this IC was showing a short circuit to ground. I changed the IC, and the short circuit here was gone.

TL431 IC-Related Repair Work

Now let’s come to its feedback circuit. This circuit includes a TL431 optocoupler and a voltage divider resistor connected to the reference pin of the TL431 shunt diode. You can see in the picture that its TL431 was blown. I replaced it, also replaced the optocoupler, and also replaced the 2.2K resistor. The voltage divider resistors were fine; their values are in the picture.

• Faulty power supply: dead, no standby light.
• Fuse in good condition.
• Main bridge rectifier is perfect with no shortage.
• Main DC voltage in correct condition.
• Pin number three of the main IC is shorted to ground.
• Main IC OB2273 changed because its RT pin was shorted to ground.
• TL431 It was a blast; it was changed. 
• The optocoupler was also faulty; a new one was installed. 
• The 2.2K resistor providing the 12-volt supply to the optocoupler was blown and replaced. 
• This fixed my fault after changing everything. 

Expert Insight – TCL L32D2900 Power Supply

In this case, my opinion is that this fault was created internally because if there was a voltage spike behind it, the fuse would have opened or the main rectifier would have been damaged. In my opinion, its feedback circuit has been disturbed, and due to this, the main IC may have also been damaged. The cause of this fault is the TL431 shunt diode.

Customer Care Tips for TCL L32D2900

I always advise customers to install a voltage protector of good standard to protect their LED TV from electric spikes and, secondly, install a quality cable protector to protect the cable. These two things protect your TV to a great extent from external electric shock, and another very bad reason is the corrosion effect, which affects the PCB of your TV.

Conclusion

TCL L32D2900 Power Supply Repair Guide: You have seen how we fixed this power supply fault step by step. This is a complete guide. We have also included pictures in it, which will help you in diagnosing this fault. Sony LED TV Repair Center Lahore promises to keep sharing the perfect fault solution with you, like this TCL L32D2900 Power Supply Repair Guide.

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