Fix TCL TV Black Screen Issue L43S6500
A TCL L43S6500 LED TV was brought to me for repair with a no display issue. The screen was completely black, but after 10-12 minutes, the sound started playing, indicating that the main board was working fine. Upon diagnosis, I found that the issue was in the T-Con board. I informed the customer and proceeded with the repair.
Fault Overview
When I turned on this TV, it would show a normal picture for the first ten or twelve minutes, then the screen would go completely black. When I turned it off and turned it on a little later, its screen time decreased even more. From its condition, I guessed that some part inside the T-con board was overheating and causing a malfunction. I opened the back cover of the TV in the workshop lab and analyzed the fault. The voltages of its T-con board were not correct, so I decided that its T-con board was faulty. Now either I would replace it or repair it. I decided to repair it. Let’s repair it step by step.
Fault Finding
T430HVN01.A
This circuit uses a DC to DC IC number P303-11. I first checked its voltage.
- VDD-3.3 V is the normal range.
- AVDD-16 V is the normal range.
- VGL-7.6 Minus Volte Are Present.
- VGH-16V They were abnormal.
Fault diagnosis
I turned on the TV and tested the voltage of the T-con circuit. Its AVDD, 16 volts, and VGH voltages were also the same. While the VGH voltage is double the AVDD voltage, these volts are much lower? and after being on for a while, these voltages suddenly disappeared. I changed its DC to DC IC, but the fault still existed. Now I tested its resistance carefully. All the resistors were in good condition. I even checked them by disconnecting them from the circuit. There was a MOSFET on the AVDD track; this MOSFET was switching sixteen volts. In a fault condition, this P-type MOSFET would slowly reduce the voltage. Due to which the VGH voltage, which was already low, reached the zero point. I replaced this P-type MOSFET and test-ran the TV, and my fault was completely corrected. All voltages were absolutely correct.
Fault-finding image
I have also included a photo with this article to explain the fault, which shows the fault area and the faulty part No: Q202 P-Type MOSFET.
Conclusion
In this case, there was a technical fault regarding screen repair, which we repaired at the chip level. In my opinion, replacing the entire board in LED TV repair is not a miracle. A good technician can get to the root of the fault and fix it. You are requested to write your suggestions in the comment section so that I can write better fault-finding articles in light of your feedback. Please share this article with your fellow technician friends as well.
Sony LED TV Repair Center Lahore
We repair Sony LED TVs at the chip level. If you have any problems with your TV, please contact us.
- power supply repair.
- backlight-repair.
- screen repair.
- main board repair.
- t-con repair.
- HDMI connectivity repair.
- Sound problem repair.