How to Fix a Dead LG 42LS4600 LED TV

How to Fix a Dead LG 42LS4600 LED TV-Diagnosing and Fixing No Power Issue

An LG LED TV model number was brought to my workshop. This TV was completely dead. There was no red light, i.e., standby light; at first glance, it looked like its power supply was faulty. So I asked the customer where to leave it. I will check it, diagnose its fault, and tell you. After taking your permission, I will fix it. The customer said, “Okay, you keep it and let me fix it.” The customer was a little insistent that you tell me the cost, but I told him, “Sir, you will ask about the cost later because only after diagnosing the fault can I tell you what is wrong with it, what changes will be made, and what parts will be needed.” The customer agreed. He said, “Okay, you work on it.” Most people ask me this question. First, give me an estimate of the cost, but I hesitate a little. I’m doing this because it will cause problems later.

Physical inspection 

I opened this LED TV in my workshop lab and started its physical inspection. In the physical inspection, from the power supply to the main board, I looked at every part carefully and examined it. I checked its capacitors. I did not see any physical damage in them. I checked its resistance. I did not see any sparks or anything on the main board that visually suggested that it might be defective. It was clean. Its power board and main board were both in good condition. So I took it apart. It is necessary for the technician to look at it carefully and do a physical inspection so that if there is any apparent defect in it, he can see it and identify it. The next step is to check its voltage and diagnose the fault. We will proceed step by step.

How to Fix a Dead LG 42LS4600 LED TV
How to Fix a Dead LG 42LS4600 LED TV – No Power Problem Solved

Main board voltage test

I started voltage testing this set; it had 3.3 volts, 1.2 volts was coming, and 2.4 volts was a pass-through. That was also present in this set, and overall all the power supplies were present, but all the power supplies were turning on at the same time. This was a mess in it, and I noticed that the system IC is not resetting; it is not operating properly, due to which all the power supplies are turning on at the same time. This should not happen; it has a sequence. It is calculated that they are turned on; they are power supplies, so now I also decided to check its parts once in detail. Because now all that’s left to do is check the parts: resistors, transistors, and capacitors. We will check these parts in detail, and then we will see if we reach the fund or not.

Fault diagnosis 

Now I started by checking the capacitor first. I checked its capacitors; every capacitor is fine, the electrostatic capacitor and the ceramic capacitor. All these capacitors were fine in their condition. After that, I started checking its resistance very carefully with a multimeter. I started checking its resistance, and then I found that the resistance was bad, whose value was 22 ohms, and this resistance was working as a connection between the NAND flash and the system IC. This resistance was creating a malfunction between the system and the NAND flash, due to which the system was not turning on. I changed this resistance to 22 ohms, then I saw that my set was completely okay; my set was turned on, everything was okay, and the picture and sound started coming perfectly.

How to Fix a Dead LG 42LS4600 LED TV
Faulty 22 ohm resistor in LG 42LS4600 LED TV causing no power issue
  • The LG LED TV was in a completely dead condition when received.
  • All voltage rails tested and found to be OK.
  • A faulty 22-ohm resistor was diagnosed during fault tracing.
  • Replacing the 22-ohm resistor fixed the issue, and the TV powered on successfully.
Conclusion 

In this LG model, we saw that it was dead; we fixed it by changing a resistor, but we had to do a lot of work first to reach this resistance, so if you trace the fault step by step, you can successfully find the fault. You do a physical inspection, check the voltage, then check the components and check the components with great precision. You must have a professional multimeter that can tell you the exact value of the components so that you can get the correct results, as we got with this model. Normally, technicians do not see a slight decrease in value, but the same error occurs. If you know that the value of this resistance is 22 ohms, you check its value on the meter; if it tells you 28 ohms or 33 ohms, then it is bad, and you should replace it. Do it.

Q1: What causes dead condition in LG LED TVs?

A1: If we talk about this case, then there is a malfunction in the system and NAND flash communication due to the 22-ohm resistor.

A2: Power supply failure can also occur. The power supply has two parts; usually one of them can fail. 

A3: There may be a supply line fault in the main board, especially if the three-point-three-volt and one-point-two-volt supplies are not generated. 

A4: If everything is fine, the system IC itself may be damaged, and this could be the main reason.

If you want to read our article on water damage in LED TVs, click here.

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Shaukat Ali - Sony LED TV Technician

Shaukat Ali

Shaukat Ali is a professional Sony LED TV repair technician with over 30 years of experience. He specializes in diagnosing and fixing complex display and board-level faults. Based in Lahore, he shares real-world repair cases to help both customers and fellow technicians.

 

 

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