LCD TVs are todays most trend, and they are invading the electronic entertainment market, ad seems to go further. Here are some faultfinding guidelines; with you can understand the fault to your TV to an extent, provided you must have knowledge in electronics. Sometimes, you may even repair your LCD TV too.
Let us discuss first with its power supply section, which is more venerable to faults.
Symptom: The LED at the front panel of the TV do not light up, even connecting the power cord and switch the TV ON. The unit appears to be Dead condition
There is a relay connected to power supply. It should work [when it works, you can hear a click sound can be heard after the TV is switched ON]. Listen to this click sound.
Check the status of cable connections inside the TV for any loose. Check fuses fitted with power supply regulator board and any other. Check the input voltage at the SMPS [Switched Mode Power Supply] otherwise called as power regulator board. If all these are found OK, and still the set refuses to switch ON the Relay, and no power indicator LED lights up at its front panel, make sure that the main board is faulty. There is no repair to it by replacing components. Replacing it is the only repair work.
Come to other possibilities.
- Is power LED at its front panel is on and the lamp [backlight] is OFF. If NO, check the connections of the power cable and all other cables connected to the power regulator board. If YES, does the power standby DC voltage [5VDC] is present or not. If NO, change the main power assembly.
- If [5VDC] is present, check the main DV voltages [13VDC]. If it is not there, check the associated capacitors, especially check the ceramic capacitors if any connected to this voltage. If there is no fault with any of the associated components, and still there is no 13VDC, the power regulator board is faulty, and should be replaced.
- If this 13VDC is present and there is no main 120VDC present, check all the associated capacitors. If they are also found normal. Power supply regulator board is faulty, and should be replaced.
- If there is 120VDC is present and no 3.3VDC check the regulator IC on the main board, either for open or for loose soldering points at its terminals. Suspect the main boar assembly too in this case.
- Check the voltages at CODEC, 3.3VDC, 8VDC & 9VDC. If these voltages are there or not there, and the set wont switch ON, make sure that the main board is faulty. In rare cases, a well-experienced service technician may set it right. In 90% cases, replacement of the main board is the only remedy.
