Chosen Solution
My TV turn black with no sound or picture. The power light is on. I openness the back cover and it seems all capacitor are in working order. Do I need to replace the BU board or power supply
jpwinarto this sounds more like a power board issues. You do want to start by checking the power board voltages. Post some images of your boards with your question by using this guide. There are two different power boards depending on the type of LED backlight.
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check the connector (red rectangle) to see if you get those voltages: 1 Power on 2 20V (24V) 3 20V (24V) 4 20V (24V) 5 GND 6 GND 7 GND 8 GND 9 3.5V 10 3.5V 11 3.5V 12 3.5V 13 GND 14 GND 15 GND 16 GND 17 12V 18 Inverter On/off 19 12V 20 Lamp : A-Dim LED : N.C 21 12V 22 PWM Dim #1 23 NC 24 Error-out.
Hi. I had the same trouble on a 42LX6500. TV powers on, but no video, backlight or sound. Nothing. Checked voltages and power-on signal as explained by oldturkey03 but voltages were correct. So, I decided to reflow LGE3556C under brown heatsink and it is working now. A professional reballing should solve this definitely.
The heat cause the chip to seat to the board, giving it the contact it needs. When the chip was not properly seated when first placed over time heat will cause them the separate. The key is not to apply to much heat or you will damage the chip. Follow the simple quick fix and you should be enjoying your TV for many more years to come.
