In this Video we have a 55 inch Vizio Smart/3D television model D55UD1, that when powered on the little white led indicator light at the bottom left corner lites up as though the Television is coming on, however no picture or sound comes up, just a totally black screen.
In this case the problem that we are having are not the Led backlights, but the Mainboard instead. Once the mainboard is receiving the 5V standby from the Power Supply board it is ready to send the PS ON (Power Supply ON) and the BL ON (Backlight ON) voltages as soon as you hit the Power.
But instead, in this case the Mainboard only sends the PS ON voltage back to the power board and not the BL ON/OFF voltage needed to drive the Backlight circuit.
That Backlight On signal/voltage usually is produced right inside the Main Microprocessor Chip on the MainBoard. So we are going to reflow the Main micro IC on the Main board using hot air going back and forth around the IC for approx. 34 minutes at about 400 degrees celsius.
The obvious case is that after years of operation the IC's tend to have some bad solder connections on some of the Pins underneath the chip.

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https://bigdogelectronics.us/

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