Model: LC-58q620u Turns on with faint display of sharp image. Then image disappears and there is a black screen. It won't allow you to do anything. Can't turn tv off or on after.
This sounds like the set isn't completing the boot leg sequence because of corrupt firmware, either the EEPROM needs replacing, if you have the equipment and know how to solder SMD devices, or the entire main could could be replaced but finding one may not be easy or cheap. One way to confirm this is measure the BL_ON signal, should be around 3 vdc, I think you will find it drops off as the backlights go off meaning the inverter is being shut off because of boot failure
Hello Austin, the image/video disappeared because the TV failed to power on completely. LED TVs are known to have backlight failures and I'm sure your TV has a defective backlight failure.
Jamie, if it was a backlight issue the set would shut off like normal
In some cases, TVs won't shut off normally because the circuitry is detecting some abnormal activities.
Of the thousands of sets we have repaired in our service center I've NEVER seen a set that couldn't be powered off because of backlight failure, the main board has no way of knowing if the backlights are functioning or not, yes it supplies the signal to turn it on or dim the lamps but the processor has no way of knowing if it's actually being done, it just sends the signal to the power supply to enable the inverter section of the power board or dim the lamps, also the power board will never cause a set to not shut off. Look at a flow chart in service lit and it's easier to understand how the sequences work.
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