Philips Logo Flashes, Then Turns Off

I attached a bunch of pictures of the TV to the OP. When checking voltages more carefully this time I realized a lot of them fluctuated. On the power board the 5v, 20v and GND rails were all showing the correct readings. The RES, ADJ, and BL rails would be around 280mv until I pressed the on button, then they would shoot up to 3.3v. Note that the ADJ and BL voltages would be zero when the main board was unplugged from the power board.

The LED Driver was also fluctuating and very confusing to me. The LED 1, LED 2, LED 3, and LED 4 rails would go from 66mv to 0.6v and then shoot up to as high as 50v for a split second when I pressed the on button, but go back down quickly. I'm assuming that quick spike correlates the the Philips logo flashing on the screen for a split second. The NC rails went from 7.7mv to 11mv. The FB rails all read zero. Note that these reading would all go away if I unplugged the main board from the power board even though the LED Driver is on the power board.

The main board doesn't have any indicators by the connector that comes from the power board, but from top to bottom the road like this: zero, 289mv that would shoot up to 3.3v when pressing the power button, zero, zero, zero, 20v, 20v, 20v, 20v, zero, zero, zero, 5v, 3.3v

The connector to the left speaker read 3.3v, zero.

The connector to the right speaker read zero, 41mv, 41mv, zero

The connector to the standby light that never turn on is, from top to bottom, 3.3v, zero, 3.3v.

Note that the picture of the main board shows the digital audio output port lit up red. That turns off after a few second. Also note that every once in a while when I press the power button I will hear a very noticeable buz and high pitch noise coming from both speakers that won't go away until I unplug the tv, but it's random and doesn't happen very often. Let me know if you need any more info. Thanks!

@rohansolo does this "up to as high as 50v for a split second when I pressed the on button, but go back down quickly" change when you unplug the backlights from the power board?

Yes, when unplugged from the power board LED 1 and LED 3 would only go up to 0.66v after pressing the on button. LED 2 and LED 4 would go up to about 380mv when pressing the on button.

@rohansolo with the backlight connected again etc. Turn your TV on and measure the voltage on the fuse of the T-con board. So far, all measurements were made in DC mode, correct?

@blainetaylor looks like superficial corrosion. Whats on the other side of that board (same location)?

Didn't matter the new board i bought didn't help either.

@blainetaylor if you are thinking of changing the backlights I would suggest getting two bug suction cups with handles the help lift the panel. It was actually quite easy, but nerve racking. I placed a couple towels down and put the panel on the towels.

I fixed this tv August 16, 2023.

Its doing the same thing it did when i replaced the backlights. Lasted more then a year. Thinking of replacing them again.