Vizio LCD E420VO 2 seconds to black

[Cosmo66]

I have 5 volts standby present. When I press power button, PS_ON goes to 2.98 volts, backlights come on, screen displays Vizio logo for about 2 seconds, then the power supply shuts off and the TV goes back into standby.

It appears that this power supply is a power supply/inverter board in one, and the main board is a main/tcon in one board.

I see no bad caps or signs of anything bad on either board. I am suspicious of the main/tcon board. How can I verify the power supply is good? What other signal is it getting from the main that might make it shut off?

[JonathanAnon]

Re: Vizio LCD E420VO 2 seconds to black

The inverter board may be shutting down because of a shorted transformer or IC on the inverter board... do you still hear audio when the video shuts down?

[Cosmo66]

Re: Vizio LCD E420VO 2 seconds to black

no audio. I tried to plug in a dvd player to check this. The TV turns on, displays the Vizio splash screen, and then shuts off before I can get to any menus or change inputs.

This is why I'm a bit suspicious of the main board. I'm thinking possibly corrupt eeprom or something like that maybe shutting down the power supply after the splash screen.

If I hold 3 volts on the PS_ON, shouldn't the power supply stay on if it's good?

[Cosmo66]

Re: Vizio LCD E420VO 2 seconds to black

*bump*

I want to power up the power supply without the main attached. What would be the best way to do this?

[HiLite]

Re: Vizio LCD E420VO 2 seconds to black

Was this problem ever resolved? If so what was the resolution?

[budm]

Re: Vizio LCD E420VO 2 seconds to black

Yes, you can force on the power supply by using 1 K resistor between the PS_ON pin and the 5VSTBY pin, BUT you have to make sure to disconnect the cable on the PS_ON pin that goes back to the main board because the main board will try to keep that line low.

[HiLite]

Re: Vizio LCD E420VO 2 seconds to black

Yes, you can force on the power supply by using 1 K resistor between the PS_ON pin and the 5VSTBY pin, BUT you have to make sure to disconnect the cable on the PS_ON pin that goes back to the main board because the main board will try to keep that line low.

I went ahead and replaced the power board and problem remains. That leaves the main board, but I can't find it anywhere everyone is out of stock.

EV420VO
3642-0972-0150(4E)
CSD: 3642-097209395

[HiLite]

Re: Vizio LCD E420VO 2 seconds to black

I now have replaced the main power and previously replaced the power board but problem remains. Vizio logo on frame has a Amber light, turn on the tv the Amber light turns white and Vizio appears on the screen, 2 seconds later the tv turns off and the light on the frame goes Amber again as if in standby.

HELP!

[budm]

Re: Vizio LCD E420VO 2 seconds to black

But did you try forcing on the power supply board to find out if power board is OK as suggested in post 6?