Vizio E320_B0E logo flashes then goes dark.

[terryallen44]

Hello all, I got this TV from a friend that was throwing it out but I took it instead.

He advises that it would flash and then the screen would turn off however there was still sound. I was able to duplicate the issue easily.

I do believe it is something with the backlighting or the eeprom. You can turn the TV on under a bright light and see things on the set moving as well as the menus.

I'm not too sure where to go from here. Caps looked good.

Images in album. Sorry. http://imgur.com/a/DDE8H

[Th3_uN1Qu3]

Re: Vizio E320_B0E logo flashes then goes dark.

Backlight issue. Check voltage on pin marked Backlight ON_OFF on the power board, to determine if it is an inverter/LED or main board issue.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

Thank you for replying. I tested the Backlight pin and received a constant 3.3V.

[Hamie]

Re: Vizio E320_B0E logo flashes then goes dark.

So the mainboard is sending the BL-ON signal.
Now check the voltage going to the Leds.

Likelihood you have an open LED. Therefore you won't get backlight untill you repair/replace the strip with the fault.

Big repair If youve never had experience stripping a TV back to the bare bones as the panel will need to come out.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

The LED strips I believe is powered off of the three wires on the powerboard towards the top. Correct?

I see LED1,NC,VOUT.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

Alright, I tested the led connector. Both with it plugged in and unplugged. The TV still powers on without that cable connected. I can't get a reading on this output. Around the same time the back lighting flashes, I see a jump in voltage than it goes back to nothing. (Nothing means random numbers going rampant on the display.)

It does seem to be something on the power board then, if I could externally power the back light I could have a working tv. Not saying I would even attempt that. Just a thought

Note: I have a digital multimeter and I can't get the reading that it peaks at when the screen flashes.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

Bump

[budm]

Re: Vizio E320_B0E logo flashes then goes dark.

So leave the black probe on the chassis, red probe on the LED1 then turn on the TV to see how high the dcv goes up to and goes down to after 5 seconds, then do the same on vout1.
Then remove the LED connector and repeat the same test on that LED connector of the board.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

OK, VOut1 gives me 18.9v and stays there. It jumps up to maybe 70 then levels back to 18.9. Led1 however peaks to 1.3v and rolls off to .2v and that's really about it. Attached and unattached wire reads the same. I noticed that led1 goes into a SOT-223 MOSFET? Not sure how I would test that.

[terryallen44]

Re: Vizio E320_B0E logo flashes then goes dark.

I tested the MOSFET N gate with data sheet providing pins.

This is odd though.

Source Voltage: 0.3mV
Drain Voltage: 1.60v
Gate Voltage: .8mV