Vizio E7-E3 Black Screen

[BobbyG58]

Re: Vizio E7-E3 Black Screen

https://www.badcaps.net/forum/attach...5&d=1545151445
The LED connector (the one on the left in the picture), how many red wires and Black wires? I expect to see Voltages on the red wires, if I am correct, all the red wires should be all tied together to feed the + Voltage to the LED strip's Anode.

Hi Bud, well let me get you the all the voltages
On the PSB with unit ON

1 VSNS= 2.4
Pins 2-5 LED_Out = 57.0
6-10 GND= 0
11 +16v=16.2
12 AC_Det=3.9
13 PS_ON=4.9
14+ 16V= 16.2
15+ 16V=16.2

Powered Off:
1=0
2-5=0
6-10=0
11= 16.2
12= 3.9
13=0
14=16.2
15=16.2

On the Main Board LED Connector there are 6 red=57V and 12 Black=0V

One other thing I noticed and maybe it is just this Model, but when powered on with one press, the standby light lights for a couple seconds and goes out but the unit remains on.
Second press and the standby light comes on and then shuts the unit down.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Maybe try unplug powerboard from backlights, see if the filter cap voltages go above 279.

[BobbyG58]

Re: Vizio E7-E3 Black Screen

Maybe try unplug powerboard from backlights, see if the filter cap voltages go above 279.

Do you mean unplug C201 from PSB to Main Board and check?

[nomoresonys]

Re: Vizio E7-E3 Black Screen

.

[BobbyG58]

Re: Vizio E7-E3 Black Screen

.

There is only one connector going out from the PSB.
On the Main Board there is one going to LEDs, one going to the T-Con The one for standby/ menu/volume board and one for audio
and the VSNS ribbon.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

My bad, meant to say the one from the mainboard going to the backlights.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Whenever plug or unplug any cables n such, do it with tv unplugged then plug in after cable removed, less chance of shorting something out that way.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Wonder if theres a service manual for this one available.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

A little testing here. https://www.youtube.com/watch?v=4cUeD0E0jqI

[BobbyG58]

Re: Vizio E7-E3 Black Screen

Maybe try unplug powerboard from backlights, see if the filter cap voltages go above 279.

No change in voltage with LED connector unplugged from Main Board.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Ok, do you have voltage at the test point on the connector going to the backlights, like in the sj video in post #29?

[BobbyG58]

Re: Vizio E7-E3 Black Screen

Ok, do you have voltage at the test point on the connector going to the backlights, like in the sj video in post #29?

I have 57v on the Red Wires and 0v on the black wires.

I did not recheck the voltage on that connector with the LEDs unplugged.

After watching a SJ video on this unit, there are 6 rows of LEDs which would coincide with the 6 Red leads and the 12 black leads. 1-Red and 2-Black for each Row.

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Watch that video a few times, I think the answer is there, if all that tests good, thinking a bad backlight led situation or leds themselves bad or bad connection in backlights, dont know what could be left.

[BobbyG58]

Re: Vizio E7-E3 Black Screen

Watch that video a few times, I think the answer is there, if all that tests good, thinking a bad backlight led situation or leds themselves bad or bad connection in backlights, dont know what could be left.

I have a question about the LED circuit. Why are there 2 ground/ black going from the MB to the LED circuit? What is the purpose of the 2nd GND/ Black?

[budm]

Re: Vizio E7-E3 Black Screen

I have a question about the LED circuit. Why are there 2 ground/ black going from the MB to the LED circuit? What is the purpose of the 2nd GND/ Black?

You have 12 LED strings that is why there are 12 Black wires for the Cathode return for each LED string and 12 PWM Controlled power MOSFET's to maintain constant current for each LED string.
There must be common failure that cause all 12 LED string not to flash on at all, it is almost impossible to 12 failed LED strings. You can have one or two fail LED strings but the good one should at least flash on and then the protection circuit kicks in due to bad LED string.
I still wonder about the PFC Voltage which not at typical value of 380 ~ 400VDC range.

[BobbyG58]

Re: Vizio E7-E3 Black Screen

You have 12 LED strings that is why there are 12 Black wires for the Cathode return for each LED string and 12 PWM Controlled power MOSFET's to maintain constant current for each LED string.
There must be common failure that cause all 12 LED string not to flash on at all, it is almost impossible to 12 failed LED strings. You can have one or two fail LED strings but the good one should at least flash on and then the protection circuit kicks in due to bad LED string.
I still wonder about the PFC Voltage which not at typical value of 380 ~ 400VDC range.

The 12 strings goes with the video I watched. 2 wide and 6 rows. 3.1v x 18= 55.8v or the 57v on the LED side.
So if I understand correctly, you are leaning the same way nomoresonys is leaning. A bad power supply board/ component? If so would the symptom of half the screen black first followed later by both sides be the same result of this PSB/ component?

[budm]

Re: Vizio E7-E3 Black Screen

Do you have LCD panel model number?

[BobbyG58]

Re: Vizio E7-E3 Black Screen

Do you have LCD panel model number?

Sorry, No I don't have the panel number. Is that on the chassis somewhere?

I am thinking about the 380-400v caps PFC.

If one went bad would that take half the screen and then the second failed taking the rest of the screen?

BTW thanks to both of you for taking the time to walk me through this.

[budm]

Re: Vizio E7-E3 Black Screen

1) So I look at the SJ video, each LED string has 9 LED's, two LED strings are connected together so both strings use 1 common red wire and two black return wires, one for each string, that is why you have total 6 red wires and 12 Black wires.
So if they are 3V LED, then total Vf (Forward Voltage for each string will be about 3V x 9 LED's = 27V, if they are 6V LED's then total Vf for each string will be 6 x 9 = 54V.
You indicated that you do have 57V feeding the Anode of each LED string so I expect to see Voltage at the Black return wire of the LED string, but you indicated all 0V which does not make sense that all 12 LED strings went open circuit.

2) About the two main filter caps that shows about 300VDC instead of typical 380 ~ 400 VDC, those two caps are connected in parallel, so that will not be the cause of the half screen problem.

3) Your LCD panel looks to be made by Sharp, and these Sharp LCD used in many 70" TV's and typical failure is due to side tab driver, which based on your prescription about half screen is dark seems to point to the problem on the panel, the T-CON on this TV also controls the backlights so you may want to try disconnecting those 4 flat ribbon cables between T-CON and the LCD panel to see what happen. It may be that the T-CON is locking down the backlights circuit. BTW, when you say half screen is dark, is it like completely black? Or something like this: https://www.reddit.com/r/VizioTV/com...n_vizio_e70e3/

4) The main board IC U400 is the LED driver, what is the P/N of that IC?

[nomoresonys]

Re: Vizio E7-E3 Black Screen

Maybe check those little capacitors on tcon for shorts, diode mode, probe on each side, tv unplugged.