Needing confirmation Vizio E701i-A3

[sbeck]

Working on this for a friend.

Tv will power up, LED backlight will flash on for a tenth of a second then stay off, if I shine a flashlight in the front of the panel the display is working, just no back light.

I have tested power going from the power supply to the LEDs, but it is there only for that flash, then voltmeter reads zero.

I theorize this means something on the power supply board has gone bad. Just looking for confirmation from some one who knows a little more.

Thanks S

[tom66]

Re: Needing confirmation Vizio E701i-A3

There's probably a signal like BLON or LED_ON, check this. If this signal is disappearing when the LEDs go out, I'd look at the main board. But if it stays on then I'd look at the power supply.

[sbeck]

Re: Needing confirmation Vizio E701i-A3

Thanks tom66,

I tested LEDON coming from main board to power supply, and have 3.3VDC, But still nothing on the LED+ going from power supply to LEDs.

It seems no parts stores, online or otherwise, that I have contacted can get this board, how would I go about diagnosing the components of the board, is there a starting spot? Or do you have another option for a replacement? The number on the board is 1p-1129800-1011.

Thanks again for the confirmation.

S

[martyparish]

Re: Needing confirmation Vizio E701i-A3

You may be able to repair the PSU. Please post clear high resolution photos of the PSU for starters. A shot of the whole chassis would be great too.

[sbeck]

Re: Needing confirmation Vizio E701i-A3

Thanks,
The TV is so big, its hard to get the whole chasis in there, but if you need better, let me know. Also the Power supply board is large too, so if you need a better spot on it, let me know.

S

[ecking767]

Re: Needing confirmation Vizio E701i-A3

Thanks,
The TV is so big, its hard to get the whole chasis in there, but if you need better, let me know. Also the Power supply board is large too, so if you need a better spot on it, let me know.

S

good pictures

[martyparish]

Re: Needing confirmation Vizio E701i-A3

Pics look good! To get more info, please test all pins on the same connector with LEDON and list all results.

eg.

T CON_ON: 3.3v
12v T CON: 12.2v
etc...

[sbeck]

Re: Needing confirmation Vizio E701i-A3

Top to bottom Tested to chassis ground
tcon_on: 3.25
12V T Con: 12.52
-
LED-BR: 2.72
LED ON: 3.33
BL ERR:-
12V reg: 12.52
12V reg: 12.52
-
-
-
12V Audio: 12.52
PS ON: 3.33
AC-DET: 3.49
3.3V: 3.36

[tom66]

Re: Needing confirmation Vizio E701i-A3

And here I thought this was a 17", not a 70"! Blimey... that's very little for a 70" TV... I'm guessing it uses a Sharp panel, as Sharp are currently leading the field in big screen TV (especially LED backlit.)

[sbeck]

Re: Needing confirmation Vizio E701i-A3

yes, it does have a sharp panel

[tom66]

Re: Needing confirmation Vizio E701i-A3

So, when it fires up, what do you measure across LED1+ and LED1-? No probe should be on the chassis.

[sbeck]

Re: Needing confirmation Vizio E701i-A3

12V for a flash. I am using a digital meter, and it takes a bit for it to register, so I don't know exact.

[tom66]

Re: Needing confirmation Vizio E701i-A3

12V is far too low -- I'd expect hundreds of volts.

[sbeck]

Re: Needing confirmation Vizio E701i-A3

12V is far too low -- I'd expect hundreds of volts.

It certainly could be, like I said it is there and just as quick it is gone.The LED's do flash on fully for that split second as well

[tom66]

Re: Needing confirmation Vizio E701i-A3

The LED ON signal is on continuously?
Can you remove the power board and get a picture of the underside?

[sbeck]

Re: Needing confirmation Vizio E701i-A3

Yes while the set is on it has the 3 volts on LED_on

In the pictures, top is still top I have flipped it left to right

[budm]

Re: Needing confirmation Vizio E701i-A3

From looking at the outputs that go to the LEDS, it looks like it will not be steady DC but pulsing DC output at high frequency with pulse width modulation. So if you use DC meter to read those outputs, it will not show correct DC voltge.

[sbeck]

Re: Needing confirmation Vizio E701i-A3

What do I need to do to get you what you need?

[budm]

Re: Needing confirmation Vizio E701i-A3

Can you check the resistance between the backlights LED connectors' pins (unplug the connectors from the power supply board) and the chassis ground to see if it shows any reading?

[sbeck]

Re: Needing confirmation Vizio E701i-A3

It all shows infinite ohms between each other as well as each pin to chassis ground