Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Press power button to turn TV on and get 3.2v that is.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Each X fault pin reads 3.1/3.2 volts weather back lights on or off. In fact when I plug TV in I get 3.2v power lite is on and when it fades and goes out than 3.2v drops to 0v. Press power button and get 3.2v.

[budm]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Ut oh... got to quite over here. Budm any thoughts on these led control chips? Like where to start, what portion makes lights dimm?

I would monitor the X fault pin on each one of the LED Controller IC you will need to leave black probe on the chassis and red probe on each LED controller IC X fault pin then turn on the TV to see what happen when the backlights come on and the go black, then turn the TV off and move the red probe to the next IC and turn the TV on and look at the Voltage. Do the same on the rest of the LED controller.
We need to see if that is why the backlights come on and then go off due to fault detection or not.
I believe it will go low when fault is detected.

[triplefour]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

i havent given up, but im working on other TV's at the same time. will definitely post updates on this one's progress if i make any.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Like i said instead of lights dimming down, screen just go's black at the point instead of being dim for normal screen view.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Ut oh... got to quite over here. Budm any thoughts on these led control chips? Like where to start, what portion makes lights dimm?

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Hope not, its a pain... Royal pain...

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Not sure where to start on these. It does mention being tied to transistors but their is none only on power board. Not sure yet what the 6 legged IC's are yet unless they are being used as transistors. All resistors that are in a row on all 4 circuits are according to my meter sounding off on either side of them in diode mode they are in ground rail. And the package has a fault sense for a short or open circuit.

[budm]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

BTW, I do have this Vizio in the validation lab that I use everyday, hopefully it does not go out yet.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

That it is. Very complex.

[budm]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Found this link that gave more info on chip..

I am glad you found the spec sheet. the dialog web site does not provide info until you create user name and pass word.
It is complex LED driver chip.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

The LED driver IC's U801 through U804 he used U301 as an example on what to look for. The part numbers that i gave are to the 4 buck converters IC's at connector to main board.

[triplefour]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

can we confirm which chips we're talking about here guys? bud asked for U301, but i didnt find that on the driver board so i posted what i thought he meant, (or thought he saw) at U804 ( there is a U801 and 8 can look like a 3 if its blurry enough)
which location are you referring to, AL?

if there was an IRC channel for this forum i'd be idle in it 24/7

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Found this link that gave more info on chip..

[budm]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Budm the chip numbers are:1Z690l2 and ZA4S16. Look for data sheet could not find by either number.

Your P/N is not same tripefour in post 73
https://www.dialog-semiconductor.com/products/as3820

[budm]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

i know it doesnt apply to my problem (yet) but im happy to help
i think i see
AS3820E H
1421XBC

https://www.dialog-semiconductor.com/products/as3820

[triplefour]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

al1415 thanks, so i guess the enable pin DOES have to be on..as well as the SS
im thinking those voltages must come from the mainboard and correspond to the 2 im missing on CN805

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Budm the chip numbers are:1Z690l2 and ZA4S16. Look for data sheet could not find by either number.

[al1415]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

R8219=4.1
c8067=1.8

[triplefour]

Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

al1415 could you verify the voltage you have on the ENable pin (pin2) of IC804? easiest way to get is to measure either side of R8219
and also if you can, the voltage on C8067 (which is connected to the SS pin)
just to see how this IC is actually working, if i am supposed to have voltage at the enable pin for "normal" operation.
thank you