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

I have not had the time to work on this project and since I puruze these forms quit a bit I am going to upload the service manual and maybe somebody here can take the time to figure out why back lights go out and screen goes black. I have changed out the part that my leek seeker said was bad but no difference or change. Logo shows up than screen goes black, in other words back lights come on than go out.

[triplefour]

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

thank you. i havent had much time lately either but i still have this tv in storage and will get back to it eventually.

[ARGO]

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

Thanks, al1415 for manual.
I have the same TV and the problem is not solved.
My opinion, the booting problem maybe cause by fail of light sensor that located on IR board. The light sensor has I2C interface and CPU reads it...
If somebody will be able to disconnect IR board on working TV to see what happence without it would be perfect.

[Cwood]

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

Has anyone figured out the problem with this tv? I've changed the eprom on the main board, purchased a new main board and a new driver board and still no change. Any help would be greatly appreciated.

[ARGO]

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

Has anyone figured out the problem with this tv? I've changed the eprom on the main board, purchased a new main board and a new driver board and still no change. Any help would be greatly appreciated.

I don’t.
As I wrote, it may be the problem in light sensor. But I don’t have any to check.

[triplefour]

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

sorry this tv is in storage somewhere ever since i had to move. i hope i will get back to it someday because it is a nice tv! for now though im working on other tvs. if you can, please help me along with this one?
https://www.badcaps.net/forum/showthread.php?t=72716
thank you1

[cooper trace]

Ok so I had the exact same problem as triplefour and midnight . Voltages were the same too . Figured it was the main board as the problem . When I removed all of the cables and unscrewed the board from mount I noticed the pads on the bottom side were really stuck to the metal frame . Upon further inspection I noticed the pads on bottom side had somewhat liquidfied. So I totally removed the pads from the board and used a microfiber cloth to get the sticky residue off the board . There were two pads and both had the same problem . I then proceeded to use my heat gun to dry the board . About three minutes on both chips about two inches from the board . Bottom side of the board only . Let it cool down . Installed without pads and backlights and tv worked ok . I put a protective plastic liner on the metal frame before installing for protective measures against it hitting the metal . Two days and still working . Hope this helps others with this problem . May be a bandaid on a problem but at least I know now the digital main was the problem . Plus I couldn't find any identical boards online so this will have to do for the meantime . Hope you guys haven't tossed out your TVs yet .

[triplefour]

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

wow. i am very motivated to dig this tv out of storage to check for what you saw. thanks!

[brandx34]

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

I am having same problem. I have changed all boards except for TCON board (its on order). Anything else I can try in the meantime?
New:
PSupply
Led driver board
Main board
Changed U202 on original Main board (Nothing so, I changed the board)

[d(-_-)b]

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

Same issues here, same symptoms.
Checked Q210 - Good
Checked D9202, D9204 & D9206 - Good, steady 24v.
Ribbon cable ok.
Replaced EEPROM twice, no difference.
Currently no one has my mainboard on stock (VIZIO P502UI-B1E XECB0TK004060X 715G6924-M01-000-005K TPT500DK-QS1 REV.SC1E). Vizio = POS

[ARGO]

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

I am having same problem. I have changed all boards except for TCON board (its on order). Anything else I can try in the meantime?
New:
PSupply
Led driver board
Main board
Changed U202 on original Main board (Nothing so, I changed the board)

Have you replaced t-con? Any changes?

[jneupauer@sbcglobal.net]

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

we had a dead set arrive.. no lower left stand by lamp or on off button function.

Opened up and power 12v and 24v was there.

I saw the post on the thermal pads under the board.
I removed the pads and cleaned the board with 91% alcohol.

The power switch function was restored.
turn on... the led stby lamp lights then fades out ... power supply stays on.

still no screen light up, I will order eprom which supposedly common a problem.

[ARGO]

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

My TVs is still sitting in the corner and waiting for solution...

[shafercomputers]

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

I'm a tv technician for a consumer electronic company and had a customer bring in this model with similar issues (No backlight/No picture). New Main board fixed it. Only place I could find it for a reasonable price was ebay. From manufacturer it was around $350 if I remember right.

[shafercomputers]

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

The part number(Partial)you have to go by on the P502UI-B1E Serial#LTY6RKBQ is XECB0TK0040 on the Main board. Here's the manufacturer link:

https://encompass.com/item/10730980/...XECB0TK004030/

[jneupauer@sbcglobal.net]

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

so.... the eprom that I ordered and installed did NOT fix it.

I scoped the ldvs cable... there was no signal on any pin.
Also no enable bl on pin 9 cn805

then I tried baking the board in my toaster oven .. 12 minute timer, 400 degrees.

the set worked.
PTS may referb the board at $125..... https://www.ptselectronicsinc.com/

[philtvman]

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

so.... the eprom that I ordered and installed did NOT fix it.

I scoped the ldvs cable... there was no signal on any pin.
Also no enable bl on pin 9 cn805

then I tried baking the board in my toaster oven .. 12 minute timer, 400 degrees.

the set worked.
PTS may referb the board at $125..... https://www.ptselectronicsinc.com/

Digging this old thread up. Had a unit with same symptoms...no picture, no backlights, power light slowly faded out...Replacing EEPROM didn't fix it. Before I picked up a board for $125 on eBay, I threw the old main into the oven at 400F for 12 minutes, let it cool for 30, and *poof* fired up just fine. No idea how long it'll last, but hey it's better than a dead set

[ARGO]

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

I bought cracked LG 50UH5530 for $20 and swapped the screen from Vizio to LG. They are the same...

[jdbird613]

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

I just tried putting main board in oven at 400 degrees for 12 min...let it cool, hooked it up...Vizio P502UI-B1E is working just as it should. Can anyone tell me what was fixed by putting board in the oven like that? That's def a new one for me! Awesome Though!

[TomRathbun]

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

I'll be dogged I just cooked my board in gas oven 400 degrees 12 minutes. Could not believe it when it turned on.