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

[d(-_-)b]

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

Hi. New member here, first post. Not meaning to revive an old thread but just wanted to add myself to the list of folks that had success with the main board oven baking trick.

I purchased the tv for next to nothing from someone that wanted to get rid of it. The symptoms included no backlights, picture or 24V anywhere on the power supply board. It did have 12V but not 24. The power light either came on and then faded after a few seconds or flashed 15 times and then repeated that after a minute or so, as if it was cycling. I removed the sticky pads from the bottom of the board and cleaned the gunk off as someone else did. After that I baked the board for 12 minutes at 400 deg. F. I let it cool for 30+ minutes and then reinstalled the board. VOILA the tv fired up and appeared to have all normal functions. 24V is now where it's supposed to be.

Of course the question now is how long the repair will last?? At the very least I now know which board was defective and can replace that when/if the problem reappears.

I want to thank those that posted their oven bake successes! I was very close to buying a power board thinking that was the culprit until I found this thread. The information saved me a lot of time and money. This forum has a lot of great information.

What I would like to know now is how long this repair is lasting for those that have done it.

1 month for 1st attempt @ 400F / 12 min
28 months for 2nd attempt @ 400F / 15 min
---still working after the 3rd attempt @ 400F / 18 min from a day ago.

[d(-_-)b]

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

Obviously I can't go that high (423F/218C) when using a kitchen oven. For now it's working fine but next time I think removing the chipsets and re-balling/re-soldering is the way to go.

[diif]

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

Lead free solder melts at at 218c or 423F.

[d(-_-)b]

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

Third reflow in 2.5 years. This time was 400F/202C for 18 min and it's working again.

@diif - true, a proper reflow should take way less but we're not talking about "proper" here.

Next time I might have to get the hot air station from the box and actually use it. Let's see how long will 3rd one last. Hopefully it's a charm.

[diif]

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

2 years 4 months later and I'm back to square 1: no image at all, just the light for the power goes on and off when pressing the power button.

Garbage in, garbage out. Vizio.

Next baking session will be more than 15 min or even the hot air station.

2 and a bit years for a relow is good, it's not a cake, it doesn't need more time, just a little more heat. A proper reflow is done in around 5 minutes and that includes cooling.

[nomoresonys]

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

https://www.youtube.com/watch?v=vAJ86eW8IQc

[d(-_-)b]

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

2 years 4 months later and I'm back to square 1: no image at all, just the light for the power goes on and off when pressing the power button.

Garbage in, garbage out. Vizio.

Next baking session will be more than 15 min or even the hot air station.

[frannyjunk]

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...

I tried heating the main board. 1st time the backlight came on, but did not get Vizio logo. Next time I must have fried it completely because no backlight anymore. So, I am interested in finding a cracked 50" tv and replace with the good panel. Will this p502ui-b1 panel work in most 50" UHD tv?

[RainStorm]

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

I also threw mine in the oven for 10 minutes at 400F I guess, my oven is really old.
Just put it on the rack with the heatsink side down. Downside is my coax port melted I think.. Its jammed now.

I removed the thermal pads before throwing it in the oven, and it worked great. Other than that I had to reseat a tcon cable I was fenaggling with and worked fine afterwards.

Second vizio tv I've had with bad solders.

[JeffN9]

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

Hi. New member here, first post. Not meaning to revive an old thread but just wanted to add myself to the list of folks that had success with the main board oven baking trick.

I purchased the tv for next to nothing from someone that wanted to get rid of it. The symptoms included no backlights, picture or 24V anywhere on the power supply board. It did have 12V but not 24. The power light either came on and then faded after a few seconds or flashed 15 times and then repeated that after a minute or so, as if it was cycling. I removed the sticky pads from the bottom of the board and cleaned the gunk off as someone else did. After that I baked the board for 12 minutes at 400 deg. F. I let it cool for 30+ minutes and then reinstalled the board. VOILA the tv fired up and appeared to have all normal functions. 24V is now where it's supposed to be.

Of course the question now is how long the repair will last?? At the very least I now know which board was defective and can replace that when/if the problem reappears.

I want to thank those that posted their oven bake successes! I was very close to buying a power board thinking that was the culprit until I found this thread. The information saved me a lot of time and money. This forum has a lot of great information.

What I would like to know now is how long this repair is lasting for those that have done it.

[d(-_-)b]

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

IT WORKED!!! THANK YOU ALL !!!

I cooked the Mainboard for 12 min @ 400 F and let it cool until next day (I actually forgot about it) and next day I decided to give it one more try before dumping the whole set in the dumpster since nothing worked in the past 4 months (EEPROMs, transistors...). Sure enough the tv is working just fine for 2 days now (roku and plex mostly) with no issues whatsoever.

I'll post back if/when (hopefully not, knock on wood) the tv goes bad again. Till then many thanks to those who posted this possible fix since my board it's not available anywhere.

Well...looks, like any miracle, it didn't last for too long. Slightly more than a month. Last night I baked the board again and it's working fine again. This time for 15 min and slightly lower in the oven.

Will see how much will last this time.

[d(-_-)b]

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

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

IT WORKED!!! THANK YOU ALL !!!

I cooked the Mainboard for 12 min @ 400 F and let it cool until next day (I actually forgot about it) and next day I decided to give it one more try before dumping the whole set in the dumpster since nothing worked in the past 4 months (EEPROMs, transistors...). Sure enough the tv is working just fine for 2 days now (roku and plex mostly) with no issues whatsoever.

I'll post back if/when (hopefully not, knock on wood) the tv goes bad again. Till then many thanks to those who posted this possible fix since my board it's not available anywhere.

[nomoresonys]

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

Ok, now to make the fix last as long as possible, cut a hole in the back cover of the tv, right where the bga is and install a fan so it can run as cool as possible.

[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.

[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!

[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...

[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

[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/

[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/

[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.