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Old 10-09-2019, 06:43 PM   #1
z0oinks
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Default Backlight and Sound But No Video on Vizio P502UI-B1E

Hey everyone.

Found this TV on the side of the road and the guy who put it there said one day it just stopped turning on.

I took it back and determined that I need to replace the power supply board. Did that and the TV turned on and I could hear audio from my source, but no video and no backlight.

I replaced the EEPROM but that didn't fix anything.

Found https://www.badcaps.net/forum/showpo...&postcount=136 and tried throwing it in the oven.
This fixed the backlight, but still got no picture.

After that, I tried replacing the T-Con board, but that didn't help either.

I've been looking and can't find a main board (XECB0TK004060X) for a decent price. Is there anything else I can try or am I out of luck on this one?
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Old 10-09-2019, 08:54 PM   #2
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Looked and I didn't see an edit button....

It's not possible to use a different model number main board is it? I see ones that look the same with slightly different model numbers all over eBay and they're very tempting
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Old 10-10-2019, 08:01 AM   #3
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Your Post Header says Backlight and sound but no video. Then inside the Post you say you hear audio from my source, but no video and no backlight. Are your Backlights working? If YES then your problem lies in a shorted capacitor on the Panel Bd. ( the long boards attached to the LCD Screen). If NO then the LED Driver in the PSU if at fault.
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Old 10-10-2019, 08:34 AM   #4
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Quote:
Originally Posted by z0oinks View Post
I've been looking and can't find a main board (XECB0TK004060X) for a decent price. Is there anything else I can try or am I out of luck on this one?
Have a look at shopjimmy's website and see if they suggest suitable replacement boards
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Old 10-10-2019, 09:56 AM   #5
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

So are you getting the backlights or not?
Please upload good clear pictures of the whole back side of the TV showing all the boards.
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Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
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TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Old 10-10-2019, 11:04 AM   #6
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Quote:
Originally Posted by Andrew F. Ali View Post
Your Post Header says Backlight and sound but no video. Then inside the Post you say you hear audio from my source, but no video and no backlight. Are your Backlights working? If YES then your problem lies in a shorted capacitor on the Panel Bd. ( the long boards attached to the LCD Screen). If NO then the LED Driver in the PSU if at fault.
Quote:
Found https://www.badcaps.net/forum/showpo...&postcount=136 and tried throwing it in the oven.
This fixed the backlight, but still got no picture.
Sorry, I was going step by step with what I did and what it fixed.
I didn't have backlight at first, but it came back after throwing it in the oven.
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Old 10-10-2019, 11:11 AM   #7
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Just went to go take the pictures and now the backlight isn't turning on again -.-

Pictures are here: https://photos.app.goo.gl/zek6Zbn4gaWfQWJN6
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Old 10-10-2019, 07:48 PM   #8
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Another update: Backlight is working again. Didn't change anything besides putting two screws in the main before putting it away for the time being
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Old 10-10-2019, 09:24 PM   #9
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Since now you do have baklights, so what do you see on the screen if you have the ribbon cables between the T-CON and the LCD panel connected one at a time?
BTW, make sure to put all the screws for the boards back in place.
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Old 10-10-2019, 10:42 PM   #10
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Quote:
Originally Posted by budm View Post
Since now you do have baklights, so what do you see on the screen if you have the ribbon cables between the T-CON and the LCD panel connected one at a time?
BTW, make sure to put all the screws for the boards back in place.

I don't know what's going on with the backlight. Sometimes it turns on, other times it doesn't. When it does turn on, it'll stay on indefinitely. But if I turn the TV off and back on, the backlight might not turn on again.

When it does work, this is all I see on the screen regardless of what's plugged into the TCON:
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Old 10-11-2019, 09:59 AM   #11
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

"When it does work, this is all I see on the screen regardless of what's plugged into the TCON:" What do you mean by " regardless of what's plugged into the TCON"????
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Old Yesterday, 08:45 PM   #12
z0oinks
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Default Re: Backlight and Sound But No Video on Vizio P502UI-B1E

Quote:
Originally Posted by budm View Post
Since now you do have baklights, so what do you see on the screen if you have the ribbon cables between the T-CON and the LCD panel connected one at a time?
Quote:
Originally Posted by budm View Post
"When it does work, this is all I see on the screen regardless of what's plugged into the TCON:" What do you mean by " regardless of what's plugged into the TCON"????
When leaving both disconnected, I see what is shown in the picture. When I have the left ribbon cable attached, I see the same thing. If I disconnect the left cable and attach the right, I see the same thing.
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