Re: Help with Vizio P702ui-P3 Black Screen
The new main board arrived and has resolved the issue. All is working again. Wish I could have found the bad component, but suspecting it was one of the ICs and not something simple. Thanks again for all the help.
Russ-DS
Member
Last Activity: 06-19-2022, 10:54 PM
Joined: 12-09-2019
Location: Dripping Springs, TX
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Re: Help with Vizio P702ui-P3 Black Screen
No, I didn't try heating things up. The main board was getting plenty hot on its own while powered up.
I just bit the bullet and ordered a new main board off ebay with a return policy, so we'll see what happens on the ~29th.
Thanks again for all the help.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
I can't seem to find any issues with the cabling. I've been able to confirm that the left half has a perfectly good picture and has sound with a good source for about 1 minute, at which point it seems to do a partial reboot (based on the SPDIF light), followed by no power to TCON and no backlight until power is removed for a long time. While the left half is working the right half is static.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
I'll take another look at the cables, but didn't see any folds or pinches, etc. The picture on the right side during the <1 min before it shuts down (powers off TCON and backlight, the rest stays up) is actually like old school snow/static. I have not tried it with an actual source, and also do not use the speakers so have had them off. I can try that hopefully tonight.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
I can't seem to find any issues after some additional probing around. No visible issues under the heat sink either. The set continues to be able to be powered on for < 1 minute after having been off for a while before it shuts off the panel, with the left side working normally. I've attached a better picture of that.
I'm thinking I should just pull the trigger on a new main board, as I'm running out of ideas....Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
Good question, ideally I would like to repair the issue rather than replace the board, but am starting to suspect that may not be possible or as easy as I'd hoped. I'll go follow some of those voltages and check and re-seat the cables again and see if I an find anything.
Thanks again for the help.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
I've had no luck getting screen flash with Tcon cables disconnected, however I continue to be able to get it to power on with backlight for <1 minute after being off for an extended period of time. It then shuts off TCON ON/TCON 12v and the backlight.
When on, the left half of the screen seems to be working fine, while the right half is full static (see attached (very poor) photo)....Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
I disconnected each of the 4 ribbon cables one at a time powering on in between each, but did not see anything on the screen in any case. Not sure what I would have expected though with no TCON 12V power due to TCON ON low, and with no backlight.
Before doing this I did power on again after having been off for a day, and did get the backlight on for 30 seconds or so again, with just a gray screen, but could again not get that to repeat.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
Thanks budwich, I'll try that. I believe there are 4 cables. Please let me know what I should expect to see in the case of a good or bad panel.Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
So, disconnecting TCON ON from the main board and powering it externally did cause 12V on the TCON 12V pins on both connectors, but did not cause anything else to work. This makes me think the supply board is ok.
Separately, before I did that experiment, after putting back all the boards and reconnecting them after having been powered off for a couple of days, when I first turned the power on the backlight and I believe also the LCD did turn on. It only lasted for about 30 seconds, then turned back off. I was not ever able...Leave a comment:
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Re: Help with Vizio P702ui-b3 Black Screen
CapLeaker, yes, sorry, you're correct about the model number. Seems I can't edit the subject of the original post though.Leave a comment:
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Re: Help with Vizio P702ui-b3 Black Screen
Is "disconnect of the tcon to panel cable test" the test I described above (try to disconnect the TCON ON from the main board and power it through resistor), or something different? If something different could you please share a description or a link?
Thanks,
RussLeave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
Yes, pin 15 on the main board connector is TCON ON. With everything disconnected I measure 10K to gnd. I think that's probably the first of the resistors you found.
I'm not sure the best way to power it (TCON ON) with everything else on without cutting the wire. I'll try to see if I can pull it out of the connector. If I can figure this out should I expect the panel to come on?
I've attached the front and back pictures of the 4 boards.
Thanks again for all the help.
Russ...Leave a comment:
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Re: Help with Vizio P702ui-P3 Black Screen
CapLeaker, thanks for the reply. I only have the front of the main board and part of the power board. I'll have to get the others tonight or tomorrow.
I have looked closely at the front and back of the power board and the front of the main board and don't see any blown caps or other physical damage to components (I had been expecting to see something).
FYI, the TV has been working fine for 5 years. My son was watching it last week when he said the left half went black and the right half went static/pink....Leave a comment:
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Help with Vizio P702ui-P3 Black Screen
Hello, I'm hoping for some help debugging what broke on my Vizio P702ui-P3. I had originally thought it was an issue with the power supply board, but based on these 2 threads am starting to think main board instead:
[url]https://www.badcaps.net/forum/showthread.php?t=51443[/url]
[url]https://www.badcaps.net/forum/showthread.php?t=80351[/url]
My case is different than either of these. Here's a summary of what I've found so far:
- ~160V on main caps as expected with power off.
- Set's power LED lights when powered on, then I see the following... -
Re: New Members - please post your introductions here
Hello, Russ here. Looking for some help with my Vizio p702ui-b3.Leave a comment:
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