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-   -   Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio (http://www.badcaps.net/forum/showthread.php?t=31649)

pyr0ball 09-18-2013 08:20 PM

Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
OK so I've got a TV handed to me by a customer that I figured would be a cinch to fix based on previous experience with the symptoms. Turning into a real conundrum now tho.

Anyhoo here's the skinny:

Symptoms:
Screen powers on, momentarily shows the Sceptre logo, then fades out to black in about 500ms. Audio continues to function normally, and the TV is detected properly on a Windows laptop via HDMI.

Troubleshooting:
My initial thought was that the t-conn board must be losing voltage and crapping out, but testing with a multimeter I'm getting a rock solid 5vdc on all the pins I should be. Thinking it still might be the T-Conn board I ordered a replacement from ShopJimmy and got that installed today, but still no video. Just for giggles I decided to test out all the voltages across all of the connectors that were labelled, and they all come out just fine. Lastly I figured the video processing cpu must have an issue (i'd seen similar things come up with the Samsung 305T) so I gave that and the ram chip next to it a reflow. Still no dice. I found a few posts on here about a Sony Bravia TV using the same panel that had an issue with the ribbon tabs coming loose, so I dismantled the LCD panel and tried putting some pressure on the tabs while I was feeding it video from a PS3. Still no dice.

I'm all out of ideas. anyone got anything more I could try?

budm 09-18-2013 09:02 PM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
So the backlights are on but no pictures?

pyr0ball 09-18-2013 09:11 PM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
Correct, backlights on, audio still working, but black screen

pyr0ball 09-18-2013 10:35 PM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
I just started poking the voltage regulators after reading one of those posts in your sig. I think I found a bad regulator! theres two of the same model next to eachother, and a third on a different part of the board, and one has some different values. The last character on the second line looks like a backwards "L" which is strange.

1117 B
AD 221 |
0.56
1.80
3.23

~and the other two~

1117 B
AD 221 |
0.0
1.23
3.23

I cant seem to find any fixed LDO's with voltage at 1.23, so I'm guessing this is an adjustable? I've got a local shop that sells SMD components so I'm going to go check if they have one tomorrow and try replacing it

budm 09-19-2013 09:10 AM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
1117 B
AD 221 |
0.56
1.80
3.23
This is correct, 1.25Vref + 0.56V (Adj pin) = 1.81V output pin (middle pin), within 2%.

1117 B
AD 221 |
0.0
1.23
3.23

OK @1.23V within 2%

pyr0ball 09-19-2013 01:18 PM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
OK gotcha, I wasnt sure about that.

Any thoughts as to what else I can poke at? Or is it just a bad panel?

pyr0ball 09-20-2013 10:55 AM

Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio
 
Just poking this thread again, I'm all out of ideas


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