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Old 09-18-2013, 08:20 PM   #1
pyr0ball
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Default 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?

Last edited by pyr0ball; 09-18-2013 at 08:25 PM..
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Old 09-18-2013, 09:02 PM   #2
budm
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Default Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio

So the backlights are on but no pictures?
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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
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Old 09-18-2013, 09:11 PM   #3
pyr0ball
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Default Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio

Correct, backlights on, audio still working, but black screen
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Old 09-18-2013, 10:35 PM   #4
pyr0ball
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Default 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

Last edited by pyr0ball; 09-18-2013 at 11:26 PM..
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Old 09-19-2013, 09:10 AM   #5
budm
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Default 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%
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Old 09-19-2013, 01:18 PM   #6
pyr0ball
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Default 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?
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Old 09-20-2013, 10:55 AM   #7
pyr0ball
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Default Re: Sceptre X322BV-HD8AB02 / LTA320AB02 - No Video, Has Audio

Just poking this thread again, I'm all out of ideas
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