Sony Bravia LCD TV Repair

Discussion in 'Technical Repair' started by hamadahmad, Sep 11, 2013.

  1. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    Please guide me to troubleshoot my TV Problem
    Sony LED TV
    KDL-46EX520
    No Picture, but the Sound is OK.
    TV Channels are working without picture.
    Backlight appears when the TV is Plugged-In
    Fuse on T-Con is tested and is OK

    Regards.
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,003
    745
    The pcb on the left side is the Backlight inverter board, the pcb on the right is the video/audio processor, start there.
     
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  3. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    Is the set being fed a viable signal... hook up a DVR or other device and get back...
     
  4. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    Cordial Thanks Dodgydave for your Reply.

    Please tell me how can I identify that which board is creating problem i.e.
    Backlight Inverter Board, the Video/Audio processor or the T-Con

    The Audio is OK . TV Channels are there but there is no Video. Remote is working. Channels can be changed. No indication from Green or Red Lights. Both are stable.

    Please advise me Sir.
     
  5. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
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    Dear PackratKing, I did try all the options.

    I even attached my Laptop as well as my Sony Digital Camera with the TV. They previously worked.

    But now there is no response.

    Please guide me Sir.

    Also note that I'm by profession a Civil Engineer having a reasonably good knowledge of Electronics.
     
  6. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    Dear I read your profile PackratKing.

    You will definitely be pleased to know that I too love electronics. Do experiments, make electronic circuits, devices, circuit boards (PCBs) as well as other mechanical hobby repairs and experiments.
     
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Turn on the TV.
    wait a couple of minutes while observing the stby LED.
    Does it blink ?
    If it does, count them.
     
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  8. sheldons

    Well-Known Member

    Oct 26, 2011
    616
    101
    tcon pcb is not at fault-how many times does the standby led flash?what do you get when you press the home key on the remote control?if you get the menu display its localised the fault to a specific board which depending on the fault may scrap the set-if you have no display then it may well be scrap anyway-you need to check voltages on the psu B board(pin1 CN6001-5v for 22"/26" model,12v for the ex model/)
    if that supply is there its down to the G board-but check the wiring harnesses first going board to board -also check the logic level of the BL_ON line-at pin 6 of CN6002-if its lo replace the harness from B to G board-if its hi replace the lvds cable connecting the tcon pcb-if you still have no fault found and no display ill talk you thro the rest of the fault finding procedure
    depending wether you have deep pockets the next few steps involve detailed examination of the G board or replacement or scrapping the set......I have repaired a few of these sets and unless its done correctly servicing wise you will be going round in circles wasting time if you dont test things in the correct order......
     
    Last edited: Sep 12, 2013
  9. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
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    0
    Q: how many times does the standby led flash

    A: Stand By Light is stable, no blinking
     
  10. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    Nothing appears on the Screen when I press "Home" on the Remote Control.
    But the sound comes that the command has been executed.
    TV channels are OK and their sound is clear.
     
  11. sheldons

    Well-Known Member

    Oct 26, 2011
    616
    101
    have you checked all cables are firmly seated in the connectors from B board to G board and is that supply present on B board,pin 1 CN6001.....either 12v or 5v .....and what is the BL_ON line? The logic level here determines where we go next......
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Question is, does the backlite comes on?

    U can make sure of this from the back of the set. There are holes located all over the back plate. U can see if the back lite comes on or not.
    Confirm this.
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Another way to check the LCD is shine a bright torch from the sides.
    If the picture is there, u will see movement of the picture when u look closely and carefully while shining the light from the sides close to screen
     
  14. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    Dear sheldons:

    I've checked the voltage at Pin 1 of CN 6001 and it is 12.35 v

    Now please tell me what voltage should I check at other Pins of CN 6001 & 6002

    Regards
     
    Last edited: Sep 17, 2013
  15. sheldons

    Well-Known Member

    Oct 26, 2011
    616
    101
    if that supply is there and stable not pulsing its down to the G board-but check the wiring harnesses first going board to board -also check the logic level of the BL_ON line-at pin 6 of CN6002-if its lo replace the harness from B to G board-if its hi replace the lvds cable connecting the tcon pcb-if you still have no fault found and no display ill talk you thro the rest of the fault finding procedure....
     
  16. hamadahmad

    Thread Starter New Member

    Aug 2, 2010
    8
    0
    In the start of the problem, the video came for few seconds and then gone.

    I replaced the capacitors as shown. But no effect (No video but only sound).

    I also tested and replaced the FETs (KF 5N50).

    There is dim blue light on the screen. Sound OK Channels are Tuned, But No Video
    2. CN 6001 & 6002 Voltage Check.png

    Invertor Board (Back).jpg

    Invertor Board (Front).jpg
    Regards.
     
  17. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    There is a hijacking moved it to here.
     
  18. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Problem could be a bad LED in the backlit strip
     
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