Sony TV standby LED blinking 6 times solved

By on December 17, 2016



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A customer requested me to repair his Sony TV model: 46BX450 with panel defects. He commented that somebody had quoted him the price of a new panel is so expensive that it is not worthwhile to change it.

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When I turned on the set I observed that the standby LED blink  six times  with the Sony Logo appeared briefly on the screen before it shut down indicating that the backlight was working. According to the Sony service manual the fault lies with the panel assembly and recommended to change it.. The term “panel assembly” on the service manual include the backlight inverter board, CCFL lamps and the LCD screen.




Since the inverter backlight board is easily accessible , so I proceed to check it first. On analyzing the inverter board I notice the connector pin 11 (ERR_OUT) of CN101 has an error feedback voltage to the main board (photo 1). Photo 2 showed the measured error voltage  of 3.6v which is high and it is supposed to be near zero volt

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The 3.6V feedback error voltage confirmed that either or both the inverter board and  front LCD panel were faulty. The main board protection mode will be activated and will shut down the TV upon receiving this error voltage ERR_OUT. On the inverter backlight board there are 3 high voltage transformers (part no:34018AD) which are prone to failure i.e T100,T200 and T300 (Photo 3). Testing these high voltage transformers are complicated but the inductance measurement will be able to tell whether it is faulty. Since the 3 transformers are identical with the same part no. , we can compare the differences in the inductance measurement.

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Part no: SSI460_12F01

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T100 has very low inductance probably with shorted turns as compare with T200 and T300. The protection circuit of the inverter must have sense the abnormal drives to the defective transformer or unbalance load on the CCFL lamps and caused it to generate an error voltage to trigger the main board  to shutdown. I wanted to change the inverter backlight board or  transformer but unfortunately either part is out of stock in the market.

Finally, I found a supplier in China who can offer me an alternative board which can work with this model. Physically it does not looks compatible with the original Sony but the supplier insist that it can work. The price is attractively low so I give it a try. Photo 4 show the replacement board from China with magnetic feet for the screw holes since it dimensionally different and with plug-in pcbs & wires to the appropriate high voltage brackets of the CCFL lamps.

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I would expect the TV to work after replacing the backlight inverter board but  disappointed that the fault remain as before. I suspect there are more than one faults responsible for the shutdown.

Next, I removed the front LCD panel screen to check on the CCFL lamps. Since I do not have CCFL tester to verify each individual lamp working characteristic, I have to rely on common sense and visual judgement. Some of the lamps have excessively large area of black ring on one end, I guessed these were faulty or leakage lamps (Photo 5).

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I changed a few of the CCFL lamps which are with excessive dark ring. The panel were re-assembled back and power on with China backlight inverter board. I make the correct judgment, the video was able to turn on now and the shutdown does not reoccurred. The error voltage ERR_OUT measured  is 0.036V with the China backlight inverter board as shown in Photo 6

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I want to re-confirm the original  backlight  inverter board which I suspect was faulty, so I replaced the China board with the original Sony backlight  inverter board. When  power was turned on, the shutdown fault re-occurred. Now I can confidently conclude that the original sony  inverter backlight board and those CCFL lamps with excessive large black rings were defective.

In my personal opinion, a better solution will be to change the high voltage transformer rather than changing to another version of the backlight inverter board. In this case I have no other option unless I am able to salvage the require part from another defective TV. I have also tried interchanging T100 and T300, by chance I was able to switch on the TV without shutdown fault. The error voltage measured on the Sony backlight inverter board is 0.04V only (Photo 7). The only problem was the backlight was not evenly lighted up and  a faint dark horizontal band  can be seen on the screen with high contrast video.

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The customer was very happy to see the TV working again and the repair cost is very much cheaper than the price of a new panel.

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I hope this article will be useful for those who encounter similar problems with Sony LCD TV. It may not be the best solution but it provide an alternative solution rather than throwing it into the waste dump .

skwong

This article was prepared for you by SK Wong from Malaysia and he graduated from London with a degree in Electronics and Electrical Engineering. He has more than 40 years of experience in the consumer product manufacturing. With the passion to repair electronic products from young , he has been doing it part time until now.

Currently, he can provide turnkey solutions for consumer products including services from idea or concept to design , prototyping , finished products (including electronic,mechanical and plastic parts) and manufacturing.




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Note: You can check his previous repair articles below:

http://jestineyong.com/sharp-lcd-tv-no-power/

 

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27 Comments

  1. Bholanath Adhikary

    December 17, 2016 at 5:46 pm

    Very good job.

    Likes(1)Dislikes(0)
  2. PARASURAMAN

    December 17, 2016 at 6:25 pm

    Excellent professional solution! Exposes your indepth knowledge of the circuit and functions!

    Likes(1)Dislikes(0)
  3. Bulent NUR

    December 17, 2016 at 6:37 pm

    Very full informative thanks very much for sharing.

    Likes(0)Dislikes(0)
  4. josé walter tenório

    December 17, 2016 at 7:43 pm

    Obliged to share their knowledge in the analysis of the defect, very good, stay with the peace of God.

    Likes(0)Dislikes(0)
  5. Mohamed Sittiq M

    December 17, 2016 at 8:37 pm

    Dear Sir,

    super explanation.

    Thanks
    Mohamed Sittiq M
    India

    Likes(1)Dislikes(0)
  6. Robert Calk

    December 17, 2016 at 9:07 pm

    Good job, Mr. Wong. It's always good to save money and save devices from the garbage.

    Likes(0)Dislikes(1)
  7. angelo

    December 17, 2016 at 9:52 pm

    Good job sir
    Keep it up

    Likes(0)Dislikes(0)
  8. Albert van Bemmelen

    December 17, 2016 at 10:34 pm

    Very interesting repair SK.Wong! Sony TVs are known for a couple of strange faults that only they seem to produce.
    A friend of mine had bought a Sony TV that had suddenly vertical stripes in the same week he just had it. And according to complaints from customers on Forums apparently many screens produce white areas or other strange faults after people had bought it.
    A also learned something from your article I had not heard of yet : Magnetic Feet. Where can you buy them and how can they be attached on a pcb?

    Likes(0)Dislikes(0)
    • skwong

      December 18, 2016 at 12:08 pm

      This is the first time I come across magnetic feet as well and it comes along with the board, Very innovative idea from the the supplier and very convenient for the end user without need to worry on the mounting problems due to screw holes not matching. You can find similar type of magnetic feet from Aliexpress website:
      https://www.aliexpress.com/item/M3-magnetic-feet-LED-display-Magnet-screw-Outside-thread-M3-magnetic-column-Cylinder-for-indoor-semi/32547129257.html?

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  9. Samsudeen

    December 17, 2016 at 11:53 pm

    Realy fantastic sir thank you verymuch,this is uselful to every technicians

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  10. mahmoud_tajpour

    December 18, 2016 at 1:31 am

    Hi dear WONG it was very interesting repair that you do well done.

    Likes(0)Dislikes(0)
  11. Anthony

    December 18, 2016 at 3:41 am

    Excellent repair and detective work to narrow down the faulty components S K Wong ! Thanks for sharing this article here so that I and others can benefit from your experience!
    Regards

    Likes(0)Dislikes(0)
  12. Lad

    December 18, 2016 at 4:47 am

    Congratulations on your good work!
    How did you know that T100,T200 and T300 could be those culprits instead of trying to repair the inverter backlight board from the very beginning?
    Thank you for your reply

    Likes(0)Dislikes(0)
    • skwong

      December 18, 2016 at 12:26 pm

      These high voltage transformers are prone to failure. There are numerous comments regarding faulty high voltage transformers from the forum.I just make a guess that the transformer could be faulty and it is not that difficult to check.By swapping the transformer positions around, if the error detection voltage changes then it is likely that one or more of the transformers are faulty.

      Likes(2)Dislikes(0)
  13. Sanjeet Veen

    December 18, 2016 at 1:19 pm

    Congrats for your work! helps us to learn the electronics so it is easy to do small job at home or even help to get rid from LED TV problems in the home if we learn the electronic industry concepts.

    Likes(0)Dislikes(0)
  14. zondiwe longwe

    December 18, 2016 at 5:52 pm

    I thank you very much for this article. Am having the same problem with my 32 inch Sony television.

    Likes(0)Dislikes(0)
  15. Yogesh Panchal

    December 19, 2016 at 12:02 am

    Sir,
    Thanks for sharing your experience and detail explanation.

    Likes(0)Dislikes(0)
  16. zaheedi farjan

    December 20, 2016 at 12:31 am

    Thanks a lot Jestine am learning a lot with you despite my 25 yrs in electronics hats off to u Jestine my regards to Wong too
    Zaheedi farjan with respect

    Likes(0)Dislikes(0)
    • Jestine Yong

      December 20, 2016 at 10:35 am

      Hi Zaheedi,

      You are welcome. Also need to thanks to all those who had contributed their repair articles that had made this blog a favorite place to read about electronics repair.

      Jestine

      Likes(4)Dislikes(0)
  17. Ruben

    December 20, 2016 at 2:56 am

    HI, YOU GOT A SMART MIND ,GOOD ANALYZER, VERY EASY TO JUMP INTO CONCLUSION , THANKS FOR SHARING W/ GOOD EXPLANATION . YOURS TRULY, RUBEN

    Likes(0)Dislikes(0)
  18. Chaminda

    December 22, 2016 at 7:24 pm

    Thanks for sharing on your experience.Good job sir.

    Likes(0)Dislikes(0)
  19. mohammed

    December 23, 2016 at 3:09 pm

    A very good article, but we in are suffering from lack of part.

    Likes(0)Dislikes(0)
  20. Hafidh Mahmood

    December 24, 2016 at 1:44 pm

    Thanx for sharing.

    Likes(0)Dislikes(0)
  21. Monday Kalimbanya

    January 3, 2017 at 5:07 am

    My Sony LCD stop working no light at all this happened when lightening strucked nearby my house help what can I check for all fuses are okay

    Likes(0)Dislikes(0)
  22. Humberto

    January 14, 2017 at 12:25 am

    Mr Wong, you have done a marvellous repair.

    Likes(0)Dislikes(0)
  23. Ulises Aguilar Pazzani

    January 15, 2017 at 10:37 am

    Mr Wong , very nice repair done great job SIR

    Likes(1)Dislikes(0)
  24. Dilum

    January 22, 2017 at 10:33 am

    I saw your voltage meter on one of your photo. I have same type one but
    my display is damaged. I'm finding a display for it. my meter is "FLUKE-8010A Digital Multimeter". If refer this as help I'm greatly appreciate.
    Thanks.

    Likes(0)Dislikes(0)

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