No Display In Sony LED TV Repaired (Solved By Masking Pins)
Make and model No: SONY, KDL-43W800C
Complaint reported : No display, but sound is ok
Observation : Complaint is genuine.
Action taken: Opened set after removing several screws, taking pictures of each area to put back the same type of screws. Removed cover, cleaned inside.
Trouble shooting done: No bulgy capacitors, burnt or strained components found. Checked and ensured that the power supply from the board is ok. Fed a video/audio signal and switched on the TV. Checked for voltages of VGH: 30.36, VGL: -10.51V, VCOM: 6.31, AVDD: 15.62, VDD: 3.3v and found these to be normal. Since the VGL was dropping to -6 and recovering to -10.51, suspected a problem in T-con board or Panel. Removed one side of the T-con cable that goes to the panel. Observed that the video was coming on to one side. Inserted it back and removed the other side.
Video was missing. Looked for the data pins near that cable, found it to be from pin 9 onwards, first 8 pins being the gamma input. Blanked four pins from pin 9 with a cut piece of paper, inserted the cable and switched on. Video was coming with vertical lines. So, blanked two more. Still picture was not ok. So, blanked the next two too. Now picture was ok. But there were a couple of not-so-prominent horizontal lines, which cannot be easily observed. (Guidance and instructions were from my technician friends through Whatsapp group) (Sorry, since I was talking to my guides and doing the paper piece insertion, I could not take pictures of it)
Post-service observation: Ran the TV in that condition for more than two hours and found it to be working well.
Final action taken: Closed the TV, putting back the screws in the appropriate places, studying the pictures taken and let the TV run for many hours before moving it to the delivery area.
Points to be pondered and discussed: While I carried out the guidance given by my friends, I am not sure how this masking is helping resolve such problems, though I know that many technicians are doing this.
My version is, if such short cuts are possible, why should the manufacturers, who are always keen in making an extra penny whenever and wherever possible, provide these circuits? A lay man cannot see a difference in picture quality with these track cuts! These are the points open for discussion and comments by our eminent readers; perhaps some technical explanation from our Experts across the Globe!
Result: Another satisfaction gem rolled into the bag, making sufficient room for itself!
PICTURE OF TV WITH ALL ITS BOARDS
THE T-CON BOARD, WITH STAGES OF REMOVING ONE SIDE
THE PROOF OF SUCCESS
This article was prepared for you by Parasuraman Subramanian from India. He is 69 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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https://jestineyong.com/no-power-in-pigeon-dvd-player-solved-and-defective-eye-unit-replaced/
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11 Comments
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Tayo
October 7, 2019 at 8:28 pm
Thank you for this article but i am a bit confused. Is Parasuraman saying that he used a piece of paper on the back of the flex cable to promote continuity of the contacts OR did he put paper over certain pins on the flex cable to PREVENT contact??? I cant think of a reason why this would work and give you good/usable image. I really need help wrapping my head around this one...
Parasuraman S
October 7, 2019 at 10:52 pm
Yes, masked the pins (as mentioned in the heading);i.e. in a way cut the data path!
Laron Locklear
October 7, 2019 at 11:19 pm
I have the same question in reference to blanked pins with paper
Axl Law
October 8, 2019 at 3:38 am
To prevent contact
Albert van Bemmelen
October 7, 2019 at 9:36 pm
Your level of repair on measuring and checking the VGH,VGL,VCOM,AVDD voltages and masking certain T-CON connector pins, is incredible and something I never heard about! As soon as you start publishing your own e-book with the knowledge you have about servicing and repairing CRT- and modern LCD CTV's I better buy it to keep up! This article was just to fast and short for me. It raises more questions I never new existed.
Parasuraman S
October 7, 2019 at 10:55 pm
These are some basic things any technicians do here. There are guys who by-pass the scaler board of the panel and even replace or by-pass the mosfets on the panel!
Robert Calk Jr.
October 9, 2019 at 10:19 am
Good job, Parasuraman! I read about that technique somewhere but I can't remember where I read about it right now.
Henry
October 11, 2019 at 2:36 pm
I have heard about this unorthodox method as well, it seems rather strange but at the same time it also appears to be working.
However, I do not understand the reasoning for it and still waiting for somebody to shine more light on it.
My question to Parasuraman, though. In the article above you mentioned checking various voltage levels on T-con board (VGH, VGL, AVDD, VDD, etc.) and founding them "to be normal". How do you know what the normal voltage level should be expected on those test points? Did you have a service manual for that TV model or are these voltages are common and typical for all T-cons?
Parasuraman S
October 11, 2019 at 10:04 pm
As mentioned by me in the article, I consulted my expert techie friends, who confirmed that the voltages are OK for the model. These guys have the practice of recording various voltages and several of them have even circuit diagrams and schematics of T-con Boards, mother boards and panels. Though they share these details, I have not asked for the schematics as it's embarrassing!
kingsley
October 16, 2019 at 12:06 pm
please i want to know more about how to repair decoders if you have the Technics
nader bahrami
December 9, 2019 at 4:08 am
Dear friend
mr.parasuraman
Special thanks to Sony for bringing this flaw to TV
Explain which data is interrupted and why it is not difficult to interrupt it. Thank you
nader