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T-CON Board IC Complaint And Backlight Issue Resolved In SONY BRAVIA KLV-32S400A

By on August 5, 2022
T-CON Board IC Complaint And Backlight Issue Resolved In SONY BRAVIA KLV-32S400A

lcd tv gamma problem repair

This LCD backlight TV was brought to me with the complaint that it had bizarre images when switched on, after leaving it in the attic for almost an year. Though I received the TV a few months back, I did not have the time to look into the problem due to various domestic problems. Finally, when I took it and switched on to see what was the trouble, error codes were blinking, indicating a backlight failure. I opened the TV and subjected it to a thorough cleaning of inside.

how to fix lcd tv with negative picture

When I checked the inverter, I noticed that the voltages for its proper function was ok. The circuit was using OZ964 IC. So, I checked the output transformers using Multimeter selecting ohms range; of-course after switching off and discharging the caps there. I could not find anything wrong in the secondary as all of them were reading almost same. Unfortunately I do not remember the value, but guess it might have been around 1.5K.

Looked for any defective components or value changed resistors and could not find any. On consultation with my techie friends, they were of opinion that because of ageing, the LCDs might be drawing a little more current, as a result of which the driver IC senses it and goes to protection mode. They suggested bypassing the protecting by connecting an LED from pin 4 to ground, which I did. Now When I switched on, the backlight was on and this is what I saw. I am also giving pictures of the Inverter IC and the bypass done.

gamma negative picture repair in lcd tv

inverter lcd tv board

testing inverter tv board with led

Focus turned to the T-con board to trace the reasons for the improper images. When I shared the snaps with my ever-ready-to -support techie friends, they told me that the problem could only be due to the following IC (AS-15), which is very common. I am also providing a picture of the T-Con board:

as15g gamma ic replacement

The datasheet of this IC can be downloaded from: https://www.datasheetbank.com/datasheet-download/140794/1/ETC/AS15-HG

I used my blower and removed the IC. You can take a look:

how to solder out as15g ic

As you can see, I applied solder all-around for easy removal of the IC. Then replaced the same with a bought out IC. My techie friends had warned me that the ICs available in the market might not function and I may have to remove and replace a few times, using different batches of the IC available from different sources. I ordered the IC to a few places.

Got about five of them. Tried replacing these one by one four times, but got different results, which varied but without solving the image problems. This was not done at a stretch, but on various days later. I really got fed up and kept aside the TV for some more weeks, as I had urgent domestic problems to take care of.

By this time I had established contacts with one of my friends who had opened a Panel repair, Bonding and replacement shop about 20Kms away from my home. I took the TV to him hoping to resolve this problem. I had already removed the last put IC. He checked the T-Con Board and asked me to give another new IC from a different batch. I gave the one picture of which is given below:

hot plate for as5hg ic

Firstly he cleaned up the area thoroughly and applied fresh solder in all places. Then used a hot plate (See picture above) which he kept underneath the board and allowed the applied solder to melt very well. Then kept the IC in proper position and switched off the heater. Took the T-Con board after it cooled off. Then retouched all the points once again and cleaned the board thoroughly. The entire work was so professional that the soldering looked like a factory finish. Amazing talents! The T-con Board was then reconnected, but with more or less the same results.



The first doubt that the IC soldering using the hot iron would not have been proper was cleared now. The problem was with the IC. So, he hunted for one from his stock, which looked like original and went through the process of removing and re-soldering the new one. Reconnected the board and switched on and both of us were relieved to see a good picture! Gave me a sigh of relief!

how to fix lcd tv with gamma ic problem

So, intense satisfaction found its way into the collection bag!

 

This article was prepared for you by Parasuraman Subramanian from India. He is 72 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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14 Comments

  1. Albert van Bemmelen

    August 5, 2022 at 10:17 pm

    A very odd repair that used a chip that came in various versions but is known for only working with one of them out of a batch of those? Very strange Sony Bravia TV!

    Likes(5)Dislikes(0)
    • Parasuraman S

      August 6, 2022 at 9:21 am

      Yes, strange are the ways of working of Sony sets! Many thanks for your comments!

      Likes(0)Dislikes(0)
  2. Waleed Rishmawi

    August 5, 2022 at 10:22 pm

    Good AS-15 are hard to find. Once I ordered 50 IC’s 10 of them were deceive. I still have some left in the shop but sad to say LCD TV’s are not being used like before in my home town.
    One way to find out if the Gamma IC faulty is by touching it while the tv is on and if over heating just replace and you should be fine. Thanks for sharing your experience with the group. Have a blessed day

    Likes(3)Dislikes(0)
    • Parasuraman S

      August 6, 2022 at 9:22 am

      Many thanks for your comments and tips! Yes, but touching an IC like this might damage it due to static discharge!

      Likes(0)Dislikes(0)
  3. Imoudu.O

    August 6, 2022 at 2:46 am

    Thanks for sharing this,it's an eye opener for me.I also have sony 32" LCD Bravia KDL-32EX401 on my bench. It's gone to protection mode with light blinking.
    I see the legs of red led light is solder to o resistor and c14 cap.Is it the anode that is solder to c14 which I guess is connected to pin 4
    of inverter ic?I intend to try this on the sony tv with me.I need more enlightening,pls help me out.

    Likes(2)Dislikes(0)
    • Parasuraman S

      August 6, 2022 at 9:23 am

      How many times, is it blinking? Six times indicate backlight problem. 1-4 or 5 times indicate power supply or mother board problems.

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

    August 6, 2022 at 6:24 pm

    Very hectic job, , I think proper matching of IC numbers is must & are programmed so in safer side copy the data from Bad IC & reprogram new IC. Both the ICs GAMMA & Dc to DC are programmable.

    Likes(2)Dislikes(0)
    • Parasuraman S

      August 7, 2022 at 11:14 am

      Many thanks for your comments and tips!

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

    August 6, 2022 at 6:31 pm

    Many time we feel Ordered IC is fake but unfortunately we never think other side about IC Programming Because some ICs are blank and some are programmed for Particular Model & Series.
    now in new coming technology every communication IC,Power IC, Processor ICs are programmed.

    Likes(2)Dislikes(0)
    • Parasuraman S

      August 7, 2022 at 11:15 am

      Very true! Many thanks for your tips!

      Likes(0)Dislikes(0)
  6. Lynn Blakely

    August 7, 2022 at 12:27 am

    to Parasuraman S & Yogesh Panchal It was good to find a good IC to do the repair on the Sony. copying the program from the defective IC probably wouldn't fix the problem by using that in the replacement IC. We have replaced Rom chips in VCRs with ones that were programed by the manufacturer to repair VCRs. What makes the program in the IC become defective? Touching
    an IC won't damage it if you first touch the ground or metal of the unit to discharge any static you may have.

    Likes(2)Dislikes(0)
    • Parasuraman S

      August 7, 2022 at 11:16 am

      Many thanks for your comments and tips!

      Likes(0)Dislikes(0)
  7. Michael Gallegos

    August 7, 2022 at 7:19 am

    Wow! I admire your persistence and you must appreciate the good and knowledgeable techie friends you can call on for help. Well done!

    Likes(2)Dislikes(0)
    • Parasuraman S

      August 7, 2022 at 11:17 am

      Yes, fortunately I have a number of techie friends and a group where problems discussed and solutions shared. Even what one did to solve a problem is also shared in detail as a guidance to all its members! Many thanks for your comments!

      Likes(0)Dislikes(0)

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