Repair of Philips LED Smart TV – 55PFT6100/98
I had received a Philips LED TV from a friend. It came with the problem of, no picture but with sound.
Before dismantling the TV to confirm the failure, I powered up the TV to see myself the actual fault. Indeed, there is picture and sound but picture was not visible due to no backlight. You have to look closely or shine a torchlight to see the picture in the display panel. This confirmed that the supply is going into the Mainboard, T-con and LED Panel. Next, I had confirmed whether the mainboard sent back blacklight ON signal to Power Supply Unit (PSU). For this I needed to dismantle the cover to find out.
Picture of back cover dismantled
Power Supply Board (PSU) connecting to the mainboard
Checking that the signal from the mainboard to the PSU at CN203 after switching on the TV at BL_ON. The signal or 4.3Vdc was present.
This test confirmed that the mainboard is working and the next step is to confirm whether there is output to the LED strips from the PSU.
There are 2 pairs (CN301) of LED strips – LED1+ and LED2+. The first (LED1+) was tested to have 130 Vdc and second (LED2+) was receiving 113 Vdc from the PSU.
These results indicated that one set of LED lights having higher voltage that the other implying that there could be a fault in the LED strips.The final test was to conclude which LED strip is causing the TV to have no backlight by using the backlight light tester (SFD300V).
After removing the connector going out from CN301 to the LED strip, using the backlight tester with TV power in OFF condition, the first set (LED1+) failed to start the LED but the second set (LED2+) started to light up slowly. This test confirmed that the first set LED1+ is causing the TV to have no backlight. Now to dismantle the LED TV glass panel from the chassis.
Removing the LED TV glass panel is difficult. One has to take precaution not to break the glass, once cracks appears, the TV will be unusable. Once the back chassis has been removed there were 12 strips of LED divided into 2 sets. LED’s connected to LED1+ had 2 LED’s not lighted up when using the LED backlight tester checking each strip at a time. Replacement strip took 1 week plus to arrive from AliExpress.
LED1+ after replacement was made
LED2+
TV back to life after assembled.
It was an experience to give life to this TV and begin the first time for me the satisfaction of completing the task was just great.
For this TV repair I had my son Shawn to assist and somehow this session got him hooked on and now he is keen on taking up electronic course where I attain my basic knowledge, it’s from our one and only, Jestine Yong, KL Malaysia. Thank You Jestine Yong.
Thank You
This article was prepared for you by Michael Selvam from Singapore, a 57 year old zealous electronic enthusiast. As a passionate electronic repair hobbyist, he tinkers with home entertainment systems and any faulty electronic equipment he gets his hands on. He obtained his knowledge to repair by reading books and took up the electronic courses I conducted. At present, he is employed as a Cluster Manager (Property Management) with CapitaLand and does his repair whenever time permits.
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Albert van Bemmelen
November 4, 2019 at 9:43 pm
A well done professional backlight repair! These repairs indeed are better done with help from others to move the heavy big panels safely. Nice to hear that you got your son interested in electronics after he helped fixing the TV! And welcome Michael to the club of enthusiast repair engineers on Jestine's Blog!
Michael
November 5, 2019 at 8:09 am
Thanks Albert!
Maher Diab
September 20, 2021 at 8:29 pm
Hello,
I have a T.V same model 6100s 55 inch, can you feed me the serial number for backlight strips, Please?
Robert Calk Jr.
November 6, 2019 at 4:38 am
Hi Albert. This time that I removed the panel on my 42" Sanyo, I used a pair of 4 5/8" diameter(close to 12CM) Tolsen dent puller suction cups that I bought from Shop Jimmy. They worked great and made the panel removal a lot easier!
Robert Calk Jr.
November 10, 2019 at 4:03 am
Sorry Albert, I made a mistake. My Sanyo is a 40", not 42".
Lawrence Otim
November 5, 2019 at 12:06 am
Nice Work Michael
and thanks for the article well ellaborated.
Michael
November 5, 2019 at 8:10 am
Thanks Lawrence!
Robert Calk Jr.
November 5, 2019 at 12:18 pm
Good job, Michael! My TV had a bad solder joint on one LED and a bad coupler connection between two LED strips.
Robert Calk Jr.
November 10, 2019 at 4:09 am
Sorry, Michael. After reading my old article again, there were 3 LED's that I reflowed, not just one.
The problem this time was another spring pin in a LED strip coupler connector. So I removed all of the LED strip coupler connectors and soldered all of the LED strip connections up with tinned copper wire. I am not going to tear this TV down again just because of a cheap LED strip coupler!
vasudevan
November 5, 2019 at 1:54 pm
nice article
Parasuraman S
November 5, 2019 at 4:27 pm
Excellent piece of intricate work done so professionally, that too by a hobbyist! Very glad to hear this! Many thanks for sharing your experience!
Tito Kanshulu
November 9, 2019 at 4:38 pm
Very good work boss. Backlight problem is an issue in led tv
Yogesh Panchal
November 9, 2019 at 11:46 pm
Michael,
Welcome! to Blog and thanks for sharing the article.
bachir
November 26, 2019 at 9:06 pm
good job sir i enjoy
Ivan
April 12, 2020 at 9:14 pm
thanks alot , this is awell detailed article , God bless you
Brandon Chua
April 29, 2020 at 7:24 pm
Awesome post... Learnt a bunch and love your passion for electronics!