Singer 32″ Skyworth LED TV With Dim Display Repair
The complaint of this Singer Skyworth 32″ LED TV was no display but when I used a torch light to shine at the screen I could see dim display picture. This means the actual fault was dim display and not no display.
The cause of this problem was the LED backlight circuit not functioning-see the photo below:
As usual, in order to repair any electronic equipment one has to open up the cover. In this LED TV, it was easy to remove the screws and the cover can be lifted out easily. Once the cover was removed, I could see the mainboard and the power supply/ LED driver board. The LED controller board was located at the top part (long horizontal circuit board).
The first thing I do was to check on the output voltage to the LED backlights.
From the board marking of the LED backlight connector, it stated 60 vdc which means 60 dc volt is required to light up the LED backlight. However, from the measurement I’ve got only 26.6 volt which is abnormal.
So, I proceeded to trace the 60 volts line from the back of the connector and the line brought me to a circuit that has two big SMD diodes-see the photo below:
I took out both diodes to check (checking diodes off board is much accurate than to check it on board) and found one was shorted and the other one good-see the two photos below:
Since I do not have this kind of diode, I used a axial lead fast recovery diode with 3 ampere as replacement. I had to cut away the long lead and slowly position the diode onto the original location
After the installation of the diode, I powered On the LED TV and as expected, I’ve got 62.7 volt at the LED backlight connector.
The below two pictures is what I saw when everything were put back. Another job done and made some profits from this repair. If you wish to learn how to repair LED TV you can check out Kent’s and Damon’s ebook.
This article was prepared for you by Suranga Bandara who owns an Electronics shop in Anuradapura, Sri Lanka.
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Note: You may check out his previous repair article in the below link:
https://www.jestineyong.com/lg-slim-tv-with-one-horizontal-line-solved/
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24 Comments
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Yogesh Panchal
November 16, 2015 at 4:24 pm
Good Job! Suranga and thanks for sharing.
Thissera
July 24, 2018 at 10:37 pm
Thanks Suranga
Parasuraman S
November 16, 2015 at 5:27 pm
Good job! Your ability to get to the root cause of the problem is laudable! Please keep sharing your valuable experiences! All the best!
Gerald Millward
November 16, 2015 at 6:53 pm
I only repair computers, but inverter failure is also a common fault in computer displays, with this type of diagnosis and repair for desktop monitors, but usually just a case of replacing the small inverter unit in laptops. Innovative use of a standard diode here Suranga! SMD diodes of this type are common in laptop motherboards - but rarely of such high voltage - pity!
Suranga Electronics
November 17, 2015 at 3:46 pm
Thanks.. Mr,
Mahfoud
October 6, 2017 at 7:06 am
Thank u very much Mister u helped me here in morocco so i can repair.my tv cheeply
Albert van Bemmelen
November 16, 2015 at 7:41 pm
Nice repair Mr.Suranga. I tried to read the SMD code from the Diodes
on the Photos you took, but that was not possible. Since you didn't
mention this. But I understand that they both were connected in
parallel. So the max current to the Backlight Leds would be tops
about 6 Amps?
Robert Calk
November 16, 2015 at 7:49 pm
Good job, Suranga! I love reading articles where you do some good improvising to get the job done. It also saves your customer some
money!
Suranga Electronics
November 17, 2015 at 3:54 pm
Thanks Mr, I Like ur comm.
jose walter tenorio
November 16, 2015 at 10:18 pm
Good morning, good explanation , keep sharing , keep the peace of God .
beh
November 17, 2015 at 1:59 am
Thanks for sharing and keep it up SURANGA.
H
November 18, 2015 at 1:40 am
Great repair Suranga. I've substituted SMD Diodes for normal Diodes (with the same features or similars)sometimes. Keep up
Hicham
November 18, 2015 at 7:03 pm
Thanks Mr SURANGA for this sharing, keep it up.
joseph
November 19, 2015 at 1:32 am
Great one.
Mark Tembo
November 19, 2015 at 10:39 pm
Good initiative!
Claude
July 28, 2016 at 11:28 am
Great !!! very good illustration. Well understood and clearly explained.
Keep it Up. Proud of you
Rafael
November 20, 2016 at 12:03 am
thanks for sharing.
SHANMUGAM THANAPAL
March 30, 2017 at 11:10 pm
Really good thing sir. Good job posted by you, which will be very useful to beginners in led/lcd segment like me.
Mubashir
April 11, 2017 at 6:30 pm
Dear Suranga,
Good Job. I need help regarding UPS. I have Homage Matrix 1000 which is dead. I got it from neighbor. I want to repair it. I am trying to search on net the schematic diagram of it. I worked but fail to repair it. There is supply missing on pwm controller pin 7. I read the book of Mr. Jesting but something I am missing on it. some parts are already missing on it. I thing without schematic I can't repair it. Please help me.
rab
August 17, 2017 at 4:23 pm
thanks you
Prasantha Thissera
July 24, 2018 at 10:41 pm
Thank's suranga
Mulenga M
March 29, 2019 at 5:03 am
It worked! Excellent piece. Thanks alot
Woozie
May 8, 2020 at 9:50 am
I have the same problem. No backlight, good audio and flashlight give faint image. My LED connector gives only 12v. But in my TV There is only one board which is main board as well as mother board. There is no separate board for them. And how can I repairs instead of replacing.
Acabala dominic
September 19, 2021 at 2:34 pm
Indeed you're the best teacher