No Picture and Sound In LED TV Repaired
This Abans 24″ LED TV came in with the complaint of intermittent no sound and no pictures but the front power LED light was good. Usually when you see that the front LED light was blue in color, you will assume the power supply was good and the main suspect would be in the mainboard with a corrupted data in the memory ICs or other causes.
This means when you heard from the customer that told you the problem was no picture and no sound (with normal power light), we normally did not suspect the power supply fault.
Sometimes our guess could be wrong because the actual cause was indeed in the power supply section. If you look at the photo below you could see two electrolytic capacitor were bulged and these capacitors were located in the 12 volt and 5 volt DC output line.
By right if there is any abnormal DC voltage in the 5 volt line, the front LED color would have been always red and not blue but somehow in this case the power led light remained blue and this is why you and I will never suspect it was the power supply fault!
With the replacement of two new capacitors, the display and sound were immediately got back to normal.
You can see the blue screen and good picture in the below photos. Before that the display was totally dark and no sound.
So, what you have learned from this article? Don’t quick to judge or assume that the power supply is good. You need to test all the output dc voltages first in the power supply before you can conclude that it was good. After that, then only you hunt for bad components in the mainboard, T-con board and etc. All the best to you!
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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https://jestineyong.com/wl-15-volt-zener-diode-multi-dc-output-adapter-faulty/
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Albert van Bemmelen
July 12, 2019 at 6:30 pm
Quick and pro repair in which normally the state of a working front led could easily have deceived us.
George Greenfield
July 12, 2019 at 7:11 pm
Greetings,
Experience has taught me to always inspect the Power Supplies outputs at the beginning of the troubleshooting process.
Many times I have found issues with the voltages and correcting those deficiencies put the item back in a working condition.
Good find on the "swollen" electrolytics.
George
Thomas
July 12, 2019 at 8:38 pm
Nice job! Unfortunately, as I see the build quality of this TV brand is bad. From my personal experience, I would choose Samsung or LG TV's because they are better quality.
Waleed Rishmawi
July 13, 2019 at 3:23 pm
Thomas: I agree on the Samsung TV quality but on LG sorry to say not any more. The LG product is Ok while they are up and running but when they need repair, the parts are hard to find and too expensive, at least that is what I see in my home town.
Ghashaan
July 13, 2019 at 3:27 am
Good job!
Parasuraman Subramanian
July 13, 2019 at 2:39 pm
Something new learnt from the article; i.e. blue light OK, even when power supply is bad! Well done! Many thanks!
Devon Wilson
July 13, 2019 at 2:40 pm
Great advice. Nothing should be overlooked in electronics. Everything is suspect until proven good.
Yogesh Panchal
July 15, 2019 at 3:39 pm
suranga, Good JOB!
Humberto
July 19, 2019 at 10:13 pm
Well done Suranga. Those e-caps with bad quality are a total disaster.
Hrishikesh
July 26, 2019 at 5:27 pm
Hi,i am located in mumbai. i am facing problem in local brands LED tv with red lines on full screen.ican you help me to sortoutthe problem.
Master H
August 4, 2019 at 2:17 am
Hmmm awesome tip
Rodrickmakangaphiri
September 11, 2019 at 1:20 pm
I came across no sound,no picture ,replaced backlights the TV worked for week,replaced led driver components ,now working! Can someone elaborate on this circuit?