How I solved Onida Smart 42 inch Led Tv Shut Down Complaint

Hello  welcome to the world of electronic repair article   Today's topic is how I repair Onida LED Smart TV having a common back light shut Down-problem. LED/LCD back light issue is common in almost TV'S and LED/LCD monitors.

I have repaired many N number of TV's/Monitors related to shutdown in my career.   some of them are already published in my electronic repair article

One of my friend had a shutdown problem in his Smart TV   the model  is Onida  LED  smart 42 inch  according  to his  input  TV will be running around 2 to 3 hours  and go to dark mode but the audio is audible  by reciveing this complaint  I came to conclusion that it is particularly a back light issue . Now my concentration is  on the back light area of the television.

  I  gone through the data sheet of the given IC and  the topology involved on LED Switching and  parallely gone to the visual inspection for the PCB &  noticed the black burning image under the capacitor which is shown in the photo this is concluded as a primary clue to accur the fault.

please go through the below snap for the your understanding.

FIG1. A burning symptom on the PCB DUE TO MOSFET defective



 Fig2.A Typical LED Drive circuit

According to the snap and  visual inspection tried to debug the  reason for the shut down and the culprit  could be only on this area.

As a primary clue checked the mosfet by cold test using my RS115 Fluke multi meter which is found ok, then question in mind why black burning mark on the PCB???.This  is done because SMD mosfet is mounted on exact opposite side(under side of black mark area).

Even though my meter reading mosfet  found ok I suspected leaky or defective on this smd MOSFET and made my mind to run the TV to check thermal impact on the  SMD surface.

Yes,my guessing was correct out of 4# two mosfets are getting very hot on it's surface,because of this a burning symptom is clearly visible as shown in fig1. it's a clear evident . When mosfet goes hot resulting excess current drawn and Boost circuit switched off resulting protection mode.Useally this activity will happen in fraction of seconds and very difficult for monitoring with our test instruments. Please go through the SMD Mosfets Shown below based on above observation finally concluded mosfet faulty.

FIG3. SMD MOSFET Getting over hot after 4 to 5 minuets run

Any way mosfet faulty was identified but my next task is to replace the same component.

but unhappy news is that exact mosfet is not available in the market.

Usually CODES on the mosfets  body says the type and typical applications when Googled on an internet.

Now, I don’t have any option searched equivalent mosfet by referring data sheet,selected and mounted all the four same batch code and type mosfets as shown with new through hole component IRFU210.


FIG4. IRFU210 Mounted instead of SMD Mosfet

FIG5. Through hole mosfet Soldered in place of SMD mosfet

After this started test running about 8 to 10 hours. Back light circuit started working fine without any interrupt .felt very happy thinking that

this activity  is success and got more confident because the temperature has not raised even after non stop run after 10 hours without heat sink. Yes,my repair is successes, tv worked perfectly and the back light section circuit re-gained the life. Finally I re-checked the back Led voltage got 120volt DC which is normal.



FIG6. ONIDA SMART LED TV Ready for Delever after Repair

Customer felt very happy after watching TV in my work space and  delivered . This is the story how I repaired the 42inch Smart Onida  LED TV. Let us meet in the next session for one more interesting topic.


With Best Regards
Basavaraj BM