How To Repair Toshiba LED TV With No Power Symptom
Customer sent to me this 32″ LED Toshiba TV with the complaint of no power. I have checked the TV and it was indeed no power and I had to removed the cover.
Once the cover was removed I could see the two main important circuit boards which is the power and the mainboard-see the photos below:
The main fuse was checked and it was good and there was no sign of any burnt components from the visual inspection. I powered On the power supply and checked the output and all the output voltages were zero volt (photo below) which indicated the power supply is the cause of the problem.
In order to safely check electronic components in the circuit board, one must discharge the big filter capacitor first-see the big capacitor in the below photo and it was rated as 150uf 450 volt. This discharge is for precaution purpose.
After I had discharged the big filter capacitor, I started to check on the secondary output diodes. Checking one of the secondary output diodes revealed that it was shorted-photo below:
The shorted diode was actually connected in parallel with the other two output diodes. I soldered the shorted diode and powered on the TV just to check if the power would work.
As expected, the power LED was lighted and this confirmed only one secondary output diode shorted.
After the replacement with a new diode and powered On, the below picture is what I saw. This means this Toshiba 32 ” LED TV with no power symptom is only caused by a shorted diode and nothing else.
By the way Kent just launched his latest Ebook in OLED/LED/LCD TV repair tips version 5-you can check out the link HERE.
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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Note: You may check out previous post about fixing active speaker in the below link:
https://jestineyong.com/how-to-repair-no-power-problem-in-hi-fi/
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Albert van Bemmelen
February 20, 2017 at 8:03 am
Good and fast repair Suranga!
I also again bought recently Kent Liew's and Damon Morrow's E-Books on TV-repair.
Sadly they both do not mention any European TV sets. A Samsung UE39F5000 is for instance not mentioned. And without decent Service Schematics their use is limited. Especially when only small given solutions are given for other countries TV sets. I couldn't find or buy a Service Manual for the above mentioned Samsung TV, which would no doubt be of much greater use. And the Samsung UE39F5000 sets are well known for their bad functioning if we read the Forums about them.
suraga Electronics
February 20, 2017 at 7:50 pm
Hello. Mr-
Albert,
Thank you So Much !!
Calum
February 20, 2017 at 3:15 pm
good job bro
Mark
February 20, 2017 at 8:04 pm
Hey Suranga,
Great it was a simple repair. Was it worth changing the other secondary diodes in that area? They would have been running the same amount of time the faulty one had. Just a thought.
Well done on the repair.
Ulises Aguilar Pazzani
February 22, 2017 at 11:38 am
MR Suranga, nice repair and easy
Yogesh Panchal
February 22, 2017 at 9:14 pm
Good Job!
Suranga.
Humberto
February 28, 2017 at 1:59 am
Great and effective repair Suranga
sherly
March 3, 2017 at 8:39 pm
Hi suranga..i like the electronics repair subject.....
Parasuraman S
March 7, 2017 at 2:42 pm
Excellent job! Very experienced way of handling the servicing!
Mathew Charles Karonga
April 7, 2017 at 7:32 pm
Well done sir I appreciate your articles for their clarity and stages your took to accomplish this repair to me It has been helpful for improving my time management in any repair.