Defect In 1117-3.3V IC Drove HAIER LED TV Model LE22B600 To Intermittent Standby
This LED TV belonged to the hospital where I work. It was brought to me with the complaint that the TV goes off intermittently. After bringing it home, when I checked up, it was actually going to standby mode intermittently. I opened the TV and subjected it to thorough cleaning. I observed a horizontal line, which could be ignored as it did not impair the vision, but definitely an indication of a future problem in panel.
After checking and finding that all output voltages were ok, and the secondary voltages on the board were ok, I wondered what the cause was! I even raised the volume to full, as speaker shorts can cause such a problem. But the TV did not go to standby on full volume. The defect therefore was elsewhere!
As I could not guess what could be wrong, I took help of my techie friend, who told me that the 3.3V regulator ICs are prone to be defective on a long run and the best way to check was supplying a 3.3V to the output point, from an external power supply. I had a 12V, 5A adaptor with adjustable voltage control. I set the output to 3.3V and wired it to the point.
I allowed the TV to be on for almost an hour and it did not go to standby, proving that the IC was the culprit. So, disconnected the power and replaced the IC.
Then allowed the TV to run for several hours, before closing the back cover and making it ready for delivery to Hospital.
Mission accomplished quicker than expected and satisfaction got collected. (Thanks to my techie friend).
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Albert van Bemmelen
September 9, 2023 at 2:23 pm
Also this quick and easy repair was interesting!
I wonder if this bad 3v3 regulator could have been detected by measuring its temperature?
Parasuraman S
September 9, 2023 at 10:23 pm
It was having normal temperature only, which technicians like me who do not have a thermal detector, check it by touch. Many thanks for your expert comments, dear!
Waleed Rishmawi
September 9, 2023 at 7:07 pm
when any output is missing and supply the missing voltage from an external power supply and everything works I just jumb with joby. recently I have been doing this approach in welding machines when the 24 and the 5 volts are missing to run the screen and fan. thanks for sharing my friend and keep up the good work. have a blessed day
Parasuraman S
September 9, 2023 at 10:24 pm
So, we are progressing parallelly! That's great news! Many thanks for your comments, dear friend!
Tito Kanshulu
September 10, 2023 at 4:31 pm
Impressive and educative Sir. Apart from high temperature, did the regulator show any short or leaks using meter?
Parasuraman S
September 10, 2023 at 5:49 pm
No such indications at all. Many thanks for your comments!
Imoudu.O
September 11, 2023 at 12:10 am
Thanks for friends helping hands you usually get when in a tight corner,I have gain another knowledge from you,thanks sir.
Parasuraman S
September 15, 2023 at 7:18 am
Many thanks!
lloyd
September 11, 2023 at 4:12 am
very good
Parasuraman S
September 15, 2023 at 7:18 am
Thanks!
Yogesh Panchal
September 16, 2023 at 5:38 pm
Good Job! Sir,
i found some time Vertical & horizontal lines are because of T-Con/scaler board. May be some component weak or panel Cable is loose.
Parasuraman S
September 18, 2023 at 4:02 pm
Yes, possible! Many thanks!
Jemba Alex
September 23, 2023 at 6:12 pm
From Uganda,thank you so much Sir
Parasuraman S
October 13, 2023 at 5:36 pm
You are welcome!