Restored A Lovely LED Surface Panel Light
This LED light belonged to my colleague in the hospital and was brought to me with the complaint that it was found dead. I checked the LED drive and found it was producing the required voltage. So, the culprit was the LEDs. In order to open the lamp, you need to pry open the ring on the top, which are locked to the metal case.
After opening and removing the glass, mask and ground glass type plastic sheet which distributes light evenly (I am not sure of the names I used to describe!), I removed the led strip stuck on the inside.
The inside of the LED driver:
I checked the strip applying voltage from the LED tester, which showed the LEDs were short. Just out of curiosity I counted the LEDs and used my LED Tester to find out the burnt out LEDs and the voltages of the ones that were ok. Found a few LEDs shorted.
Though replacing just only the defective SMD LEDs was possible, I opted for replacing the strip, as other LEDs would also fail one by one soon. Got the replacement strip and checked it with my LED tester and found it to be alright. Peeled off the gum protection and stuck the LED strip firmly inside the slot in the original place where the other was.
Before connecting the LED driver, I did a retouch of all the soldering points and also replaced the two electrolytic capacitors; 6.8uF/400V with 10uF/450V (as I was not having 6.8uF) and 3.3uF/250V with 4.7uF/250V (same reason here too). Cleaned the board thoroughly with IPA. Applied power and checked the voltage output before connecting the LED strip.
Used the soldering iron from my newly added replacement SMD re-work station Kada 2018D+ and connected the +/- wires to the LED strip. The thin bent tip was found very useful for a precise solder:
Applied power and found the LED strip glowing very brightly. The voltage measured was 56V DC. It was safe enough. Fixed the glasses like before and pressed the holding ring to its locks.
Needless to say that the mission was accomplished very well and satisfaction got added to its collection bag.
Special notes: (1) Never ever replace part of LEDs in any LED strips, as the current drawn by new and old might vary and either the other LEDs or the ones replaced would soon fail, making a revisit, leading to customer dissatisfaction. (2) Always spend some time studying the defects thoroughly to know more about it, as part of our progressive education. (3) Always take snaps and note down the step by step troubleshooting done for easy reference later, as and when found necessary.
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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You may check on his previous article on Complex Circuit Of Panasonic Surround System SA-PT860 And Tips For Troubleshooting
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Lynn Blakely
April 29, 2022 at 11:02 pm
Good Job, Parasuraman: I'm thinking your satisfaction bag is getting bigger. There's always a good feeling when a repair is finished.
Parasuraman
April 30, 2022 at 10:07 am
Many thanks! The bag is self_adjusing!(LOL)
Albert van Bemmelen
April 29, 2022 at 11:46 pm
Replacing the old Led strip by a completely brandnew one is an excellent tip! As it obviously also is important when fixing the led backlight of any tv.
Parasuraman
April 30, 2022 at 10:08 am
Many thanks!
Babu M S
April 30, 2022 at 12:53 am
Very good repair work and special notes.Sir I need your help to repair my home theater subwoofer amplifier gives low out put. checked all the components found ok.Replaed out put transisters TIP35candTIP36c,no improvement.What could be the problem.The model number JBL ATX 100S.I am waiting for your advice please.
Parasuraman
April 30, 2022 at 10:13 am
Use an external amplifier connecting input isolated by a 0.1uF cap and touching output at each stage from input to output. Find out the defective stage and check around there!
Imoudu.O
April 30, 2022 at 4:43 am
Good you were able to get a replacement led strip.Thanks for sharing
Parasuraman
April 30, 2022 at 10:13 am
Many thanks!
Anwar Shiekh
April 30, 2022 at 6:42 am
Fixing stuff is so ridiculously addictive, but so delightful.
Parasuraman
May 2, 2022 at 7:41 am
Many thanks!
Tayo
April 30, 2022 at 10:13 am
Very helpful insight about LED chips. I had a LCD TV with a bad backlight. I pondered simply replacing the few LEDs which were bad rather than waiting for a new LED strip to arrive. Just as you said, I came to the realization that replacing a few chips here and there would solve the immediate problem but all the other LEDs would have to be replaced otherwise I'd be taking the TV apart again in the near future to replace them as well. With close to 100 SMD LEDs on these light strips it doesnt make sense (time or money-wise) to do this if the replacement LED strip is readily available at an affordable price.
Parasuraman
May 2, 2022 at 7:42 am
Well said!
Yogesh Panchal
April 30, 2022 at 2:56 pm
Sir,
Congratulations! for SMD re-work station Kada 2018D+ this will help you to do precision work without wasting time & ease of use different size /shape of Soldering Tip. Plastic sheet you are talking about is "Light Diffuser" Use to spread it out or to scatter the Light.
It is difficult to find out type of SMD LED & wattage; I have repaired many LED Bulbs by replacing identical LEDs from same type of Circuit. it is possible only when you have donor circuit.
Parasuraman
May 2, 2022 at 7:44 am
Your articles and comments expose the expertise, experience and professionalism!
Waleed Rishmawi
April 30, 2022 at 4:11 pm
the best way for repair is the replace the whole light strip otherwise the fault will happen again. thanks for sharing. be blessed today
Parasuraman
May 2, 2022 at 7:45 am
You are correct! Many thanks!
Biju
May 2, 2022 at 2:31 am
sir from were you purchased the KADA2018D+?
Parasuraman S
May 3, 2022 at 10:39 pm
Hi-Tech, Palakkad
Anil Kumar V K
May 2, 2022 at 1:31 pm
exellent work sir,have a nice day
Parasuraman S
May 3, 2022 at 10:40 pm
Many thanks!