Intermittent Problem In 40 LED Philips Light Solved
This 10W, 6500K, 1000Lm lamp was in use in my kitchen. Recently the working was intermittent. So I decided to open it and check it up. In order to open the lamp, we need to remove the cover, by prying it open from its sides. Then unscrew two screws that fixed the 40 LED panel, pull out the PCB from its slot to the extent it comes out. The PCB has two AC input wires that are very short.
Probably, the PCB is inserted with the AC wires coming out at the contact end of the bulb holder, and these two points are soldered at the final stage of assembly. The lamp can be tilted to adjust the light. The following pictures would give you an idea of its construction:
I have given additional snaps for you all to know the value of components used in the circuit, so that in case there is a failure and the component is burst, you might be able to know the value.
As I could see that it was a problem of dry solder on the PCB, I patched up all the solder joints and cleaned the PCB thoroughly:
I gave a temporary connection of AC input and LED panel and switched on. It was working well. When I checked the voltages at the base of the 47/160V capacitor, it was 120V. The number of the IC used in the PCB was found to be 9763B, without any prefix. Though I tried to fetch its datasheet, I could not find it. In order to make reassembly easy, I extended the AC input wires and inserted the PCB, and screwed the LED Panel in its place and switched on power. As I found it was working very well for a pretty long time, I fixed it back and put its cover in place. My wife was happy to have got back her kitchen light.
As usual, this work too got qualified to get into my ever growing satisfaction bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 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 repair article below:
https://jestineyong.com/shorted-diode-and-bulged-capacitor-in-philips-crt-tv-repaired/
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Albert van Bemmelen
August 20, 2019 at 3:22 pm
I guess that although Leds are very energy-efficient they also produce some heat that can cause problems with wires getting hot or maybe melting solder. Especially at the pcb where the diode bridge rectifies the incoming current. But it probably was bad soldering and bad manufacturing that in time caused the intermittent problem. But don't rule out any broken SMD resistors that in case they act as unstable component can cause these problems too. I know this from my days when I fixed portable Bar Scanning handheld devices at a company called HHP in Eindhoven. Where we tested each tiny resistor with our soldering Irons on broken resistors by heating on side while watching if the part separated from the still soldered other half side. Or if it was loose on its solder metal end caps.
Parasuraman S
August 20, 2019 at 9:02 pm
Yes you are right! Good tip on checking dry solder of SMD resistors.
beh
August 20, 2019 at 4:07 pm
well done and the good job .these days I am struggling with unknown smd transistors on the mainboard of telephones. cheers........beh
A L PANDIT
August 20, 2019 at 10:20 pm
Dear Sir,
I have downloaded driver IC datasheet Pdf by adding prefix Sic. I am very much interested to go through all your repair articles on this site. I love the way you represent with minute details.
Regards,
A L Pandit
Parasuraman S
August 26, 2019 at 9:56 pm
Thanks for the tips. I could download it now.
Robert Calk Jr.
August 21, 2019 at 5:12 am
Good job, Parasuraman!