Recently I found one LED flicker in my home, it is annoying! What the hell! I can not stand with the led product. Oh my god. Considering it companied with me for 3 years, burn yourself, emitting in the night, I forgive you, but I want to go deep inside to find what is going on! Though I am not an engineer!
If I am newtown, what would newtown going to do?
If I am edison, then what will he going to do ?
If I am ……
So finally, I try to tear down the light! After 6K to 7K operations, I assumed, the LED bulb is not easy to tear down.
The table underneath is the character of the LED bulb, I just remember it is a gift from my brother, he take , though there is no label, no package.
|Input Voltage||220 – 240 vac|
|LED Package Type||SMD|
|Way to connected LED||Connector|
Here is the light bulb underneath, it has a glass diffuser.
In the most countries, you can find the LED bulb with glass but not U.S. and Canada, you know, because the LED bulb standard is total different! According to UL/CUL 1993, all the LED bulb must to do the drop test from the height is about 1 meter.(Rear more: UL/CUL 1993 Test)
Go down to business, let us begin the journey.
The whole LED bulb dimension is 107 mm by 45 mm. The glass diffuser is longer than housing and lamp base! It looks odd! You can find something inside the top of diffuser. I do not take a picture for this. After destroying the glass, you will see below picture. Be careful when you do the similar thing.
You can find 4 PCS LED on the each side. On the top, there is a plastic fixture. There is the odd when I see the top of the diffuser. What is reason to employ with these type of LED package? What is the consideration? Is this good for efficiency? What is the price of the type LED package.
Remove the plastic part, the 4pcs LED is easy to take apart, the gule has been dried-up. Yes, it has been yeras.
Now, here is the LED part disassembly, the driver output wire solder on the PCB Board, 4 connectors on the PCB, fixed on the enclosure. the heatsink looks crazy!
Next remove the screw by tool, found gule there. The red wire on the screw.
The housing include 2 parts, outside of the housing is plastic, inside layer is metal heat sink. It the inside surface of plastic looks a bit black, crisp. OH, it is rally hard to remove the plastic housing, the metal heat sink and plastic seem bond together.It seems Family part.
Now turn to driver view, it looks old from the color. The letter 2013-9-3 shows its production date. When remove the potting, the skin of the caps came off. When you see the capacitors near the input wire, you will find that the number writes 125C. Why do the manufacture would use this high temperature capacitor?
I found the red wire has been black over time. If the lamp operate for years, it seems the temperature more than 90c. It is dangerous.
What is going on with Input wire?
Here is the BOM List
|Diffuser||1 pcs , glass, high Transmittance|
|Enclsoure|| 3 layers, outside is plastic,
middle is Al, inside is plastic
|Lamp base||1 pcs|
|Driver(Potting)||Completely wrap the driver|
|Metal Board||1 pcs, fixed on the inside of the enclosure|
|LED||4 pcs, 30 mm by 0.5 mm,cremic|
|Top Plastic Fixture||1 pcs, physics fit the 4 PCS LED on the top|
|PCB Board||E239807, 94V- 0|
|L/N Input Wire||S1:black colorwite, S2:white color wire|
|E capacitor||C1, 3.3uF, 400V, 125C|
|E Capacitor||C4, 7.7 uf, 100V, 105C|
|Diode||D1 – D2|
|SMD Capacitor||C1 – C6|
|SMD Resistor||R1 – R9|
|Output Wire||S3：yellow wire, s4:white wire|
Then going to the question; Flickering.
When I cut off another Lamp Bulb, turn on the LED bulb, something was found. One PCS LED is dead. OMG. So the LED bulb is dead due to one PCS LED damage.
What is going to deal with this situation? What is the industry failure module?
In order to accurately characterize the reliability performance of any product, it it important to identify and understand the failure modes that affect the life time. In the case of LED lighting products, we are generally familiar with the lumen depreciation of LED packages which will eventually result in the light no longer being useful. We are also aware through experience with traditional lighting as well as LED lighting that another gradual change, color shift, may provide a limit to lifetime as well.
The LSRC has reviewed studies intended to identify potential failure modes and provide additional understanding of product life. We reviewed the results of some highly accelerated multi-variant tests and other avaiable data to learn which failures may be significant and how those failures might be accelerated. Some of the information on failure modes comes from a eries of highly accelerated tests exected by RTI International with the help of adoe funding on a limited number of product examples. Other information can be derived from the DOE testing associated eith the Philips L Prize-winning LED A-lamp. Systematic field data is of very limited availability but does provide some additioinal insight into those areas that should recive some attention. Still further non-public information comes from the experience of members of the LSRC and infoms the discussions about important failure mechanisms. Members were asked which failure modes they most frequently observed; the resulets are summarized in below picture.