Saturday, July 29, 2017

Fake screw! Fake terminal block! And modifying multi-color LED ceiling lamp's default behavior

I've recently bought some LED ceiling lamps that supports multiple color temperature (daylight,warm white and "natural" white) by toggling the power switch as below.

However, I prefer the default color to be warm white instead of daylight as it will be installed in a bedroom and less blue light might help with my occasional insomnia. So I decided to try to modify since it should not be too hard since they LEDs and a constant current LED driver like below.

First I tried to open up the LED driver and have a look at the circuit inside. But when I tried to turn my screw driver on the 2 screws on the orange colored part, it didn't turn at all. Upon closer inspection, it seems that those are fake plastic molded screw!

After a while, I figured out that the entire orange colored terminal block was also fake! 😆
It is just piece of plastic held together those snap-on plastic parts.
Hahaha.. I guess this is not too surprising since it comes from the country that also produces fake rice, fake eggs, etc... 😜

I wonder why they made it to look like the conventional T8 fluorescent tube ballast choke although the PCB inside is actually 30% smaller the plastic chassis. They could have made it simpler and smaller. I could only guess that it is suppose to make it easier for electrical wireman to install without additional training.

Anyway, from the PCB and the diagram on the chassis, I could figure out that it connects to the LED lamp using 3 wires with common-anode configuration. So, it seem like there are only 2 types of LEDs in the lamp (warm white and daylight) while the third color is just simulated by mixing both.

Hence, to change the default behavior, I just have to swap the output for warm white and daylight wiring on the connector.
Originally Red V+, Green V1, Blue V1
Green and blue lines are swapped.
With this simple mod, it defaults to warm white!

Anyway, I have also measured the power consumption of the lamp with my power meter. The box says 24W but it seems that it is only consuming 22.3W.

While I like the idea that it is more energy efficient, it seems that I might be getting short changed as consuming less power means that it might not output as much lumens as stated on the box. Also the power factor seems pretty horrible. For comparison, a good 10.5W Panasonic LED bulb I bought previously measures at 10.9W and 70% power factor.

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