My Projects

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Published 31 Mar 2018

Philips LED Bulb


I brought a number of Philips LED (light emitting diode) bulbs to replace compact fluorescents, with the expectation of long bulb life and low power use. But one failed within a few months, little used.

Philips 10.5W LED Bulb
Faulty Philips 10.5W LED Bulb

Overview

Bulb label The faulty bulb, which has a standard 240V bayonet fitting, was labeled :


          10.5W 6500K 1055lm 95mA
             220-240V 50/60Hz
           Made in China  6EV
             9290011648B1
             

Hardware description

Bulb with dome removed These bulbs have an opaque plastic surround that comes halfway down what would normally be the actual glass bulb area. So the “bulb” is actually a semi-circular translucent plastic dome on the end - it doesn't emit any light upwards. I used a hacksaw to cut through the edge of the plastic dome, all the way around - taking care to only let the blade penetrate the plastic of the dome and not risk cutting any internal structures.

Internally are 13 LEDs mounted on a flat PC board labeled “Entry Bulb G6 19UP 20150924”, “E347474”, “LDB-08”. The only other components visible are some surface mounted 0 ohm jumpers. Internally each LED appears to have 3 LED chips, presumably red, green, blue and driven with an appropriate balance to provide 'white' light of the appropriate colour 'temperature'. The board has space for 18 LEDs numbered 1 to 19, “5” appears to be missing. Led “12” appears to have been replaced with a bridge of solder, rather crudely by hand. The board appears to be connected to controller electronics in the base via a two pin edge connector, again crudely soldered by hand.

LED boardNormal LED

Fault

Damaged LED The fault appears to be a faulty LED “11”. My first thought was that a soldering iron had accidently touched and melted the LED in manufacture, and that it had subsequenlty failed. But looking at the close-ups it looks like it has split right across, so maybe it ruptured from gas build-up after overheating.

Summary

I haven't finished checking this out, and will have to test the LEDs and trace the fault. I am surprised that there appear to be hand soldered elements in these 'high tech' products.

References and Additional Resources

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