Monday, July 18, 2011

Repairing LED Bulbs Part 1


What makes up a LED Bulb?

It is possible to repair several types of LED bulb - so don't immediately bin your duds. Over a number of posts I hope to outline the procedure of disassembling and repairing two type of LED lamps, the MR16 12 volt type and the GU10 high voltage type.

 To start the series off, I will introduce the pieces that make up a bulb and show how they are fitted. At the core of most current LED lamps are little LED diodes like the one shown in the above photo. The above unit is a 1 watt warm white LED diode. Similar units come in 2 watts - 3 watts - 5watts - 10 watts etc.

The actual diode itself is very tiny and is encapsulated in a plastic housing with a little lens fitted on top to focus the light. It has a metal backing with which to be bonded to a heatsink. A heatsink is essentially a chunk of metal the purpose of which is to carry away the heat being generated. Heat is the great enemy of LEDs.

LED diode units have a + positive and a - negative lead or wire. They have to have the correct polarity and the correct voltage applied, otherwise they blow very rapidly. In the above example, the negative connector has an elongated slot in it to represent the negative symbol.

Above is a faulty LED diode that I removed from it's "star" or mounting disc. You can see the connectors have been cut through. The diodes are both electrically soldered into place by the two contacts, and also are glued to the disc by a special heat carrying cement.

Above you can see the "star" or mounting plate and the empty place where I prised off the faulty diode. The diode is to the right with the underside or bottom metal contact plate upward and showing. You can also see the remains of the thermal paste on the mounting plate.

The "star" or mounting plate above is common to both the 12 volt MR16  type of bulb and to the GU10 high voltage type. The difference between the two types is in the type of driver circuit used in the bulb.

I will be continuing with this series over the next couple of weeks.


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