How to Repair LED Lamps

11 February 2019 

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The LED circular lamp in our dining room  went off suddenly. This is after about 2 years in operation.   One set of two LEDs were found faulty.  This article serves to share how to troubleshoot and repair this LED module.  The procedures described here can be used also on other types of LED lamps

How LED Lamp Works?

Unlike normal fluorescent lamp,  LED lamp does not have fluorescent tube nor ballast;  instead,   it has the following components

1.   The LED element;

2.   The LED  driver;

3.   The Aluminium heat sink.  

As current flow through the LEDs,  it causes the LEDs to give out lights.  Depending on the size and power of the lamp,  a  LED driver can supply different wattages to several LEDs arranged in series.    In this case for the 18 watts circular lamp,  the driver will supply 48 Volts to the LEDs.   Each LED will operate at around 3 to 3.6 Volts and consume around 0.5 watts of power. There are about 36 LEDs in this 18 Watts lamp.   The LEDs are arranged in an array as illustrated in the following

What can usually go wrong?

The LED driver consists of very few components as shown. 

It is unlikely to have broken down as it is quite robust and reliable.   Most likely the LEDs are the ones at fault.

What’s Needed?

There is no special and expensive tools needed.  

Description	Remarks (doubleclick to enlarge pictures)
1.  Two numbers of 1.5 Volts AA or AAA battery,  improvised as LED tester	Solder them up in series as shown
2.  LED elements	They are available from various online website such as AliExpress.  100 piece of common type of LEDs cost less than USD$1/=
3.   Soldering tools	Soldering irons and solders

 Repair Step by Step

Description	Action	Remarks (doubleclick to enlarge pictures)
1. Inspection & testing	1.  Go through by inspecting the LED one by one. 2.  One could also light up the LED by touching their ends using the improvised LED tester.   The pair of LED should light up unless they are faulty.	Faulty LED can be easily spotted by its burnt mark as shown
2.  Unsoldering	1.  Unsolder and remove the faulty LED from the board using the soldering iron.   2. Carefully solder the new LED after having identified the locations of the Anode and Cathode and place it back into the correct position	The cathode is identified by an additional plate at the end of the tips as shown
3.  Final Testing	1.  After soldering,  test the repair  using the improvised LED tester.