Tuesday 23 April 2019

HOW TO REPAIR LED LAMPS



    How to Repair LED Lamps



     

    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.  
    https://2.bp.blogspot.com/-Yi5WL5U9yVU/XGDmeynzy_I/AAAAAAAAD4U/TYHNv7DmBNYE45niWDW5-L5_h6U2m-xkwCLcBGAs/s1600/2018-11-13_15h37_11.jpg
    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
    https://1.bp.blogspot.com/-iQ_uNkDG9jg/XGDrNIKLRxI/AAAAAAAAD4g/0OPE9Fi-sAwXiepZjpsJqOHdHNAoTy6ZQCLcBGAs/s1600/2018-11-13_15h04_57.jpg

    What can usually go wrong?

    The LED driver consists of very few components as shown. 
    https://1.bp.blogspot.com/-8qyz-02wFaA/XGDrbyOSJdI/AAAAAAAAD4k/fSiFOWNF_JonCaHq57KgEAsjnyNV7OnbACLcBGAs/s1600/2019-02-11_09h32_01.jpg
    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
    https://3.bp.blogspot.com/-xR_kZVA7DUI/XGDr7NuPVCI/AAAAAAAAD4w/nW2eC8Ih7tkWzyFOOszJ-JtnxaCd-6zvgCLcBGAs/s1600/2019-02-11_10h21_05.jpg
    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/=
    https://2.bp.blogspot.com/-pt-x57K_D5U/XGDs3kHG1AI/AAAAAAAAD5E/_dce_OhiaFE_B8ke995h8tsK8SJ3oeBIgCLcBGAs/s1600/2018-11-13_14h31_56.jpg
    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
    https://2.bp.blogspot.com/-wzVlGrPi_IQ/XGDsFzYxCEI/AAAAAAAAD40/w3QBCJmZrnQV4_f3UjAGbqvN8I_UUeSggCLcBGAs/s1600/2019-02-11_09h33_32.jpg
    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
    https://3.bp.blogspot.com/-jsFoHJ1muqA/XGDtOOcnhKI/AAAAAAAAD5M/ioJuFgO4FbAd5UFhxDfAON1ETYBnNVQfACLcBGAs/s1600/2019-02-11_09h05_18.jpg
    3.  Final Testing
    1.  After soldering,  test the repair  using the improvised LED tester.
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