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CFL Bulb Repairing Tips- You can Do it

By on June 27, 2016
how to repair a dead cfl bulb










I have replaced one new CFL Bulb on my desk yesterday and it went off suddenly, so I arranged another CFL and it brighten my desk. I need to find out what went wrong with this dead bulb since repairing is one of my professions.

I opened the CFL Bulb with the help of a hacksaw and a flat screw driver. It was easy to open and no damaged to the plastic body.

cfl bulb repairing tips

On visual inspection everything seems ok. On PCB there was no physical damage and burning marks. There was a 68 ohm resistor that act as a fuse and it was tested Ok.

cfl bulb repair

Next, I checked on the surrounding components and circuit with the help of my multimeter and everything seems to be working fine which include the two HIGH VOLTAGE FAST-SWITCHING NPN POWER TRANSISTOR 4202BD and surrounding diodes and resistors.

how to repair cfl bulb circuit

Till here I did not found the culprit while handling the bulb I visualize black mark on CFL Bulb

how to repair burnt cfl bulb

 I have removed the tube Connection form the PCB for testing the filament continuity.

(Don’t check continuity on the PCB board because the nearby components can misled the reading).

On testing continuity of the filaments  …………

repair old cfl bulb

( If it shows some low resistance less than 20 Ohm that means filament is ok) so finally I found the culprit but for confirmation I do not have any tube for replacement hence I marked on the remaining body of the bulb as assuming working ok with reference date and kept it by side till the arrangement of working CFL Tube  arrived. Thanks!


This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.

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  1. Anwar Shiekh

    June 27, 2016 at 9:10 pm

    It is good we now have LED lights as an option as they seem more efficient and to have a longer life.

  2. Parasuraman S

    June 27, 2016 at 10:16 pm

    Great! From my experience, I never pry open a CFL if it is found black. But sometimes salve the board. Needless to add that it is dangerous to handle CFL and disposing it off, is also very difficult, due to environment pollution (poisoning!)

  3. Albert van Bemmelen

    June 27, 2016 at 11:20 pm

    Thanks Yogesh.
    My brother saved me dozens of those CFL Boards after the Lights went defect and the glass tubes were disposed of. Often the Transistor pair (in a kind of multivibrator circuit) are 600 Volt types.
    Because my brother says he is living closer to a Power Plant his House Main Voltage is higher why many CFL Bulbs do not survive for more than about 8 months. So as soon as the HV Power Leds are introduced I will be able to make new LED Lights (LOL).

  4. Paris Azis

    June 28, 2016 at 4:22 am

    Hi Yogesh

    This is the normal case of failure of a CFL. Well, when they first appeared in the market and until I learned about their function I was opening every defective one I could find! I am not doing this any longer but I still keep some working PCBS of them...They are capable of lighting a 40W fluorescent lamp perfectly and immediately (no delay at start up). Nevertheless the full brightness comes after around one minute. I suggest you to try it! It is an interesting experience full of fun!

  5. beh

    June 28, 2016 at 2:39 pm

    Hi Yogesh
    yes the ccfl lamps also are repairable and i did this also i have many
    pcb s and salvaged part as you did thanks for reports ..

  6. Henrique Jorge Guimarães Ulbrich

    June 29, 2016 at 3:30 am

    In principle, a CFL lamp shall work about 10000 hours (at least is that technical literature say...). However, in the real world, I have seen lamps with too short lives. Recently I bought 3 identical lamps to be installed in a chandelier of my home. One of them lasted about 3 hours. The second one lasted a few days. The third one burnt some time after. By coincidence, the commercial representative for my contry is in my city (of course, China made...). I visited them and they replaced the three lamps without discussion. For nothing: these three new CFL lamps soon suffered from the same destiny - they are now laid aside, waiting for some attention from me. Undoubtedly, a typical case of extremely bad quality product. My hope is that this do not happen in the future with the LED products now being used.

    • Paris Azis

      June 30, 2016 at 5:56 pm

      It seems that you are hopping in vain Henrique. LED lamps suffer the same failures because of the same causes: overheating of the (air tightly closed) electronic circuit which is the main and common cause between the two technologies and bad component's quality which is directly connected with their market prices. So the net result is the same no matter the much higher longevity of the LEDS themselves against the gas filled lamps...
      Just keep in mind that good old song of ABBA ("money-money-money") which explains much about the topic!

      • Obdulio

        May 21, 2018 at 3:12 am

        I perfectly agree with you, in spite of the LED endurance, the lamps suffer from bad components and bad designed heating solutions. I'm still waiting to see a LED lamp which

        I would add that all the LED lamps sold in my country comes with a guarantee, but the buyer must keep the invoice and contact the supplier. In practice, almost anyone keeps the invoice, so, the seller doesn't need to replace the defective lamp.

  7. suranga bandara, Suranga Electronics

    June 29, 2016 at 2:38 pm

    Hi. Mr- Yogesh,

    Thanks ! Your Repairing Tips.

  8. Robert Calk

    June 29, 2016 at 7:14 pm

    Good job, Yogesh. Thanks for sharing the article with us.

  9. Humberto

    June 30, 2016 at 8:39 pm

    Good job Yogesh. Congratulations.

  10. wyxchari

    May 23, 2017 at 12:30 am

    Try shorting pins:

  11. Godfrey hawkins

    January 5, 2018 at 8:46 pm

    I have just repaired a CFL bulb but guys take note of the power bridge,the NPN switching transistors, 60 ohms resistor which act as the fuse,, i advice you to use a 100W bulb to act as a fuse when repairing.... THANKS


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