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Faulty Transistor Caused LED Blinking

By on December 29, 2021
emergency light repair

As I was going to buy something from the nearby market, an old man who is a certified electrician asked me if I repair an emergency LED light devices because they are so cheap to buy and he was wondering if I am willing to waste my time on it. I smiled and said; of course I will take a quick look at it and see what I can do.

how to fix emergency light

The device was already open and I could see some work done inside the device.

As I understood from the man that when he connects it to a battery source, the LED lights blink on then off and stays that way.

how to repair led emergency light

I powered the device up and right away I could see the LED light indicator that it was charging. I measured the reading at the positive and negative terminals of the wires that go to the battery; I got about 13 DC volts there which is another indication that the right voltage is reaching the battery for charge.

how to fix a broken emergency light

Once all these tests were done, I started to check if there are faulty LED lights because it there was one light that is shorted, it will cause the other lights to shut down but all lights checked fine.

fixing emergency light

I could see a fuse resistor and a glass fuse on board but both of them checked fine. I traced the wires that go to the LED’s board and I could see three wires, black for ground, red and blue for positive voltage. The device has two light settings which require two positive wires connected to the LED’s board.

I found a transistor with part number Ss8050 shorted (marked with an arrow) and I believe that was the cause of this device not coming on.

ss8050 transistor shorted

ss8050 transistor datasheet

Click here or the above photo to access SS8050 Datasheet

I took that transistor off board for testing and sure enough it was shorted and needed replacement.

These kinds of transistors are found in the microwave oven boards and since I have plenty of them in the shop, I replaced it right away and powered on the device. Take a look

emergency light fixed

Mission Accomplished.


This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous article on Movement Drift On A PS4 Controller Repaired and Maintained



  1. Babu M S

    December 29, 2021 at 10:30 pm

    Your made old man to happy.My best wishes for this kind of act. Thanking you for sharing such a repair.

  2. Albert van Bemmelen

    December 29, 2021 at 10:50 pm

    Keeping spare parts in stock is always a smart move. Especially in these days of chip shortage! Many deliveries are put on hold and now even the increased energy prices are causing new problems too. Good thing you were able to fix another device at hardly any cost.

  3. Anwar Y Shiekh

    December 30, 2021 at 1:35 am

    I find repair to be very satisfying, but it must be hard to make a living.

  4. Gary Gemmell

    December 30, 2021 at 5:20 am

    You are the man Waleed another good educated fix.

  5. Parasuraman S

    December 30, 2021 at 11:03 am

    Well done, dear friend! A naughty transistor was found faulty and your facility could rectify it without difficulty! (Ha! Ha!) (Am I becoming a poet?) (LOL)

  6. Yogesh Panchal

    January 2, 2022 at 5:09 pm

    waleed,Good fix.

  7. Humberto

    January 15, 2022 at 12:32 am

    Good repair, another device saved from the dump.


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