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WL= 15 Volt Zener Diode (Multi DC Output Adapter Faulty)

By on February 28, 2019
power adapter repair wl 24 volt zener diode












power adapter repair wl 24 volt zener diode

The complaint of this Universal AC TO DC output power adapter was no power. The usual power adapter has a fixed output DC voltage but this type of design have several output DC voltages – 12/15/16/18/19V/20/24 volt. You can see the photo below:

power adapter repair

Although the complaint of the power adapter was no power, I have to double check it to make sure there was really no power. Sometimes customer can give a wrong description.

After checking it, indeed it was no power-see the photo below:

no power in adapter

The first I did was to slowly cut open the cover with a cutter. It took me sometimes to cut opened it.

havit power adapter

Once I flipped the power circuit board I saw burnt mark at the power FET leads and the main fuse was blown too.

power adapter circuit board repair

power supply adapter fix

Since the power FET (2N60) was blown this mean I had to check on the corresponding components. All of the SMD components were tested good except one (board location ZD3).

It had a shorted reading and the component marking was WL.

wl smd is 24 volt

From internet search I found that the WL marking means 15 volt- see the chart below:

wl is 15 volt zener diode smd

Next, I simply soldered a new power FET and a 15 volt zener diode for testing purpose but of course had to go through the series light bulb test.

The series light bulb test is  to prevent the components that I have replaced from blowing again, if there is still short circuit in the power adapter. If the power adapter is working then I will remove  the bulb and put back the original fuse.

40 watt light bulb in series

The good news was, it worked perfectly fine and from the photo below you could see that the output DC voltage was 15.93 volt which is very near to 16 volt-job done.

fixing power adapter

how to repair power adapter

Conclusion- If  you want to enhance  your power supplies or even power adapter repair with the help of many tips and tricks, I can recommend Jestine Yong’s ebook in SMPS repair HERE.


This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.

led tvrepair

Click HERE to check out Humphreys ebook in LCD/LED TV Repair


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  1. EJAZ

    February 28, 2019 at 11:04 am

    Hi sir.
    Your repairing article more helpful to me and I several times Learned and applied for Repairing. I founded Very valuable for me. I request to You that teach me. How to Repair Chinese USB mp3 and also mp5. Digital display problems. Its pin volts. Power input problems to main decoder ic. Audio output problems. Audio DAC TO ANALOG problems. Etc.

    Thanks. Ejaz.

  2. Robert Calk Jr.

    February 28, 2019 at 11:08 am

    Good job, Suranga.

  3. Albert van Bemmelen

    February 28, 2019 at 5:31 pm

    Good clear instructions in this repair about the use of the light bulb for beginners. Sadly in my experience most of these Multi DC Output Adapters are not this easy fixed. Often it is also the transformer that had gone bad! And those can't be easily replaced or repaired.

  4. Joshua Oloo

    February 28, 2019 at 6:17 pm

    That's very educative Mr.Suranga.especially when dealing with SMD components.keep it up

  5. George Greenfield

    February 28, 2019 at 7:17 pm

    Well done Suranga.
    Looks like a real useful power supply.

  6. monim

    February 28, 2019 at 11:15 pm

    really good job

  7. Parasuraman S

    March 1, 2019 at 9:24 am

    Very useful information shared and a professional service!

  8. Justice

    March 1, 2019 at 4:05 pm

    Nice article please keep posting such, they have positive impact on new beginners like myself.

  9. Menda Peter

    March 6, 2019 at 4:30 pm

    Thank you, it is helpful article and very much educative.

  10. Humberto

    March 6, 2019 at 11:00 pm

    Hi Suranga, I really enjoy reading your repair articles. Could you or anyone of this blog send the websites where search information about SMD devices? I already know the


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