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Dead Dewalt battery charger repaired. Model: DCB105

By on December 20, 2013
battery-repairing

 

 

 

 

 

 

 

A construction worker brought it to my shop. It was a dead battery charger that does not charge the batteries for the power drill that he uses for his work. He said that he took it to someone else to get it fixed but the technician only changed the power cord but that did not bring it to life.

battery repair

Once I opened the cover and scanned the board with my naked eyes, I spotted a resistor that had a black dot on it. It was red black gold and gold. That means it was only 2 ohm resistor and also a fuse. When I measured it with my meter, it was open.

 

I replaced that with the same exact value and powered the machine. That did not bring the charger back to life.

battery repairs

The main power capacitor was not discharging at all. Even when I unplugged the power source, the capacitor was still holding the 300 dc volt there. To be on the safe side, I had to discharge it before I continue working on this charger.

Later on I found another transistor that was shorted out. The part number was BV42. It is unusual transistor. When I checked the specification on it, it was NPN, 700 volts with 2 amps rating. I could not find one like it in the stores. I checked with some technicians that I know in my area and I was lucky to find one. He had exactly the same charger but with a different problem.

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These were the faulty parts that I found in the battery charger. Replacing both the resistor fuse and the transistor brought the battery charger back to life.

To me, it was strange how the guy send it to be repaired and the technician  replaced only the cable. It was a guessing work for him. It takes only one minute to find out if the cable is faulty or not. Obviously , the cable was in good conditions because by checking, I was able to find the actual fault with this battery charger. When I checked the original cable that came with it, it was not faulty, it was just dirty and looks old.

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Make sure you test things out and not to be fooled with how old or dirty the part look like. Mission accomplished.

 

 

Waleed Rishmawi

waleed

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.

Please give a support by clicking  on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.

By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.

 

 

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6 Comments

  1. roy harel

    April 25, 2017 at 11:45 am

    It was nice to read!
    I am searching the net trying to understand what is the principal for converting dewalt Charger from 110v input to 220v input.
    Mybe here is a good place to ask

    Likes(1)Dislikes(0)
    • hac

      June 9, 2017 at 11:33 am

      Hi sir, you can do what you want with a electronic triac dimmer.
      Adjust your dimmer to minimum, and plug a light bulb on it.
      Place an RMS multimeter on the bulb and adjust your brightness corresponding at 110 V RMS. Don't touch the adjusting anymore and place a new bulb with different power on the outup, and check again if there is the same voltage on it, meaning 110V.If yes, that's ok, if not, stop all.
      At this point, place a 10 ohms power resistor in serial with the 11O Volts charger and plug it to the dimmer, and the 22OV. The charger will work now on 220V

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  2. That Guy

    June 21, 2019 at 10:43 pm

    Another great Palestinian, making things work again with nothing but his brain and some discarded parts. Solidarity, comrade. ✊

    Likes(1)Dislikes(0)
    • Ozer

      September 10, 2019 at 9:38 pm

      I need dcb105 charger diagram/shema.can u help us about that

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  3. stanley rose

    March 16, 2020 at 10:44 pm

    Hi! I would like to ask the details about R12, R14, R35, R34, R20. Hope you can help me

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    • Edd Whatley

      October 18, 2020 at 11:29 pm

      A bit later add on . . .
      but here is the specs on the " mystery " transistor that you encountered.

      https://alltransistors.com/pdfview-s.php?doc=stbv42&dire=17

      In the future a cheap "free " parts source might be one of the good transistors used in CFL lamp boards that you might have held onto for "parts".
      The lowest of the very commonly used 13003 series numbering use that same TO-92 case, but I can not confirm the same basing at THIS instant .
      The higher end 13003-7 series use the somewhat large heatsink tabbed TO-126 case.

      That's it . . . . .

      73's de Edd . . .

      .

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