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attempting to fix my broken laptop charger

Discussion in 'Troubleshooting and Repair' started by foTONICS, Jul 4, 2014.

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  1. foTONICS

    foTONICS

    332
    9
    Sep 30, 2011
    So I have an Acer laptop with your typical charger (120VAC in/ 19VDC out) that connects the laptop to the wall. This morning it stopped working. Using a multimeter I tested the connection between the wall and charger and got 120VAC. Then I checked the end that goes into the laptop and got 14VDC(which is weird because it should be 19VDC) but as I continued to monitor it I saw it dropping fast, all the way until it reached about 3.3VDC, at which point the voltage drop sort of plateaued. At this point I figured I had a bad capacitor or something inside the charger and decided to look inside. I used a dremel and opened up the brick (see pic "charger1"). I didn't see any loose connections upon first inspection. I was about to take off the shielding to probe inside when I decided to check the DCout one more time (see pic "charger2"). I was surprised to see 19VDC coming out of the connection. At this point I plugged the other end into my laptop and it started charging. About 5 minutes into it I looked over and saw the charging light on my laptop not lit so I checked the DCout again and saw that it was doing the voltage dropping that I first saw.

    At first I thought this was a capacitor issue since the voltage was dropping but could this still be the case since it seems to start and stop outputting the desired voltage even when I'm not moving any wires or disturbing the unit?

    Could a loose internal wire that I don't see be causing this?
     

    Attached Files:

  2. foTONICS

    foTONICS

    332
    9
    Sep 30, 2011
    UPDATE: So I checked continuity across the + and - wires on the DC side and my multimeter beeped. I removed the cord and the two lines still beeped but I couldn't get them to beep all the time. This makes me think there is an internal short somewhere. this brick is packaged pretty tight so I'm now deciding whether I should investigate and repair for peace of mind or buy another one
     
  3. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    To confirm, you have unsoldered or cut the 19V wire from the power supply that goes to your laptop?
    And you are getting a short across this wire? Or across the +/- contact on the power supply?
     
  4. foTONICS

    foTONICS

    332
    9
    Sep 30, 2011
    I unsoldered the wire that goes from the 19v side to the laptop. I then used the multimeter to check for a short where the cord used to be and I found an intermittent short (The 19Vout side on the charger).
     
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