Detecting which component failed in laptop power circuit

Discussion in 'General Electronics Chat' started by Korime, Aug 2, 2015.

  1. Korime

    Thread Starter New Member

    Aug 2, 2015
    Laptop powers up from the battery but it does not from the charger and it doesn't charge the battery either.

    I have measured voltages on power circuit components (see in the attached image).

    Or for better resolution, download pdf schematic file (page 6) - attached, or from:

    In "blue" are voltages measured when only charger is attached. In "green" are voltages measured when only battery is attached. In "italic" are voltages that prevail when both charger and battery are attached.

    "6-7V" means that multi-meter is reading unstable voltage which goes from around 6 to around 7 volts up and down. Does this indicate malfunction and of "Q6003"?

    If not, which component/s are not working properly and need replacing?

    Update: I have replaced Q6003 and everything stayed the same, so it's not that component.
  2. Gdrumm

    Distinguished Member

    Aug 29, 2008
    Have you tested the charger itself?
    It should be around 19V, with the inside sleeve of the barrel tip being positive.
    If your meter tip is too large, insert a paperclip into the barrel (inside the sleeve).
    Be careful not to arc across + and -, as that will surly short out most chargers.

  3. Korime

    Thread Starter New Member

    Aug 2, 2015
    Hi Gary,

    If you look at the photo or pdf I posted, you can see that there is 19.4V receiving from the charger. I had tested the charger though before anything else, and it's working as it should.

  4. ericgibbs

    Senior Member

    Jan 29, 2010
    A very common fault is a break in a wire to the charger socket located inside the laptop.
    Many of these sockets are just a press fit into the plastic which allows the socket to move every time you plug in the charger, so eventually a wire breaks off the internal socket connector.
    I am repairing a 3rd laptop this year at the moment with the same problem.! Its worth checking the socket.:)
  5. Korime

    Thread Starter New Member

    Aug 2, 2015
    Hi Eric,

    Yes, the wire was the first problem. At first I didn't get any voltage through, so I fixed the wire. Now, I get the voltages - as per my schematic, so wire is not a problem anymore.