Identify this please

Discussion in 'General Electronics Chat' started by cobology, Sep 17, 2009.

  1. cobology

    Thread Starter New Member

    Mar 4, 2009
    hi all been ages since i posted here but just bought an acer aspire laptop (faulty) basically it has no power at all no lights or anything messing on today and noticed when i plug the power inverter into the laptop the green light on the actuall inverter goes out ,unplug it from the laptop and it comes back on so decided to strip it thinking dodgy power jack but upon opening it the jack is on a lead and plug not directly soldered to the board like most so it ruled that out but messing with the M/M i found the item in photo attached to be open circuit there is another one on the other side of the board which shows closed circuit ,so thinking this could be down to part of the problem? only thing is im not sure what it is any ideas it is white in colour with just a number 7 written in blue nothing else:confused: its about 4mm long


    cheers all
  2. bertus


    Apr 5, 2008

    Next to the component it says PF1.
    It could be a polyfuse. ( a silicon fuse that resets when the power is removed ).
    When you measure it (without the power connected) it should read a low resistance.

  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    It's not a poly Bertus but just a SMD fuse, I am sure of it.
    Try bridging it with a fuse wire rated at the adapter current.

  4. mkbutan

    Senior Member

    Sep 30, 2008
    Last edited: Oct 5, 2009
  5. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    sounds like your over currenting on the supply. Confirm by measuring for voltage when the light is on, then again when you plug it in and light goes out. If you loose your voltage, your in current shutdown. It could be a faulty supply so having a second unit to confirm would be nice. if you try to power a resistor only, computed to consume the rated current, your supply should hold, trash if not.

    If supply is proven, I would unplug all your peripherals and remove your memory, then try again to see if light remains on. If so, removing power each time, plug one thing back at a time to find the culprit.

    If not, check to see if futher items can be removed, ie; wireless, video, etc, and try again.

    If your down to bare bones and your still loosing your supply, you can introduce a resistor (same as before) into your supply line to maintain it without tripping. Then quickly go over the board looking for a warming device/component. Don't do this too long or smoke may ensue. I usually use my upper lip as a temp feeler.
  6. cobology

    Thread Starter New Member

    Mar 4, 2009
    hi guys thanks for the input i did the things you have all suggested i have another supply and that does the same thing so it rules out a duff one, had just the bare board plugged into the power and still same thing so definatley a duff board just a case of where though and im no expert in electronics lol so thanksfor everyones input and suggestions once again