Component level help needed please :)

Discussion in 'MacBook Pro' started by SilverD, Jan 13, 2015.

  1. SilverD macrumors newbie

    Jan 13, 2015
    Hi all,
    I'm new here and trying to breathe life into a mbp with board number 820-2879-b. It had a slight liquid spill (very little reached the board) and was very easily cleaned off with isopropyl alcohol and a brush.

    The problem is that apart from a green light on the magsafe, there's no other sign of life. I have a little bit of electronics experience but on a lot more simpler pcbs lol, so I'm out of my depth completely here.

    I've managed to get hold of a schematic and a boardview (this is all new to me) for this and I'm just wondering where to start. I have found that I have 12v on the fuse down by the battery, I also seem to have a 3.3v on other components which I'm assuming is the pp3v3 rail?

    Can anyone offer guidance on where to start?
  2. SilverD, Jan 13, 2015
    Last edited: Jan 14, 2015

    SilverD thread starter macrumors newbie

    Jan 13, 2015
    After a little poking around with a multimeter I've managed to establish that I have my G3H voltage and I have PP3V42
  3. freeskier93 macrumors 6502

    Jul 13, 2008
    This is a litteral needle in a haystack. It could be as simple as a single fried capacitor, but good luck finding it. Do you even have a multimeter that can measure farads? Or measure Henrys (inductors)? Do you have any clue how any of the various other ICs work? Like transistors? Voltage regulators? Etc... Without this kind of knowledge you can't hope to track down what part is fried and needs replacing. Even if you did, do you have the skills/tools for removing and soldering SMDs?
  4. SilverD thread starter macrumors newbie

    Jan 13, 2015
    I don't have a meter capable of measuring inductance or capacitance but
    I have experience using oscilloscopes and have access to one.
    I have had experience fault finding to component level on TVs, amplifiers, switch mode PSUs etc, but admittedly this was a few years ago.
    I do have a fairly solid understanding of how electronic components work, but my question was more aimed at people who fault-find on these everyday, and what procedure they would go through in this kind of scenario.
  5. Samuelsan2001 macrumors 604

    Oct 24, 2013
    And there is your issue

    There isn't anyone who fault finds on these everyday as with everything else these days even the so called engineers just replace the whole logic board, the cost in time is just not worth the cost in materials...
  6. SilverD thread starter macrumors newbie

    Jan 13, 2015
    I disagree. Spending 2 or 3 hours diagnosing to component level beats shelling out up to £400 for a new board. There are logic board repair specialist companies all over the world that do just that.

    Thank you both for the helpful and encouraging comments though.. :rolleyes:
  7. nebo1ss macrumors 68030

    Jun 2, 2010
    Please tell me this is a joke post by someone who picked up a few buzz words along the way. Measuring Farads and Henrys you have got to be joking LOL.
  8. SilverD, Jan 14, 2015
    Last edited: Jan 14, 2015

    SilverD thread starter macrumors newbie

    Jan 13, 2015
    Thank you lol.
    I read that and thought, wow, electronic servicing techniques have changed since the last time I was in the trade! I used to have a meter for measuring ESR of electrolytic caps but I've never found the need to measure farads. And inductors are surely only ever open circuit if faulty (or to be sure, check the output with a scope).

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