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Sell me your broken computer

Penryn Macbook 2.4 Ghz won't turn on

edited November 2011 in MacBook
Hey John

Thought I would start a new thread. This is another laptop that I am currently working on for a classmate. Alright, same story, he spilled liquid on the computer keyboard. So I got the laptop, plugged it in, got a solid green light at first...so I was a happy at first because on the last liquid damage MB that I worked on it was a feint green...anyway, I pushed the power button and got a lil flash of light on the LCD screen and then nothing...no fan turned over, just absolutely nothing. It doesn't even sound like a computer. I do have a white light on the bottom left of the keyboard, the "sleep" light i think it is called.

Anyway, I am going to take it apart and look, but what are your first thoughts? Just a new motherboard? Or, could it be worse?

Thanks

-Taylor

Answers

  • Reset PRAM and PMU/SMC, but the first thing that comes to mind is a bad RAM slot. Pull one of the two modules and power on, and then if that doesn't do anything, put RAM in the empty slot and pull the other module. Lots of these machines have one bad RAM slot, and they behave like you describe when there is memory in the bad slot. As long as the bad slot is empty, the machine works fine.

    Beyond that, I'd open the machine up and clean off corrosion with 90% alcohol.
  • Alright, so, I opened it up and took the motherboard out. I have to say, the motherboard looked really good other than dust and I saw a tiny bit of corrosion right under the power pads on the motherboard (820-2279A). I cleaned the whole motherboard last night with 90% alcohol and q-tips. Now, I have a spare motherboard (820-2279A) that dies as soon as it hits the OS. I plopped that in and I was able to actually get something on the screen. I got the all white with the apple logo. So now I know its not the screen/inverter, none of that.

    After everything dries, I am going to put in the original motherboard and see what happens. I will also take one memory card out and boot and then switch them. I will also try to reset the PRAM and PMU/SMC.

    Am I doing anything wrong? How am I tackling this thus far?

    Thanks as always.

    -Taylor
  • edited December 2011
    It's hard to say -- did you do the resets I mentioned, test the RAM slots, etc.? It would have made more sense to do all of this first. If the problem is just that the brightness is all the way down (fixable via a PRAM reset) or that there is a bad RAM slot, you might have done a ton of extra work for nothing, and you might not need to have cleaned the board, or even gone into the machine. Even when cleaning the board, it's not usually necessary to take it all the way out, or clean parts of it that don't show corrosion, because you might cause additional damage to board components (i.e. if it's not broken, don't fix it). It's important to have a logical, systematic, step-by-step approach, and take note of what you learn from every step and react accordingly...otherwise the situation will get confusing and you'll end up with a pile of parts that you haven't learned anything about.

    Also, if you do too many things at once, you won't know which of those things ended up making a difference. You cleaned the board, but what specific problem was it you were trying to solve by doing that? Every step you take should be a calculated response to as specific a problem as you can manage to define. But if the problem itself has not been clearly defined (by doing the steps I list above), then you are implementing a non-specific resolution to a non-specific problem, and that's only asking for things to get really messy really fast.
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