2.26 or 2.4 GHz / White plastic unibody enclosure

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Intermittent power up - A1342

Hi all,

I have a problem with my Unibody white MacBook. I'd like to know if anyone would be able to help me fix it!

It was involved in a very minor liquid spill - almost nothing - but now it won't power up all the time. I've investigated it as much as I can and am at the end of my knowledge now.

The symptoms are this:

Connecting the Magsafe works properly and charges the battery. On pressing the power button the light on the magsafe changes to green for a few seconds then back to orange (PMU Reset?) 80% of the time nothing else happens. The other 20% of the time on repeated pressing of the power button (sometimes in quick succession - sometimes just a standard press) the unit will power up. Some keys do not function properly but backlight and everything else are fine.

On a *single* press of the power button while running (this happens every time) the unit goes *straight off immediately*

I have shorted out pins 5 and 29 on the keyboard connection and the same lack of regular power up is observed so I don't think there is a power button fault (and also because the power button will switch the unit off 100% of the time as above)

The fact that the PMU/SMC appears to be being reset when pressing the power is significant but I don't know in what way. I initially thought the shift and alt and apple keys might be stuck down but it happens when the keyboard ribbon cable is disconnected too.

It must just be an intermittent connection somewhere and hopefully not too serious as everything 'works' albeit occasionally!

Can anyone give me a shove in the right direction? I am handy with a multimeter and have a reasonably good solder station. Perhaps some fuse/component testing if you'll tell me where to look?

Many thanks

Ryan

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From your description I think that the top case should be replaced (power button seems to be faulty) also I would do a good logic board cleaning when replacing the top case.

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I just repaired this same model with a soda spill. You'd be surprised what gets shorted out in the keyboard. I would replace the top case (trackpad too unless it didn't get damaged) and clean whatever (you didn't specify what was spilled, like coke is corrosive) you can with isopropyl alcohol taking static precautions of course. Definitely dis-assemble to air it out, You can even put the logic in an oven on cookie sheet at it's lowest temp with door open or in a container with a desiccant. No quick or easy way with this model.

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Ryan Maunder will be eternally grateful.
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