Will not power up, a MOSFET get's instantly hot, possible to replace?

When I connect the charger to the Mid-2009 15 inch MacBook Pro logic board, I noticed one (or both) MOSFETs gets very hot instantly. However, they don't get so hot that it's visibly burnt. They are located near the battery connector (and SODIMM clips). I feel this is likely the problem to why the MacBook will not start up.

With a carefully taken photo, I determined a black imprint of "K0305 9F2 520X" on both neighboring MOSFETs. (I will post close up photo and a photo of the whole board when I find a place I can upload it.)

I have included the photos below now. The logic board number is 820-2523-B.

Is it possible to replace these chips? I do have minimal experience with soldering small surface mounted chips and fuses. I have been able to Google MOSFET K0305, but beyond that, the other numbers are all different. What would be a comparable MOSFET. What do each of the three numbers indicate?

Has anyone attempted or had success with this fix?

Any input would be very welcome!

Thanks,

Tom

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gatortpk, that is reference designator Q7030 which is a RJK0305DPB MOSFET N-CH 30V 30A LFPAK It is available at places like this. It is part of your PBus Supply & Battery Charger circuitry. Hope this helps, good luck.

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Thank you so much oldturkey! I'm genuinely impressed with your answer. Thanks for the info and the link. I'll order a few of those MOSFETs, and then practice soldering them on an older fried MBP board I have laying around, before attempting to fix this (still nice) MacBookPro.

(It seems like the specs 30A 30V would refer to 900 watts total!? Doesn't seem likely those are actual simultaneous limits. I suppose it's 30 Amps OR 30 Volts limits?)

Thanks again,

Tom

I've ordered 10 of those MOSFET N-CH 30V 30A LFPAK (RJK0305DPB-00#J0CT-ND). Is it possible that some other bad boards I have, have this exact same problem (though I haven't seen burnt marks there either)? How common is this PBus Supply failure?

Thanks again,

Tom

First off, thank you for accepting my answer. Over the last few weeks I noticed an increase in that particular FET showing up as issues. Since it is part of the main power supply and battery charge circuitry, I suppose it also take a lot of power surges etc. You can most certainly check your other boards, lets face the components are not to expensive and it is a great learning experience. As you noticed on the datasheet, max power is 45W so the drain voltage is max to receive by the FET and 30A would be quite a jot on the rest of the circuitry...;-)

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