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msh

macrumors 6502
Original poster
Jun 13, 2009
356
128
SoCal
Machine suddenly shutoff and now won't power on.

Followed steps in tech manual; red LEDs flash when power connected and STBY yellow LED lights when diagnostic button pushed. Nevertheless, I replaced the power supply and it did power up and boot normally and stayed on for about 8 hours before I did a manual normal shutdown. Restarted the next morning normally then another abrupt unattended shutdown while idle after about an hour. Now won't start at all.

I have taken it down to almost (everything except removing the CPU from its socket) a minimal configuration per the manual and still can't start it even from the jumper pads on the back plane. So it must be the backplane or the CPU tray, right? I am guessing the backplane board as I remember Apple replacing that during the 4th year of ownership.

Is it worth replacing the backplane in this thing or just getting a used 2010 for about $500? Will the 4,1 2 x 16gb 1066mhz dimms work in a 2010? It is a pity to trash this machine as the chassis alone is such a beautiful and well made thing.
 

MIKX

macrumors 68000
Dec 16, 2004
1,815
691
Japan
I recently had the same problem .. . but after removing and thoroughly de-dusting the PSU I got CPU A working.

Did you check the Northbridge heatsink retainer spring rivets on the CPU tray? They break with surprising frequency.

replacing them and re-newing thermal paste has fixed quite a few cMPs.

In the end it seems it was a CPU socket problem. I ended up getting a refurbished CPU tray with 32gb ECC RAM.
works like a charm now.

Probably just old age.
 

msh

macrumors 6502
Original poster
Jun 13, 2009
356
128
SoCal
I recently had the same problem .. . but after removing and thoroughly de-dusting the PSU I got CPU A working.

Did you check the Northbridge heatsink retainer spring rivets on the CPU tray? They break with surprising frequency.

replacing them and re-newing thermal paste has fixed quite a few cMPs.

In the end it seems it was a CPU socket problem. I ended up getting a refurbished CPU tray with 32gb ECC RAM.
works like a charm now.

Probably just old age.
That I haven’t tried. Thanks for the suggestions. I will probably take it to a repair shop.
 

msh

macrumors 6502
Original poster
Jun 13, 2009
356
128
SoCal
It was the logic board (backplane). But I will keep in mind the heat sink rivets and new paste for the cpu.
 
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