[SOLVED]820-00165 no fan spin but has magsafe

nik1981

Member
At C1031 PPVCC_S0_CPU is either 1.7v or 1.8v, I think my multimeter isn't quick enough. No idea where the 3.3 came from.. My bad
 

JohnB8812

New member
Ok if you're for sure getting pulsing on all the power rails, I would try another BIOS just to see if that is the problem. Keep the original, but try a test BIOS from a donor 00165 to see if the machine boots.
 

nik1981

Member
I've never swapped a bios before, I know theres stuff to do to get it to work correctly, but do you mean just straight swap for now just to test for boot?
 

JohnB8812

New member
Yes just for testing swap one over. Keep the original in case that is the problem Duke can help you with fixing the ME Region and serial number and all that stuff.
 

nik1981

Member
I'll swap it back again. I don't understand why I get VCORE boosting twice but no fan spin. What should I look for?
 

nik1981

Member
The U6100 I tried was from a 2015 00165 board and this is a 2017.. would that make any difference? I could always try ordering in a new U6100 with a clean ME just to be sure I suppose.
 

dukefawks

Administrator
Without BIOS chip the board should be constantly power cycling. Was there any liquid damage around the CPU area?
 

nik1981

Member
Nothing obvious near the cpu at all. To be honest, apart from the backlight chip, there wasn’t much anywhere.

Do you mean if remove the bios chip entirely and then connect the MagSafe, it should power cycle constantly?
 

nik1981

Member
Without the bios, its boosting PM_SLP_S4_L and VCORE in stages by the looks of it. So it boosts after every 2 second pause and changes the voltage up or down each time in a cycle.

VCORE = 0.08v (pause) 0.12v (pause) 0.24v (pause) 0.53v (pause) 1.1v (pause) 1.3v (pause) then does the same in reverse
PM_SLP_S4_L = 0.24v (pause) 0.46v (pause) 0.80v (pause) 1.20v (pause) 2.3v (pause) 2.7v (pause) then reverse

It's almost like it doubles the voltage roughly until it gets to the voltage it wants, then reverses and does it all over again.

Is that normal behaviour without a U6100 chip?
 

dukefawks

Administrator
Probably just your meter that is not fast enough to catch the pulses. At this point I am out of ideas, it could be anything including a dead CPU.
 

nik1981

Member
So with the U6100 attached it boosts twice. Without it attached it boosts constantly.

Is that it then? Bin it and replace the board?
 

nik1981

Member
Okay, I've gone back through checking the rails... PP3v3_S4 boosts twice the same as every other S4 onwards rail, but after the others boost twice, they drop to 0v. PP3v3_S4 drops to 0.45v and sits there.

The damage was in the U3210 area, so I swapped out U3210 to see if it made a difference.

I now get PP3v3_S4 and it seems like its on because the CPU is getting hot after a min or so and VCORE is a constant 1.8v

Still no fan spin though.
 

nik1981

Member
Stuck the board in the mac, connected screen etc up and it starts, chimes and displays!! still no fan spin..lol :p
 
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