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Old 09-08-2021, 04:08 PM   #1
marce002
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Default Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Hello

Need just to know how do you guys determine what the problem is, when we have some fluctuating volt, to discard a faulty TPS 51125 , or if the issue is after this IC.

CRAZY JUMPING

PP3V3_S5 = 0v to 3.33 v jumping
PPBUS_G3H = 12.4v to 12.48 jumping a little
PP5V_S5 = 2v to 5v aprox, jumping fast
P3V3S5_ENTRIP = crazy jumping from low volt
SMC_PM_G2_EN = jumping 0v to 3.3v crazy


STEADY


P3V42_G3H=3.39V steady
PP5V1_CHGR_VDD=5.06v steady
PPCHGR_DCIN= 18.29 to 18.31 jumping



thanks for any help in advance, can measure whatever you need and also have a working similar board but 2011.

Apple Macbook Pro 15 A1286 MLB,K18 051-8504 820-2850 WHITE ARROW (02-01-10) Schematics.pdf

Apple Macbook Pro A1286 820-2850-A BoardView.rar
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Old 09-09-2021, 05:59 AM   #2
mon2
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Power down / remove battery.

Meter in resistance mode (200 ohms). Check the resistance to ground on each and every coil on the logic board.

Checking for very low resistance readings for potential shorted caps. The CPU rail is expected to be a low reading - that is normal.
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Old 09-09-2021, 09:02 AM   #3
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

L7330=27kohm
L7530=41.5ohm
L9560=113.2ohm
L8920=2.5ohm (GPU..... I'm aware of this macbooks issues here but this might be ok, who knows)
L7425=132.7ohm
L7415=132ohm
L7630=23.7ohm
L7030=1.99Mohm
L7220=23kohm
L7720=0.234kohm

The Macbook has only green led does not power on, no water damage, unknown history, connected to my bench with magsafe 1 power cord, and cycling from 8mah to 23mah consumption. does not start fans (no battery attached)

thanks mon2

Last edited by marce002; 09-09-2021 at 09:10 AM..
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Old 09-09-2021, 12:02 PM   #4
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Just to test... removed main fuse f7040 and ppbus_g3h is stable as usual.. so not blame u7000.
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Old 09-09-2021, 01:40 PM   #5
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Quote:
Originally Posted by marce002 View Post
L7330=27kohm
L7530=41.5ohm
L9560=113.2ohm
L8920=2.5ohm (GPU..... I'm aware of this macbooks issues here but this might be ok, who knows)
L7425=132.7ohm
L7415=132ohm
L7630=23.7ohm
L7030=1.99Mohm
L7220=23kohm
L7720=0.234kohm

The Macbook has only green led does not power on, no water damage, unknown history, connected to my bench with magsafe 1 power cord, and cycling from 8mah to 23mah consumption. does not start fans (no battery attached)

thanks mon2
What's the resistance to ground of L7260?
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Old 09-09-2021, 03:45 PM   #6
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

sorry i forgot that one because it is under the speaker.... it is

L7260=8.77kohm
L9701=0.400Mohm

Last edited by marce002; 09-09-2021 at 03:49 PM..
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Old 09-09-2021, 04:00 PM   #7
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

My question is: Given that f7040 removed is having steady 12.35v one side, but when i solder back I have a slight variation between 12.4v to 12.48, but all dependant lines have a more crazy variations like PP3V3_S5 = 0v to 3.33 v jumping, the question is how can i isolate the other parts or when to inject volts..red lines in this picture

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Old 09-09-2021, 06:50 PM   #8
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Current sense resistors are ok (the 4 ones) in U7000 area, 10ohm, 0 ohm and 2.2ohm ...
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Old 09-10-2021, 06:37 AM   #9
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

i have been lifting up coils and testing volt /mah variation in my power supply and L7260 was the cause of jumping...when that on removed (one leg) I can see steady output,,,,,, so i will put it back that coil and check what might be wrong in that area, which is the 3,3 and 5v power supply....

SO i think I have somethjing wrong with 3.3v , need to know if load side or ic source side.... the ohms each side of L7260 are: pin 1 lifted = 4.5kohm (red on ground resistance mode) and pin 2 = 11kohm

Last edited by marce002; 09-10-2021 at 06:44 AM..
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Old 09-10-2021, 09:22 AM   #10
marce002
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Default Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

ok it is on!!!!! with chan sound and also image!!!!! after some debugging and heatings to the board while inspecting derived loads from PP3V3_S5.... full speed fans though an quite slow.....

closed
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