Macbook A2141 820-01700 PPBUS Partial Short

[Instafixx]

Fuse Removed. PPBUS is .120 diode mode. PPBVAT is .540

Checking all Big Coils.
L7660 is 0.002
L8102 is 0.112
LA710/20/30/40 is 0.002
LA870/60 is 0.04
LA950 is 0.04
L7410/20 is 0.009
L7211/21/31 is 0.003
La750 is 0.005
LA850 is 0.06
L9580/81 is 0.122

Rest all are higher reading above 300-400 hence didnt post.

Removed U9580. PPBUS short is gone.
L9580/L9581 is still 0.122
SSD gone?

 

[2informaticos]

Some damage has been done in that SSD area.
PPBUS_G3H went to NAND and you should remove and see if low value disappear.

 

[Instafixx]

What should i remove ?

 

[2informaticos]

The NAND chips...

 

[Instafixx]

okay. but even if removing nand chips solves the low value issue. SSD failure repair are tough and expensive

 

[Instafixx]

U9300 was culprit.

I was doing the NAND Programming via JC P13 and i have a question.
The NAND List on Logi.Wiki shows that the 6 NAND Chips are 192gb each.
But the programmer reads it as 128gb.
Also i have a the same Toshiba Nand Chip from an iPhone of 128 and 256gbs. Can those be programmed and used?

 

[2informaticos]

The schematic has BOM tables.

You can try the NAND from iPhone, if has the exact marking code.

 

[Instafixx]

It has the same exact model code but a different GB. I have ordered a NAND Chip. It was like 25 USD. I hope i am able to pull this off.

 

[Instafixx]

Hi,
I replaced the shorted NAND. Programmed all of the NANDs via the JC Programmer and put them back at the exact same position.
Also replaced U9580.
Still no voltage at PP2v5 and PPBUS.

PPDCIN is 5V. PPBUS is 0V.

Was checking around U7000.
R7022 is 0.3 Ohms
R7021/61/62 is 1.3 Ohms

 

[2informaticos]

PPBUS_G3H is the first voltage to appear on the baord.

Remove F7000/1 and check C7050 voltage.

 

[Instafixx]

Even with Fuse removed. PPBUS and C7050 is 0V

 

[2informaticos]

Did you removed both fuses?
Check diode mode to ground at C7050.

 

[Instafixx]

okay i dont know what happened but my PPBUS_G3H is now shorted. Diode Mode to Ground 0.038
L9080 and L9580 are normal diode mode readings of 0.380 to 0.400.

Should we inject 1V?

 

[Instafixx]

U6520 was shorted. Replaced. Short is gone.
PPBUS_G3H is now 0.425
With Both Fuses Removed.
Voltage at C7050 is 12.28V

But when i connect the Fuses.
Amp Meter Reboots. Voltage at the Fuse goes upto 3V and cycles.

 

[2informaticos]

"PPBUS_G3H is now 0.425"
Did you check it on output pin of fuses?

 

[Instafixx]

Put back the Fuses. Getting 12.3V now stable. But no Voltage at the SSD Power Rails. Did we mess up the SSD repair or DFU is still worth trying.
I am getting 12.3V at C9073 and C9080. Something after that isnt letting the voiltage go to the SSD rails

 

[2informaticos]

Many times SSD voltages appear after DFU restore.
Try first DFU revive; this will not erase SSD.

 

[Instafixx]

Machine not entering DFU via keyboard method.

PP1v8_SLPS2R is also 0.03V

 

[2informaticos]

Can't enter DFU without 1V8_SLPS2R.

What about other coils near U7800?
Where no voltage present, check in diode mode to ground.

 

[Instafixx]

L7811 and L7810 didoe mode reading is 0.002. Didnt Check further.
U7800 bad ?