820-3462 not turning on

[mushr00m]

its not turning on

I dissemble everything and now I am with the bare board and the DC-IN adapter


PP18V5_DCIN_FUSE = 17V
PPBUS = 0V F9700
PP3V42_G3H = 0V

 

[2informaticos]

Post Q6910 voltages.

 

[mushr00m]

pin 5 and pin 4 are both 16.85V

the others are all 0

 

[2informaticos]

Check D6910; seems to be open.

 

[mushr00m]

Probably when dissamblying I removed it

Put another one back and now we have it

PPBUS = 12.26V F9700
PP3V42_G3H = 3.4v
PP5V_S4 = 0
PP5V_S3 = 0
PP5V_S0 = 0
PP3V3_S5 = 0

 

[2informaticos]

Post U7000 basic voltages: 1, 2, 3, 9, 12, 13, 14, 15, 17, 19, 20, 27.

Check diode mode and voltage at SCL/SDA lines of battery bus.

 

[mushr00m]

1 0
2 16.8
3 4V
9 0
12 3.4
13 3.41
14 3.20 then drops to 3.16 and goes up to 3.20 in a loop not sure if its normal behavior
15 0
17 12.26
19 5.45
20 5.46
27. 16.56


SCL/SDA
Is it PIN 10 and 11 on U7000?
SMBUS_CHGR_SCL AND _SDA? If it's

VOLTAGE
SDA 3.4V
SDL 3.4V

DIODE
SDA 0.495
SDL 0.495

 

[2informaticos]

SMC_RESET_L comes high?

 

[mushr00m]

SMC_RESET_L = 3.36v

 

[2informaticos]

Check other SMC signals and voltages; page 39, U4900 (2 OF 2).
If all good, change SMC...

 

[mushr00m]

I will measure.

However do you think it could be bad SMC?

Is it possible to reball it and clean the area and put back?

I am used to do that on A1278 models and it worked when it was some bad connections or oxidation below the SMC.

Does that make sense for a situation like this?

 

[2informaticos]

Nothing to lose with reballing; apart of time, of course.

 

[mushr00m]

Just reballed it and put back

The area around it was dirty a bit and I cleaned some of the SMC pads and put it back

Still no green light

Where should I go?

 

[2informaticos]

You probably need to replace SMC.

"I will measure"
???

 

[mushr00m]

Replaced the SMC with another one with the same schematic description from a board 820-00165

Now the machine is turning on.. I do have greenlight

HOWEVER its really SLUGGISH

and If I try to turn on only using the battery without the magsafe connected it goes to login and starts loading the system and the crashs and restar in an infinite loop

Already did RESET SMC, RESET PRAM

Fan is at full speed

Also important to mention that CUSTOMER HIMSELF replaced the battery but it charged good until 100%

 

[2informaticos]

You need to get SMC from donor board, EXACT same model.

Just in case, check if SMCTool has an option to reflash it.

GitHub - MuertoGB/SMCTool: 💻 SMCTool is used to program LM4F SMC firmware on Mac devices made between 2013-2017 in EFI mode.

💻 SMCTool is used to program LM4F SMC firmware on Mac devices made between 2013-2017 in EFI mode. - MuertoGB/SMCTool

github.com

 

[mushr00m]

Since I do not have a exact same model donor board.

I am thinking to go with this SMCTool.

I think I able to create the USB stick with the tool

But since its a board with a NAND. I will not be able to remove the HD/SSD from it. Is there an issue doing it that way?

How about specific flash for 3462? Does it come with the app? I didn't understand this part.

If you can help me fix with this SMC... it would save a lot of time and money

 

[2informaticos]

???

a1425 ssd - Buscar con Google

What's this then?

Choose USB pendrive in boot menu; you don't even need to disconnect SSD (J4500).
Then check if your board is listed in the app.

 

[mushr00m]

Hello

I am creating the USB stick right now.

However there is no 3462 file for the SMC



Also if you go to the SMCTool website

There is this warning.


Not sure If I can find it anywhere else

 

[2informaticos]

Find a scrap 3462 board and take out the SMC...