Macbook 820-00923

[mon2]

Re: Macbook 820-00923

Measure the diode mode reading of PP3V0_G3H.

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[Instafixx]

Re: Macbook 820-00923

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Pin #1 on C1227 its 1.8M (Omega Sign)
Voltage is at 3V too.

I think this line is fine too.

Maybe the U7800 is defective. What do you feel Mon2 ?

[Instafixx]

Re: Macbook 820-00923

What should be done?

[mon2]

Re: Macbook 820-00923

Remove all power. Meter in the lowest resistance scale.

What is the resistance to ground of PPVCC_S0_CPU ?

Meter in voltage mode. Measure the voltage to ground of:

PPBUS_HS_CPU (U7210 / U7220 / U7270)
CPUCORE_PWM1
CPUCORE_PWM2
CPUSA_PWM

PPVIN_S0_CPUVR_VIN (U7100)
PP5V_COREVR_VCC (U7100)


Going back to PP5V_S4, can you measure the voltage to ground @ L7600 (pin #1) ?

Do you see a voltage on the working board for this rail ?

Then check the non-working board as well.

This voltage is required to power U7100 (pin # 42) which in turn sequences the CPU voltage phases.

[Instafixx]

Re: Macbook 820-00923

Remove all power. Meter in the lowest resistance scale.

What is the resistance to ground of PPVCC_S0_CPU ?

Meter in voltage mode. Measure the voltage to ground of:

PPBUS_HS_CPU (U7210 / U7220 / U7270)
CPUCORE_PWM1
CPUCORE_PWM2
CPUSA_PWM

PPVIN_S0_CPUVR_VIN (U7100)
PP5V_COREVR_VCC (U7100)


Going back to PP5V_S4, can you measure the voltage to ground @ L7600 (pin #1) ?

Do you see a voltage on the working board for this rail ?

Then check the non-working board as well.

This voltage is required to power U7100 (pin # 42) which in turn sequences the CPU voltage phases.

PPVCC_S0_CPU resistance is 5.5 (Meter kept on the Lowest Scale - at 200.)

PPBUS_HS_CPU is at 13V
CPUCORE_PWM1 is 0.5 Volts


CPUCORE_PWM2 is at 0.5 Volts


CPUSA_PWM is at 0.48 Volts



PPVIN_S0_CPUVR_VIN is 13V


PP5V_COREVR_VCC is at 5 Volts


PP5V_S4 is at 5 Volts.

What can be the issue? i am so utterly confused here!

[mon2]

Re: Macbook 820-00923

Are these measurements from the non-working board?

Compare these readings with the working board.

Do you have caps key light toggle?

External type c to hdmi produce video?

Test for usb activity on each usb port. See if a thumb drive led flickers on each port.

[Instafixx]

Re: Macbook 820-00923

PPVCC_S0_CPU resistance is 5.5 (Meter kept on the Lowest Scale - at 200.)

PPBUS_HS_CPU is at 13V
CPUCORE_PWM1 is 0.5 Volts


CPUCORE_PWM2 is at 0.5 Volts


CPUSA_PWM is at 0.48 Volts



PPVIN_S0_CPUVR_VIN is 13V


PP5V_COREVR_VCC is at 5 Volts


PP5V_S4 is at 5 Volts.

What can be the issue? i am so utterly confused here!

Readings on the Working Board

PPVCC_S0_CPU resistance is 7 (Meter kept on the Lowest Scale - at 200.)

PPBUS_HS_CPU is at 13V
CPUCORE_PWM1 is 0.2 Volts


CPUCORE_PWM2 is at 2.5 Volts


CPUSA_PWM is at 0.21 Volts



PPVIN_S0_CPUVR_VIN is 13V


PP5V_COREVR_VCC is at 5 Volts


PP5V_S4 is at 5 Volts.

Updating the rest in 10 Mins

[Instafixx]

Re: Macbook 820-00923

Are these measurements from the non-working board?

Compare these readings with the working board.

Do you have caps key light toggle?

External type c to hdmi produce video?

Test for usb activity on each usb port. See if a thumb drive led flickers on each port.

Dont have Caps Key Light.
The Power Button is Working.
Pressing it Switches off the Machine (the trackpad doesnt press) and then again switches on using the power Button.

There is no external display with and without the LCD connected.

We dont have any usb to check usb activity .

[mon2]

Re: Macbook 820-00923

Locate for testing a usb c to hdmi dongle or hub that is compatible with macbooks. Test again on both units.

[Instafixx]

Re: Macbook 820-00923

Locate for testing a usb c to hdmi dongle or hub that is compatible with macbooks. Test again on both units.

i Have a hub that has HDMI. There is no external video output.

[mon2]

Re: Macbook 820-00923

Test it on the working board. Any video?

[Instafixx]

Re: Macbook 820-00923

Test it on the working board. Any video?

Yes.

This video output is checked after installing both boards on the body with battery connected and booting the machine.
The bad board doent boot. But has fan spin etc.

[mon2]

Re: Macbook 820-00923

What is the voltage to ground of VCC_S0_CPU ?

Measure for a few seconds.

Compare to the working board.

Reference:

https://boards.rossmanngroup.com/thr...of-life.60763/

[Instafixx]

Re: Macbook 820-00923

What is the voltage to ground of VCC_S0_CPU ?

Measure for a few seconds.

Compare to the working board.

Reference:

https://boards.rossmanngroup.com/thr...of-life.60763/

There is nothing a VCC_S0_CPU . Its PVCC_S0_CPU.

Voltage on the Working Board
1.06V the Drops to 0.6V after a few seconds.

Voltage on the Bad Board
1.06V Stable does not increase.



This Voltage was initally 0V.
We did a reball of U7800 and this Voltage was achieved.

[mon2]

Re: Macbook 820-00923

On the hub, can you insert a usb flash drive? Do you see activity on the usb flash drive? Test on the working and non-working boards.

Do you have the tools to reflash the BIOS?

One thought is to remove the good bios on the good board. Keep the good bios aside.

Then take the bios from the non-working board and apply to the working board.

Does the working board continue to work?

This should confirm if the bios is not corrupted.

[Instafixx]

Re: Macbook 820-00923

On the hub, can you insert a usb flash drive? Do you see activity on the usb flash drive? Test on the working and non-working boards.

Do you have the tools to reflash the BIOS?

One thought is to remove the good bios on the good board. Keep the good bios aside.

Then take the bios from the non-working board and apply to the working board.

Does the working board continue to work?

This should confirm if the bios is not corrupted.

I don't have the tools do flash the bios but i can get that arranged locally.
Flashing the BIOS will remove the Data ? ( I have absolutely no idea about this)

[mon2]

Re: Macbook 820-00923

Bios is used to boot up the logic board. It is the first code used to start up the board. Data is on the ssd of this logic board. That is, ssd could be blank but the bios firmware still will offer the power up apple logo. The operating system from the ssd or internet follows afterwards.

It is only an attempt but perhaps the main bios is corrupt. We do not want to alter or risk the known good bios so best to remove and place it aside.

From the resistance, do not think the CPU is dead but not 100% sure.

Do check for usb activity on both boards to gauge the differences.

Wish to be clear that we do not want to erase or write to the flash device.

Only apply the flash from one board to the other.

[mon2]

Re: Macbook 820-00923

Also, compare the voltage to ground of the spi lines used by the flash memory device on both boards. Post your updates.

[Instafixx]

Re: Macbook 820-00923

Bios is used to boot up the logic board. It is the first code used to start up the board. Data is on the ssd of this logic board. That is, ssd could be blank but the bios firmware still will offer the power up apple logo. The operating system from the ssd or internet follows afterwards.

It is only an attempt but perhaps the main bios is corrupt. We do not want to alter or risk the known good bios so best to remove and place it aside.

From the resistance, do not think the CPU is dead but not 100% sure.

Do check for usb activity on both boards to gauge the differences.

Wish to be clear that we do not want to erase or write to the flash device.

Only apply the flash from one board to the other.

Which programmer will you recommend ?

Also the bad board is bad board is drawing more amps than normal. I will tell you the exact voltages tomorrow .

[Instafixx]

Re: Macbook 820-00923

Also, compare the voltage to ground of the spi lines used by the flash memory device on both boards. Post your updates.

Do you mean the SPI ROM Lines?