Macbook A1466 820-3437

[Instafixx]

Hello,
I have a Macbook A1466 820-3437 which came to me in dead condition. The charger has a proper Green/Orange light PP3v42 is ok.

Getting 8.58V on PPBUS_G3H.

I know that this Macbook exhibits the Fan on/off/on/off/on symptom before a bare boot.
But in my case first the fan spins normally for about 15 seconds , the it stops. Then it starts spinning again and after 15 seconds it goes on a high spin.

While checking the board i noticed that whenever i probe SMC_RESET_L anywhere on the board - the fan stops to spin.

Has anyone experienced something similar or has anyone make out what am i doing wrong ?

[mon2]

Re: Macbook A1466 820-3437

Measure the voltage to ground of CPU_VCCST_PWRGD.

[Instafixx]

Re: Macbook A1466 820-3437

Measure the voltage to ground of CPU_VCCST_PWRGD.

Its 1.05V checked at Pin#2 of R1931

[dellxps15]

Re: Macbook A1466 820-3437

all_sys_pwrgd voltage on u1950 ?
post u1950 volts when fan spinning.

[mon2]

Re: Macbook A1466 820-3437

Voltage to ground of ALL_SYS_PWRGD?

[Instafixx]

Re: Macbook A1466 820-3437

Voltage to ground of ALL_SYS_PWRGD?

Getting a stable 3.3V at U1950.

[mon2]

Re: Macbook A1466 820-3437

Disconnect the trackpad/keyboard cable. Connect the power adapter.

[dellxps15]

Re: Macbook A1466 820-3437

usb activity ? tried with external display ?

[Instafixx]

Re: Macbook A1466 820-3437

Disconnect the trackpad/keyboard cable. Connect the power adapter.

Booting the Bare Board. No peripherals connected.

[mon2]

Re: Macbook A1466 820-3437

Confirm the presence of the pull-up resistor on SMC_RESET_L.

[Instafixx]

Re: Macbook A1466 820-3437

usb activity ? tried with external display ?

No Booting Chime etc. Do you think external display will work?

[Instafixx]

Re: Macbook A1466 820-3437

Confirm the presence of the pull-up resistor on SMC_RESET_L.

Both R5100 and R7100 are present . No short on ground.

[mon2]

Re: Macbook A1466 820-3437

What is the voltage to ground of SMC_RESET_L ?

If your meter probes cause this line to be flaky, something is wrong with this signal line.

[Instafixx]

Re: Macbook A1466 820-3437

What is the voltage to ground of SMC_RESET_L ?

If your meter probes cause this line to be flaky, something is wrong with this signal line.

Getting 3.12V

[mon2]

Re: Macbook A1466 820-3437

The pull-up resistor @ R5100 is to 3v42. Confirm the voltage to ground of the 3v42 rail.

Remove all power -> measure the resistance across R5100.

Update:

Also confirm the voltage to ground of L5001 (both sides)

[Instafixx]

Re: Macbook A1466 820-3437

The pull-up resistor @ R5100 is to 3v42. Confirm the voltage to ground of the 3v42 rail.

Remove all power -> measure the resistance across R5100.

R5100
Voltages
Pin 1 is 3.46V
Pin 2 is 3.17V

Resistances (Meter in 2K Mode. Red to Ground)

Pin 1 has .261
Pin 2 has .464

[mon2]

Re: Macbook A1466 820-3437

The resistor @ R5100 should be ~100k ohms.

Confirm that your meter scale is 100k or higher. Meter probes across R5100 resistor. No power to the board in checking the resistance.

[Instafixx]

Re: Macbook A1466 820-3437

The resistor @ R5100 should be ~100k ohms.

Confirm that your meter scale is 100k or higher. Meter probes across R5100 resistor. No power to the board in checking the resistance.

Checked with Meter Set to 200K Scale.

Pin 1 is 168
Pin 2 is 67

Red to Ground.

[mon2]

Re: Macbook A1466 820-3437

Review and read the posts carefully.

We are not checking the resistance to ground.

Checking the resistance of the component.

Again, meter across the component.

[Instafixx]

Re: Macbook A1466 820-3437

Review and read the posts carefully.

We are not checking the resistance to ground.

Checking the resistance of the component.

Again, meter across the component.

My Apologies. Meter set to 200k

Red on Pin 1
Black on Pin 2

Meter reading is 91.6