A1278 820-3115 stuck in sleep mode

[guruji]

Hello all
I have a a1278 820-3115 first no power I changed the smc no I have the fan spin all voltage present even get cpu core 1.1v but no chime no display. I programmed. The bios same problem I notice 2 things the system led is solid and the the spi rom pin 5 and 6 have no voltages in on state. But if I power down the laptop then I see all voltages on the spi rom. Also plt_rst_l i3.3v and buffer side 1.05v.I have changed 3 smc and now the intel hm77 chip also still same problem
What signals to check.lid switch also okay without ram should give us beeps

Thanks

[mon2]

Re: A1278 820-3115 stuck in sleep mode

What is the exact voltage of PPBUS_G3H ? You can measure @ F7040.

[guruji]

Re: A1278 820-3115 stuck in sleep mode

12.5v ppbus

[mon2]

Re: A1278 820-3115 stuck in sleep mode

What is the voltage of SMC_PM_G2_EN ?

Voltage of PP5V_S3_AUDIO ? (known bad area for cap faults)

[guruji]

Re: A1278 820-3115 stuck in sleep mode

So
I get all voltage rails 5v 3.3v 1v 1.5v 1.8v and cpu core is 1.12v
Cpu_agx missing no voltage.all_sys pwrgd also 3.3v I get clocks also 25mhz
So this is strange the fan is full speed and on the oscilloscope is see no spi bios communication what is strange when the board is on spi bios chip 5 & 6 have no voltage at all but if I shutdown them pin 5&6 have 3.3v .even plt_rst buffer is 3.3v which goes to a buffer 74lvc1g07 and outputs 1.05v
So what am I missing now here
Thanks

[mon2]

Re: A1278 820-3115 stuck in sleep mode

Can you post the requested voltages ?

[Sergio Kub]

Good afternoon,
I'm repairing a board similar to this one and with the same symptom:
Turns on, but stays in sleep with the light on.
I took these voltage measurements and PPBUS_G3H 12.61V - SMC_PM_G2_EN 3.3V - PP5V_S3_AUDIO 5V - all_sys pwrgd = 3.3V

[Sergio Kub]

Re: A1278 820-3115 stuck in sleep mode

Can you post the requested voltages ?

Can you help me ?

[mon2]

Measure the voltage to ground of each pin on the battery connector. Interested in the SMBUS SCL and SDA voltage measurements. The same SMBUS interface is used to configure the PPBUS_G3H voltage by the SMC. My bad - I think you are ok on PPBUS_G3H and the voltage is ~12v6 after boosting.

Try a new reflashed bios. Can post some if needed.

[Sergio Kub]

J6950
1, 2, 3 GND 0V
4 - 3.456V
5 - 0V
6 - 3.456V
7, 8, 9 - 12.08V
* Measurements with the battery plugged in

[Sergio Kub]

This Mac was showing this defect, I turned the J6955 off and on again and it started working again.
Now it stopped again and went into hibernation.

[Sergio Kub]

I cleaned it with isopropyl alcohol and re-soldered the board in the area of the Bil Connector (J6955) and it was fine. Thank you very much !

[mon2]

Well done!!

[Sergio Kub]

It came back with the same defect. How bad

[Sergio Kub]

@mon2
Can you help me with this defect. I took several measurements and compared them and everything seems to be ok. Sleep light is on, stuck.

[mon2]

Check the voltage to ground of the attached. This signal is from the lid sensor that is working with the trackpad.

[Sergio Kub]

Voltage to ground 3.125V on both sides of R6961 and C6951 3.47V

[mon2]

Close the lid and check the same points.

[Sergio Kub]

Closed the lid Pin5-C6955=0V Pin3-C6951=3.125V

[Sergio Kub]

I noticed that when I close the lid, without the bil connector connected, the standby light goes off.