Macbook A1466 820-3437-A no green light and fan speed full

[Paul20]

Hi guys
The PC in question starts automatically when the power supply is connected both with magsafe power supply and with bench power supply it behaves the same.
This happens both when the pc is whole, i.e. with all the periferals connected, and only with the card removed from the case bare and raw.
There is no light on the magsafe connector, the fan spins fast and nothing appears on the screen.
I understand that the main voltages are present on the board, if I have checked correctly.
PP15V_TBT is not present.
There is no obvious oxide damage or the like, or anything like that.
It seems to me that I only noticed a sort of small hole on the Q5820, I am attaching the photos (apologies if they are not crystal clear) TBT Sensor.
Could that be the cause? What can I check?
I gladly accept advice.

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

No green / orange light means you do not have the PP3V42_G3H power rail which is used to power the single wire communication of the magsafe interface (head only for your case). This single wire communication is used to soft start a true Liteon (Apple original) power supply and is also used to index the green / orange LED inside the magsafe head.

Select your meter to DC 20v or higher voltage scale.

Measure the voltage to ground of each point (with your power adapter connected) of:

D7005, pin # 1; Red probe on this pin; black to ground
D7005, pin # 2
D7005, pin # 3

Then check the voltage to ground of PP3V42_G3H @ L7095.

Post each measurement.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Here are the voltages:

D7005 pin n. 1 - 8.12V

D7005 pin n. 2 - 14.66V

D7005 pin n. 3 - 14.39V

L7095 PP3V42_G3H - 3.40V

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

What is the voltage to ground of ppbus_g3h?

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

ppbus_g3h - 8.11V

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Review the first case here:

https://repair.wiki/index.php?title=...e_view_desktop

Linked to the SMC unable to communicate with the ISL to boost this ppbus_g3h voltage.

Do check the voltage to ground of the smbus SDA and SCL lines on the isl part.

High fan speed = faulty sensor readings = faulty smbus communication.

[reformatt]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Most common problem is SMC is stuck in reset (SMC_RESET_L is stuck low). Usually corrosion around U5110 or J6100. Also check for presence of PP3V3_S5_AVREF_SMC

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Review the first case here:

https://repair.wiki/index.php?title=...e_view_desktop

Linked to the SMC unable to communicate with the ISL to boost this ppbus_g3h voltage.

Do check the voltage to ground of the smbus SDA and SCL lines on the isl part.

High fan speed = faulty sensor readings = faulty smbus communication.

Smbus SDA and SCL lines on the ISL part - 3.39V

Other measurements:

PPBUS_G3H - 8.12V

It's low because from how I understand it it should be 8.55V
(as from Louis Rossmann's video)

L7095 on pin 1- 2.85V pin 2 - 3.41V

Also from Louis' video, I saw that on pin 1 of L7095 I should have 3.42

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Most common problem is SMC is stuck in reset (SMC_RESET_L is stuck low). Usually corrosion around U5110 or J6100. Also check for presence of PP3V3_S5_AVREF_SMC

Around U5110 and J6100 there are no signs of corrosion.

I noticed a sign of corrosion near U5000 and exactly on pin 1 of C5125 (PP3V3_S5_AVREF_SMC that you asked to check)
There is 3.28V at this same point

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

L7095 pp3v42_g3h - 3.40v

Your reading is very close but remove all power. Measure the resistance to ground of the same L7095 inductor.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Your reading is very close but remove all power. Measure the resistance to ground of the same L7095 inductor.

Red probe diode mode at ground if I understand correctly
0.330

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Your reading is very close but remove all power. Measure the resistance to ground of the same L7095 inductor.

Red probe diode mode at ground if I understand correctly
0.330

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

We are after the resistance check so meter in resistance mode.

One probe (any color) to L7095. Other probe to ground. Resistance will be in ohms.

If you see '1' or 'OL' then the meter scale is too low so switch to a higher scale.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Ok sorry for the misunderstanding.
488 kohm

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Resistance is ok, although is futile (Star Trek).

Voltage is ok.

Measure the voltage to ground of SMC_RESET_L signal.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

resistance is ok, although is futile (star trek).

Voltage is ok.

Measure the voltage to ground of smc_reset_l signal.

3.05v

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

SMC is not stuck low.

Measure the voltage to ground of PP3V3_S5_AVREF_SMC.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Around U5110 and J6100 there are no signs of corrosion.

I noticed a sign of corrosion near U5000 and exactly on pin 1 of C5125 (PP3V3_S5_AVREF_SMC that you asked to check)
There is 3.28V at this same point

This I had already explained this in the post #9

PP3V3_S5_AVREF_SMC - 3,28V

[mon2]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Can you post a pic of the area with corrosion ?

U5000 (SMC) may need to be fluxed and reflowed.

[Paul20]

Re: Macbook A1466 820-3437-A no green light and fan speed full

Can you post a pic of the area with corrosion ?

U5000 (SMC) may need to be fluxed and reflowed.

So should I try a reflow on U5000?
There is resin in the corners holding it in place.