820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

[KappaDev]

Hi I have a 820-00165 with a known good and working DC-In board, currently that is the only thing connected to the board. No green light on charger.

PPDCIN_G3H = 15.04V
PPDCIN_G3H_ISOL = 15V
PPBUS_G3H = Moves around between 0.6V and 1.4V in no specific pattern (Measured on both sides of F7140)

PPBUS_G3H resistance to GND measures OL

PPBUS_G3H seems too low. Any ideas?
Boardview and schematic attached.

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Hi. See attached.

1) Remove fuse F7140.

2) Power up without the fuse F7140 and check the voltage of PPBUS_G3H @ F7140, pad # 1. This will be the output of this regulator before the fuse (L7130, pin # 2).

What is the voltage without any load on PPBUS_G3H ?

3) Next, check the voltages at the points referenced by the arrows. Post the measurements.

[paulyboy]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

you wont have correct ppbus if your missing pp3v42, make sure you have that first.

once that is sorted move on to ppbus g3h

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

No green light on charger.

This means that you do not have PP3V42_G3H. The PP3V42_G3H rail is required to power the single wire communication that turns the LED inside the magsafe head GREEN / ORANGE.

You may not have PP3V42_G3H if Q7010 is OFF.

Q7010 will be off if the voltage @ R7010 / R7011 junction is not ~6v8.

Confirm the voltage at:

a) Q7010, pin # 1 (drain) = PPDCIN_G3H_ISOL

b) R7010 & R7011 junction

c) Q7010, pin # 4 = GATE

[KappaDev]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Hi. See attached.

1) Remove fuse F7140.

2) Power up without the fuse F7140 and check the voltage of PPBUS_G3H @ F7140, pad # 1. This will be the output of this regulator before the fuse (L7130, pin # 2).

What is the voltage without any load on PPBUS_G3H ?

3) Next, check the voltages at the points referenced by the arrows. Post the measurements.

Without F7140 I consistently get green and then orange light on charger. Both sides of fuse >10MOhm so doesn't appear to be shorted directly.

Voltage on pin 1 of F7140: 8.58V
Pin 1 of R7006: 0.7V
Pin 1 of R7005: 15.08V
Pin 3 of D7005: 14.68V

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Good readings.

Something is not making sense here - without the fuse, the PPBUS_G3H is in the normal range. With the fuse, the PPBUS_G3H tanks to a very low voltage yet the fuse does not blow. Also, the fuse, pin # 2 (aka downstream / consumer / load side) does not have a short?

Can you confirm the meter scale used for the resistance checks for pin # 2 of the fuse F7140 ? Perhaps take a picture if possible?

For resistance checks - NO POWER to the logic board.

Is it possible that the meter is showing OL (over limit) -> then switch to a higher meter scale to measure. This is only to confirm that there is indeed not a low resistance reading on the downstream / consumer side of the logic board.

If the above are not at fault, place your meter in DC volts mode.

Measure the voltage @ pin # 28 (CSIP) to ground of U7100 (ISL6259). Reading ?

Repeat with checking the voltage @ pin # 27 (CSIN) to ground of U7100 (ISL6259). Reading ?

Next, remove all power. Meter in resistance mode -> lowest scale.

Measure the resistance from pin #28 (U7100) to R7120 (pin 2/4). Reading?
Measure the resistance from pin #27 (U7100) to R7120 (pin 1/3). Reading?

We are confirming if the current loop for the PPBUS_G3H rail used by U7100 is in tact.

[KappaDev]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

We are confirming if the current loop for the PPBUS_G3H rail used by U7100 is in tact.

Thank you for your reply! I appreciate the help on this
I agree it is very odd. And with the fuse replaced if I unplug and replug the charger a good 40 times eventually it will get green light and fan spin.
Otherwise no light and the aforementioned results. To rule it out, I am using a genuine known-good charger as well.

(The following measurements are still without fuse)

in the MOhm range, 20MOhm and rising on pin 2 of that fuse.

With Power:
voltage @ pin # 28 (CSIP): 14.53V
voltage @ pin # 27 (CSIN): 14.53V

Without Power:
resistance from pin #28 (U7100) to R7120 (pin 2): 10.4Ohm
resistance from pin #28 (U7100) to R7120 (pin 4): 10.6Ohm
Measure the resistance from pin #27 (U7100) to R7120 (pin 1): 10.4Ohm
Measure the resistance from pin #27 (U7100) to R7120 (pin 3): 10.4Ohm

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Above look ok. Remove all power. Meter in lowest resistance scale.

Check the resistance to ground of the following:

PP1V05_S0 (can be @ C7649, pin # 1)

PPBUS_S5_HS_COMPUTING_ISNS (can be @ C7620, pin # 1) - Louis' forum stated that they had a defective C7620 that caused the same set of events)

What may be happening here is that PPBUS_G3H is split downstream to power other lower voltage power rails. Each has a local current sense circuit. If for some reason the local current sensor is tripping then this is causing the fault.

[KappaDev]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Above look ok. Remove all power. Meter in lowest resistance scale.

Check the resistance to ground of the following:

PP1V05_S0 (can be @ C7649, pin # 1)

PPBUS_S5_HS_COMPUTING_ISNS (can be @ C7620, pin # 1) - Louis' forum stated that they had a defective C7620 that caused the same set of events)

What may be happening here is that PPBUS_G3H is split downstream to power other lower voltage power rails. Each has a local current sense circuit. If for some reason the local current sensor is tripping then this is causing the fault.

PP1V05_S0 (C7649, pin # 1): 285 Ohm
PPBUS_S5_HS_COMPUTING_ISNS (C7620, pin # 1): 4.5MOhm

Funny enough, I do see an odd tiny black dot on the top side of C7620. Let me try swapping that and report back!

[KappaDev]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Funny enough, I do see an odd tiny black dot on the top side of C7620. Let me try swapping that and report back!

Darn, I thought that was the key as after replacing that cap it did boot about 5 times with fuse (maybe board being warm?)
Then eventually same condition as before

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Booted normally the 5 times and you saw video ?

Remove the SSD and boot again.

Remove all power -> meter in lowest resistance scale -> check the resistance across this fuse (F7140).

[KappaDev]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Booted normally the 5 times and you saw video ?

Remove the SSD and boot again.

Remove all power -> meter in lowest resistance scale -> check the resistance across this fuse (F7140).

Correct, saw video.

F7140: 0.02Ohm

[mon2]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Remove the SSD and also the trackpad cable and attempt to power up again.

The logic board has pads you can use with tweezers to power up the logic board.

See here for your logic board:

https://beetstech.com/blog/macbook-air-power-pads

The shorting with tweezers will mimic the ON/OFF action from your removed keyboard.

Remove / disconnect the battery if it is connected.

When the logic board fails to boot -> check the voltage on:

pin # 1 of Q7130 (used for PPBUS_G3H) -> reading ?
pin # 8 of Q7130 (used for PPBUS_G3H) -> reading ?

[kingskie]

Re: 820-00165 Low Voltage on PPBUS_G3H, No Green Light, No Power

Remove the SSD and also the trackpad cable and attempt to power up again.

The logic board has pads you can use with tweezers to power up the logic board.

See here for your logic board:

https://beetstech.com/blog/macbook-air-power-pads

The shorting with tweezers will mimic the ON/OFF action from your removed keyboard.

Remove / disconnect the battery if it is connected.

When the logic board fails to boot -> check the voltage on:

pin # 1 of Q7130 (used for PPBUS_G3H) -> reading ?
pin # 8 of Q7130 (used for PPBUS_G3H) -> reading ?

sorry i replied to wrong thread