Macbook Air 820-3437 Dead: no s5_pwrgd: MISTERY

[phantomEVO]

i'm using by-3200s and at the beginning of the diagnose, i have had 3,3 on batlow

from where should i start to check the flowchart?

p.s. U7501 basic voltages; 23, 22, 12, 13, 29, 21:

8,5 / 3,3 / 3,4 / 0 /0,7 /3,3

[phantomEVO]

all voltages seems fine unitil SyS_one wire (0v) but i have charging light and pp5v_s5 0,7v

smc_reset_l 3,38

[phantomEVO]

pp5v_s5 is not shorted

[phantomEVO]

ok now with another u7501 i have pp3v3_s5




0v on PM_DSW_PWRGD

SMC_S5_PWRGD_VIN 3,3v

S5_PWRGD not present

0v on PP3V3_SUS

0,3v on PM_PWRBTN_L

[mon2]

0,3v on PM_PWRBTN_L

is the keyboard or trackpad cable connected? Disconnect both. They are not required. Your power on/off button is stuck.

with a good working board, you will have fan spin upon attaching the original power adapter. If the original adapter is not used, that can be the root cause.

[phantomEVO]

I have nothing connected to the board

[mon2]

Confirm the resistance to ground of PM_PWRBTN_L.

this line must be 3v3 during a normal state. When turning on by button, this signal should be low and then high when power button is released.

[mon2]

1) Confirm the resistor R1405 is present and is 1k ohms.

2) Confirm the voltage to ground of PP3V3_S5 on the other side of this resistor. Since you now have this rail working @ U7501, it must reach this pull-up resistor.

3) Confirm the voltage to ground of SMC_ONOFF_L.

4) Confirm the voltage to ground of SMC_RESET_L.

[phantomEVO]

PM_PWRBTN_L 10k

r1405 is 1k, 0,330 voltage to ground

SMC_ONOFF_L.0,600

SMC_RESET_L.0,500

[mon2]

r1405 is 1k, 0,330 voltage to ground

SMC_ONOFF_L.0,600

SMC_RESET_L.0,500

How are these voltage to ground measurements taken? These should be with your meter in DC volts mode using a voltage scale of 5 volts or higher. Or are you measuring in DIODE mode?

[phantomEVO]

Diode mode with red probe on ground

[mon2]

😬

0v on PM_DSW_PWRGD
SMC_S5_PWRGD_VIN 3,3v
S5_PWRGD not present
0v on PP3V3_SUS
0,3v on PM_PWRBTN_L

So these measurements were in DC volts mode to start (ie. 3v3) and then you switched to diode mode for the last measurement of 0v3? For each post, you must clarify how the measurements are being taken. Now unable to follow which reading is in diode mode or normal DC volts scale on your meter.

[phantomEVO]

my first check is for voltages: if not present, i search for shorts (beep mode or diode mode)


0v on PM_DSW_PWRGD
SMC_S5_PWRGD_VIN 3,3v
S5_PWRGD not present
0v on PP3V3_SUS
0,3v on PM_PWRBTN_L

ALL THOSE MEASUREMENTS ARE IN DC MODE

I'm understanding ONLY NOW that you don't mean DIODE mode when you say "measure voltage to ground"

so i have 3,3V on on side of r1405, and 0,3v on the other side!

SMC_ONOFF_L. 3,4v

SMC_RESET_L 3,2v

[mon2]

Back up the original and try a fresh bios image for this board.

[phantomEVO]

could you give me a bios link to flash?

[mon2]

Best to make this request in the dedicated bios forum. I do have a number of images for this machine available and can post them if they are needed. But do not have direct experience with the mods that may be required.

Would you have the programming hardware already? If yes, certainly can share a bunch of images but will do it in the BIOS forum. Very curious to learn of your progress with a fresh bios image.

Here to get you going for some experiments (be sure to backup the original flash first!!!!):

https://we.tl/t-1fCP3rS3NJ
* will expire in 7 days from now
* will post in the bios forum as well but there is a size limit so need to split the fileset

[phantomEVO]

Thank you mon2

tomorrow morning I will flash the bios….

but why you think about a software issue?

What do you think instead about S5_PWRGD????

Could it be a problem of u7501?

[mon2]

Confirm the voltages to ground (not diode mode) for the following load switch which is linked to the PP3v3_SUS line. Since it is 0 volts - check if this low current rail is being enabled. If it is being enabled AND the Vin is present, then this load switch is defective.




Confirm the exact voltage to ground (not diode mode) for PP3V3_S5_REG_R @ L7560. This must be a stable 3v3. Provided it is, then pin # 20 of U7501 should be a logic '1' = power good is OK. This logic '1' will be present only if U7501 is working; soldered properly; external 100k pull-up resistor @ R8141 is present; the pull-up voltage of PP3v42_G3H is present on this same resistor. If this external resistor is missing then you will observe little to no voltage on this power good output because the output signal is 'floating' when the output state is OK = high impedance / like an open switch. The external resistor is required to park this floating output signal.

This power good status is not linked to the bios provided the above conditions are being met by U7501. It is quite important that U7501 is properly soldered and without any contact shorts, etc. Flux it well; heat it well and make it swim into the liquid solder.

[phantomEVO]

i have pp3v3_s5 but 0v on pp3v3sus_en

on l7560 i have 3,325 stable

[mon2]

What is the voltage to ground of PM_BATLOW_L ?