[help] 820-01958 dead: 20v not switching

[phantomEVO]

LDO_CORE 1,49
PP0V8_SLPS2R 0v
PP3V_G3H 0v
PP1V2_AWAKE 0v
PMU_LDO3_OUT 1,79v
PP1V1_SLPS2R 0v
PP3V3_G3H 2.4v
PP1V8_SLPS2R 0v
LDO_RTC 1.50

[phantomEVO]

i don't know if it is a good part...i can try to buy a brand new u7650..

[phantomEVO]

i've check each pin...there no shorts....i'm going crazy....

[phantomEVO]

PP3V3_G3H_RTC and PP3V3_G3H RTC_R are 3,3v

PP3V3_G3H is 2,6v

[mon2]

This voltage is defined by the feedback resistors on pin P3V3G3H_VFB2 of U7650. Assuming this power rail is not shorted, remove all power, measure each resistor between this pin # 16 and the output of the same power rail. Each resistor must be 1% accurate to properly output this voltage.

So test the resistance (without power) of:

R7655
R7691
R7697
R7698
R7699

[phantomEVO]

ALL OK EXCEPT R7698
R7699

BOTH MEASURE 35K...

but i have a "semi-donor board" (820-1521) and they have the same value

[phantomEVO]

edit

[phantomEVO]

can we start from the beginning? following some power sequence flow chart????

[phantomEVO]

i've ppbus_g3h @12,31

now ? which voltage must i have?

[mon2]

https://logi.wiki/index.php/PPBus_G3H

[phantomEVO]

??! ppbus is ok...

[mon2]

https://boards.rossmanngroup.com/thr...k-at-5v.62436/

[phantomEVO]

mon2...i really don't understand....the board you linked me is totally different from mine

and i have pp3v3_g3h_rtc

[mon2]

You are not working with the 820-01958 board?

The takeaway from the shared link is:

We have the main power rail PPBUS_G3H - 12.28v (should be 12.60v). But it should be 12.60v.

[phantomEVO]

i don't undersdtand......is mine ppbus wrong?!??!

according to this

https://repair.wiki/w/MacBook_Air_A2...w_at_5V_repair

you are right!!!

A good spot to measure from on the 820-01958 is C6482.

• ≈12.60–12.65 V = Normal, ≈12.28–12.35 V = T2 communication issue with the ISL9240. The likely cause for this is the device is stuck in DFU mode due to corrupt T2 firmware. Proceed to repair steps below for corrupt T2 firmware.

YOU ARE A LEGEND!! so i have to fix ppbus_g3h!!!! how??? diode value is ok

[phantomEVO]

it is not recognized in dfu....

[phantomEVO]

• i've already changed isl9240 some post before...with no luck and R7021, R7022, R7061, R7062 are ok

[mon2]

A lot has happened in this long thread..so check again:

voltage to ground on

SMBUS_3V3_BATT_SCL
SMBUS_3V3_BATT_SDA

What is the voltage and current draw on the USB-C meter at this time? Is it stable?

[phantomEVO]

Yes you are right!

at the moment
i have ppbus_g3h @ 12,31v
pp3v_g3h @ 2,6v

no shorts around usb c controller
no dfu mode (i have no 1V8_SLPS2R)


Ok both ports i have 5v @ 0,046 stable

[phantomEVO]

(without battery)

SMBUS_3V3_BATT_SCL
SMBUS_3V3_BATT_SDA
both 2,6 V unstable: it goes from 2,5 to 2,6 in a slow loop

https://www.dropbox.com/scl/fi/53ax3...=37a2qdh0&dl=0


if can be usefull, voltage of pmu

PP1V1_SLPS2R 0v
PP1V8_SLPS2R 0b
LDO_CORE 1,49v
PP0V8_SLPS2R 0v
PP1V2_AWAKE 0v
PMU_LDO3_OUT 1,79v