820-01958-A Macbook Air 2020 A2179 No Power

[fozzo]

Hello guys, I need some guidance to repair this board.

History

Board came to me after being inspected by another shop and declared dead. Previuosly water damage only in the ISL9240 area. Previous tech guy removed ic and make an horrible scratch game under it. By luck no pad were ripped off but nc ones. Then he soldered back U7000 on the up side down.

What I've Done so Far

I removed isl (u7000), clean and soldered back a new one. On my usb ammeter I had 20V so put motherboard back inside, assembled and macbook started. After a couple of minutes of testing i heard a click and macbook power off. I went to check motherboard, at this point usb ammeter didn't give any data. I found out PPDCIN_G£H_CHR_AMON was shorted to ground. I removed every single component on that line but the short was still there so I supected an internal line short. I rebuilt all the line outside of the board and put all component back from R7020 to U7000 pad. Line has 5V as it should but no switch to 20V on ammeter. PPBUS_G3H is cycling from 1.2V to 0.9V in a loop. LDO (3.3V and 1.5V) for bot CDs are present and stable. Just to be sure I changed U7000 again but still same behaviour. On ammeter I now have 5.2V 0.1A.

Any idea where to look?

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Remove the downstream fuse on PPBUS_G3H and check if PPBUS_G3H becomes stable.

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Do you mean F8000? it seems to be the only fuse on PPBUS_G3H. By the way thanks for your answer.

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Ignore my fuse comment for now. Was hoping we could isolate the ISL9240 to validate this section for PPBUS_G3H is stable.

Remove the battery (if connected).

1) Meter in resistance mode -> check the resistance to ground of PPBUS_G3H. What is the reading ? If this reading is too low, then there is a short or damaged part downstream.

2) Do review the following great article by @Piernov that details how the CD3215 (CD3217 will be similar) devices must operate before the 20V contract is selected for the power delivery to power this logic board.

https://www.logi.wiki/index.php/CD3215_Bootup_Sequence

Check and post the resistance readings to ground for the USB D+ / D- lines.

3) What is the voltage of PPDCIN_G3H?

4) Confirm that the 2 * fuses (one for each ACE CD3217 controller) are ok. See attached.

We need 20V before U7000 can work but good to check the following.

5) Confirm that for the ISL9240, the current sense resistor and associated parts that mate with the ISL9240 are present. If the current sense loop circuit is not completing, then this buck convertor will shut off or enter chirp mode thinking too much current is being drawn to prevent damage.

So specifically, confirm that CSIN / CSIP parts are ok.

Confirm CSON / CSOP parts are ok.

Confirm the power rails are present for the U7000 (ISL9240). Consider to use good amount of flux with low air + high heat to make the IC 'dance'. If you are confident on the soldering of this part - leave it alone for now.

6) Confirm that the mosfets linked to U7000 are not shorted. Check the resistance between:

Source & DRAIN
Source & GATE
Gate & DRAIN

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

1) resistance to ground for PPBUS_G3H is more than 11kohm
2)
USBC_X_R2D_N<2> 216khom
USBC_X_R2D_P<2> 223kohm
USBC_X_D2R_CR_N<2> 210kohm
USBC_X_D2R_CR_P<2> 210kohm
USBC_T_R2D_P<1> 214kohm
USBC_T_R2D_N<1> 216kohm
USBC_T_D2R_CR_P<1> 220kohm
USBC_T_D2R_CR_N<1> 220kohm
USBC_T_D2R_CR_P<2> 220kohm
USBC_T_D2R_CR_N<2> 220kohm
USBC_T_R2D_P<2> 220kohm
USBC_T_R2D_N<2> 218kohm
USBC_X_D2R_CR_P<1> 223kohm
USBC_X_D2R_CR_N<1> 216kohm
USBC_X_R2D_P<1> 227kohm
USBC_X_R2D_P<1> 218kohm

(reading piernov article now but I already read for an a1706 which had a problem with on CD and which you helped me solving)

3) PPDCIN_G3H 5.20v stable
4) Both fuses have continuity
5) CSIN / CSIP looks ok both resistors have 1.1ohm resistance (schema states 1.0)
CSON / CSOP schema states both resistors should have 1.0ohm but they measure 37.8 ohm both
For the power rails for U7000
PPDCIN_G3H_CHGR_AMON 5.2v stable
PPDCIN_G3H:
5.20V on pin1 of R7015 and 1.35V on pin 2
C7023 5.20V both pin
CHGR_BOOT1 5.07V
CHGR_BOOT2 5.07V
CHGR_LX1 0v
CHGR_LX2 0v
CHGR_CSO_P 1.08 - 1.12V not stable
CHGR_CSO_N 1.08 - 1.12V not stable
PPCHGR_VDDA 5.05v
PPCHGR_VDDP 4.98v

I'm familiar with soldering ic so I'm quite sure this is well soldered.

How do I check resistance forsource & drain etc?

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

How do I check resistance forsource & drain etc?

Please review the resistance chart on this great webpage:

http://electronicsbeliever.com/how-t...-is-defective/

Then remove all power -> meter in resistance mode and check for possible shorted mosfets linked to U7000.

CSON / CSOP schema states both resistors should have 1.0ohm but they measure 37.8 ohm both For the power rails for U7000

That is interesting. Can you probe the resistance between the parts to locate a possible fault?

Measure the resistance C7020, pin 1 & R7061, pin 1. Value ?

Then continue to check resistance C7020, pin 1 & R7061, pin 2. Value ? Should only be + 1 ohms between these 2 points, etc. Continue to test this current loop circuit. The readings should match the schematic values.

Expecting to hear the resistance between CSON & CSOP to be about 2 ohms.

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Very cool article! Got it so

Q7040
Source & DRAIN 60kohm
Source & GATE 14mohm
Gate & DRAIN 100mohm

Q7030
Source & DRAIN 32kohm
Source & GATE 100mohm
Gate & DRAIN 100mohm

Do you see anything wrong with all my readings?

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Do you see anything wrong with all my readings?

No. These mosfets look ok. Please continue to investigate others (Q7065 & Q7070).

Also interested to hear about your progress on CSON / CSOP loop of parts.

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Something changed on this board making me crazy

R7062 now is 743ohm
R7602-1 -> C7020-1 = 743ohm
R7602-2 -> C7020-1 = 2ohm

R7061 now is 4.9kohm
R7601-1 -> C7020-2 = 4.9kohm
R7601-2 -> C7020-2 = 2ohm

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Will update you tomorrow morning my time for Q7065 & Q7070, dinner time here I'm going to close the shop

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Here the two mosfet:

Q7065
Source & DRAIN 8mohm
Source & GATE 110mohm
Gate & DRAIN 110mohm


Q7070
Source & DRAIN 149kohm
Source & GATE 283kohm
Gate & DRAIN 4mohm

I also double checked r7602 and r7601 same reading as previuos post. I realized those probably changed after I removed and solder again u7000 (just to be sure it was well soldered) Also ammeter now says 0.3a 5.2V, I'm going to check all previous readings to see if anything changed and I will post back.

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Oksomething different here too:

CHGR_BOOT2 now oscillates between 5.33 and 5.38v
CHGR_LX1 and CHGR_LX1 0.40v

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

These mosfets are ok.

Remove all power, meter in resistance mode, check the resistance to ground for these power rails. What are the readings?

Do the same for each coil on board.

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Sorry for late answer, I've been able to take readings only now and here they are

PPDCIN_G3H 61kohm
PPDCIN_G3H_CHGR_AMON 61kohm
R7015 pin 2 190kohm
C7023 62kohm both pin
CHGR_BOOT1 160mohm
CHGR_BOOT2 180mhom but its not stable
CHGR_LX1 100mohm
CHGR_LX2 100mohm
CHGR_CSO_P 170kohm
CHGR_CSO_N 170kohm
PPCHGR_VDDA 700khom
PPCHGR_VDDP 700kohm

L7701 1.6kohm
L7700 1.6kohm
L8150 400ohm
L6700 100kohm
L6400 1mohm
L6401 1mohm
L8410 10mohm
L8100 4.9ohm
L7400 373ohm
L7230 256ohm
L7220 256ohm
L7210 256ohm
L7030 90mohm
L7690 60kohm
L7670 50kohm
L9070 16kohm

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

Do you see anything wrong? Anything else to check

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

hi.

1) L8100 looks low but it is a low voltage rail so this range may be acceptable. Perhaps others can share their comments on this resistance.

2) Power down. Meter in DIODE mode.

Red meter lead to ground (yes ground).

Black meter lead to:

USBC_X_CC1 - what is the reading ?
USBC_X_CC2

USBC_T_CC1
USBC_T_CC2

The CCx lines are used by the Power Delivery interface to exchange packets between the power provider (adapter) & the power consumer (logic board).

Respectively, these CCx lines must be working for the communication to dial up the higher 20V rail or essentially anything higher than 5V0 (default).

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

hello here they are

USBC_X_CC1 .568
USBC_X_CC2 .568

USBC_T_CC1 .570
USBC_T_CC2 .570

by the way diode reading of L8100 is .005

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

I'm looking at L8100, i loose pin 2 to separate two lines
pin 1 P1V1_PHASE diode is .434 resistance 17kohm
pin 2 PP1v1_S3 diode is .004 resistance 4.5ohm
Looks to me that pin 2 is not full short but doesn't look correct be an s3 line with low voltage, am I wrong?

[mon2]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

See here, but welcome advice from others...

https://boards.rossmanngroup.com/thr...-a-dead.60761/

[fozzo]

Re: 820-01958-A Macbook Air 2020 A2179 No Power

I see.... so you think cpu is fried. I wonder if is safe to inject 1 volt in this line to see if anything heat but i don't think as it should be shorted to ground or if I just give back to costumer as no repair.