A2485 MBP16 M1 820-02100 not charging

[flusher]

Bought myself a project. Waterdamage to the left wing. Front side got damage on top up to SSD area. Back - near CD3218 both CD3217. Had to replace a lot of caps and resistors to make it perfect. No shorts. Didnt lift any chips yet but microscope shows good balls from sides. Anyway. It powers up and boots fine.
Right single usbc shows 20v on meter 0 amp
Left upper usbc shows 5v 0 amp
Left bottom usbc shows 20v 0 amp
magsafe shows orange but also does not charge
nothing produces beep from mac when on
when off - single usbc and magsafe produce beep but no beep for upper and lower usbc on left side
also single on right usbc works for data usb flash drive
while both on left side usbcs are not

now my guess is that magsafe that is based on cd3218 should work even if any usbc on cd3217s aren’t good so i decided to look into it first. All powers and ldos are fine. I measured all voltages and all diode measurement are same as OBdata on boardview. I measured all resistor values and double checked everything i replaced. All should be good. I am getting to the point where it has 28v and CC line is 1.6v but it doesnt operate those two big mosfets to pass high voltage to battery charger IC. Any help with that?

Appreciate any 🙏

[mon2]

Is the battery being detected? If not, review the SMBUS interface on the battery BMS to the logic board.

Measure the voltage to ground on each pin of the battery connector with the power adapter powering the board. Post each measurement. Testing if the SMBUS lines are ok or not.

[flusher]

Battery being detected, percentage, health and cycle count can be viewed, machine boots up normally. Should i still proceed with measurements?

[mon2]

No. SMBUS lines are working fine.

What is the cycle count on the battery that is mated to the board?

When you attach the OEM power adapter to the port with 20v support, what is the PPVBAT_AON voltage to ground on the battery connector? This PPVBAT_AON voltage should be slightly higher than the voltage markings on the pack for it to charge.

Next, remove all power. Meter in resistance mode. Measure the resistance to ground of PPVBAT_AON. We are testing if there is a shorted part on this rail. Do not have the battery connected during this test. Only testing if perhaps a local capacitor is shorted on this power rail.

[flusher]

no battery connected PPVBAT_AON on fuse F5200 is 36kOhms and growing
battery has 92 cycles 95% health

the problem is not with the battery IMO. we have no high voltage coming to PPDCIN_AON_CHGR from neither USBC or MAGSAFE so we can't expect anything to charge. unless there is an error in communication between charger itself and any power source ic CD32## that is supposed to provide that high voltage.
battery charger ic area is clean as a whistle.



while machine is off measuring F5200 (PPVBAT_AON) - 11.21v

now using 140w apple genuine brick 100% working tested on other a2485 machine:

connected to magsafe
machine off - meter 5v 1A. hear gong. battery 11.28v. maybe it even charges like this if left overnight. PPDCIN_AON_CHGR 4.9v.
machine on - meter switching all way to 28v current 0.0063A. no gong. battery voltage same or below. sys info shows no ac charger connected and charging no. orange light. PPDCIN_AON_CHGR 0v

connected to right single usbc
machine off - meter 5v 1A. hear gong. battery 11.28v. maybe it even charges like this if left overnight. PPDCIN_AON_CHGR 4.9v
machine on - meter 20v 0a. no gong. battery voltage same or below. sys info shows no ac charger connected and charging no. PPDCIN_AON_CHGR 0v

connected to left upper usbc
machine off - meter 5v 0.0046A. no gong. battery voltage same or below.
machine on - meter 5v 0a. no gong. battery voltage same or below. sys info shows no ac charger connected and not charging
in any case PPDCIN_AON_CHGR 0v

connected to left bottom usbc
machine off - meter 5v 1A. NO gong. battery 11.28v. maybe it even charges like this if left overnight. PPDCIN_AON_CHGR 4.9v. a bit weird as sometimes it is 20v 0A. sometimes it is 5v 1A and causes machine to power up with apple sound fully even closed clamshell.
machine on - meter 20v 0a. no gong. battery voltage same or below. sys info shows no ac charger connected and charging no. PPDCIN_AON_CHGR 0v

all ports were removed and inspected, perfectly fine. also checked reverse insertion.

those two left USBCs seem to either share something that prevents them from working or something that is specific to upper one which is failing and bringing down bottom one as well. i am puzzled to what it could be.

also magsafe should be independently working from all usbc but no, is there a confirmation on that?



U5500 CD3218 was not replaced but all small components around it checked all good

UF400 got more area damaged around than UF500 which somewhat explains it is stuck on 5v

any other measurements i could provide?

[mon2]

machine on - meter switching all way to 28v

?? Is this a typo? 28v? This is way beyond spec. This must be 20v. Test with another known good power adapter. 28v is extremely high.

Be sure your meter batteries are fresh as a weak battery can throw off the measurements.

Update:

Measure the voltage to ground of PPDCIN_AON.

If this voltage is truly > 24v then the zener @ DZ5341 will trigger. Confirm this voltage.

[flusher]

magsafe 3 is a PD 28V 5A 140W and it is a normal voltage for it
usbc is 20v 5A only

in which scenario you want me to measure PPDCIN_AON ?

do you need schematics? i can provide

[mon2]

Did not know that magsafe 3 is now 28v.

Have the schematics in my paid service out of China.

Connect the magsafe but leave the unit off. Measure PPDCIN_AON and PPDCIN_AON_CHGR .

Turn the unit on and measure the same points again.

[flusher]

ok cool
connected to magsafe
machine off - meter 5v 1A. hear gong. PPDCIN_AON 0v and PPDCIN_AON_CHGR 4.85v .
machine on - meter switching all way to 28v current 0.0063A. no gong. PPDCIN_AON 0v and PPDCIN_AON_CHGR 0.2v.

can confirm that when i left machine off with magsafe and it draws 5v 1a it actually charged 5% up to the battery so the charger ic is actually boosting 5v to charge the battery as in some kind of emergency mode.

[mon2]

Flux and remove DZ5341. Note that the 24v clamping feature will be lost but it appears that this is not working anyways.

Best to replace this part to test again with a 24v zener in place. When working, this line should not exceed 24v but should be present and not tanking to 0v.

Respectively, IF this part is removed, then the PPDCIN_AON rail will be hit with the peak adapter voltage so concerned here. Apple has this 24v zener in place for a reason and it is to keep this rail at 24v or UNDER.

[mon2]

Here is an idea - flux and remove U5350 and also the mosfet @ Q5340. This will protect the downstream rails through isolation.

Now experiment. Do you see 24v at the zener when the adapter is at 28v? If not, the zener is defective.

[flusher]

can you explain the theory here? i am a bit reluctant to touch absolutely clean areas of the board to not mess up everything at once without validating it first.
PPDCIN_AON rail comes only from USBCs not magsafe so 24v zener actually makes sense because this is definitely 20v rail.
since you were asking about magsafe scenario there was 0v.
now to confirm that i can run this scenario:
connected to right single usbc
machine off - meter 5v 1A. both PPDCIN_AON and PPDCIN_AON_CHGR = 4.85v .

in case of magsafe it doesn't use this U5340 circuit (although mentioned on magsafe schematics page) it just pumps output voltage straight into PPDCIN_AON_CHGR through two big mosfets and F5601 fuse

i think 1MIL$ question is do we need working CD3217s for magsafe to work or not as it seems both single usbc side and magsafe are able to pass output 5v voltages while those two CD3217 ports are crippled. if not we might poke magsafe for no reason

[mon2]

Remove all power. Meter in resistance mode.

Measure the resistance across C5220. We are testing the full path resistance for the incoming current sense circuit. What is the exact resistance?

What voltages do you measure @ DCIN_VSENSE?

[flusher]

2.7 Ohms. multimeter might be not super precise tho

[mon2]

Looks ok. You can short / touch your meter probes together to get the baseline for your meter = '0R ohms'. Subtract this from your measurements to get a fairly accurate reading.

What is the voltage to ground of CHGR_AUX_DET?

[flusher]

ok a bit side off. i started looking into those two usbcs on left side.
obviously i have to remove the board and test/measure only on usbc plugged in, without battery where none of the port will boost to 20v
both shows 5v on meter.

upper port:
draw 0.0046A
1.5v ldo present
3.3v ldo present
CC pin 1.6v
but no output through fuse to PPDCIN_AON therefore charger is not boosting anything and cant produce all main system rails:
ppbus_aon 1.37v
pp3v3_s2 0v
pp1v2_s2 0v
pp3v8_aon 0v


bottom port:
draw fluctuates first 0-200mA as if board does something but then settles to something like 0.05A
1.5v ldo present
3.3v ldo present
outputs through fuse to PPDCIN_AON therefore charger is boosting and we have all main system rails:
ppbus_aon 12v
pp3v3_s2 3.3v
pp1v2_s2 1.2v
pp3v8_aon 3.8v
LF100 however has only 0.39v (supposedly 0.9v) - related to intel TBT controller

i did found UF115 had only 2.4v output instead of 3.3v and when desoldered input pin was corroded so i restored all this and now good 3.3v out but nothing else improved, long shot we might get usb data communication back on this port as it seem to be related only to that.

now puzzling what prevents upper CD3217 from giving that 5v output as basically all the rest do

when input is 5v and there is no battery:
CHGR_AUX_DET is 0.85v
DCIN_VSENSE is 0.25v