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820-01949 boot issue

K

Kyle93

Active member
This arrived with very little liquid damage. After removing C6501-C6503 and C6405 board started to boot with 20v for a few seconds but boot looped and then was stuck at 5v.

Reviving T2 in DFU solved the 5v issue. The machine now turns on and boots into the OS. The issue is when you go to restart the machine it will not turn back on, same applies to shut down and attempt to turn back on. The battery needs to be disconnected/reconnected for it to turn back on again.

Another observation is after reconnecting the battery the master usb-c port will be stuck at 5v 0amp but all other ports will work fine however after inital power on using any other port that port works fine again at 20V.

Battery is aftermarket that was replaced by someone else. OS says its normal and passes apple diagnostic. Not sure if that could be causing this issue?

What should be tried next?
 
2informaticos

2informaticos

Administrator
Staff member
Possibly Hall sensor issue.
Check LID_OPEN_LEFT/RIGHT and IPD_LID_OPEN.
Machine comes back from suspend, when you close/open the lid?
 
K

Kyle93

Active member
LID_OPEN_LEFT/RIGHT and IPD_LID_OPEN are all present 1.8v

A new observation is when the board alone is on the desk the left ports boot to 20v but the right is only 5v 0.25amps. Tried reflashing UB260 but no change

All LDOs are present on U3100W/U3100R
 
K

Kyle93

Active member
This is JB200 can these missing pads and trace damage around JB200 cause any issues even though JB200 is no stuff?
 
K

Kyle93

Active member
Affected area was cleaned and looks good.

Board now turns on using the left side usbc ports only. The right side does not work at all. Customer does not mind right side not working though.

The new issue is once the machine is shut down it will not come on again until the battery flex is unplugged and plugged back in. Using known good battery.

What else could cause this issue?
 
K

Kyle93

Active member
PMU_RSLOC_RST_L is 3.3v wether lid is closed or opened.

yes machine wakes up correctly when close/open the lid

When battery needs to be unplugged/replugged to turn machine back on after shutting down the message your computer has restarted because of a problem message appears
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Check if any error pops up starting in diagnostic mode.
Inspect Q8251 and related resistors.
Do the same for Q8170/1.
 
2informaticos

2informaticos

Administrator
Staff member
That is correct in off state.
What about the other MOSFETs mentioned?
Be sure the discharge resistors are good too (5.1-10 ohm).
 
K

Kyle93

Active member
All of the mosfets look pristine. No issues found in diagnostic mode. The issue does not occur until after the macbook has been shut down for a extended period of time
 
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