820-4924 reboots every 10 seconds.

[ajdoc]

Cant find any liquid on board.

Tested with genuine 85W charger.
Had only charging symbol on display even when left on charge for 30 minutes and press power button there was charging symbol.

Tested with two new and working batteries and it boots, but reboot every 10 secs.
Got Apple logo on screen and loading bar.
During boot when I unplug charger it shut down but I am sure batteries got charge.

Tested with new keyboard, trackpad, removed SSD and unpluged small board and camera flex - same issue.

Any idea?

 

[JohnB8812]

So it seems like it doesn't run off the battery. Will it boot without the battery plugged in? Any history drop liquid etc? Inspect very closely for any hints of corrosion near the ISL6259, SMC, U1900, U1950, the BIOS, and U7090.

 

[2informaticos]

Exact voltage for PPBUS_G3H?
Do you note battery voltage slowly increasing when both charger and battery are connected?

 

[ajdoc]

JohnB8812 - won?t boot without battery - board looks clean, no liquid - client say there was no drop

2informaticos - PPBUS_G3H got 12.55V
?Do you note battery voltage slowly increasing when both charger and battery are connected?? yes

 

[2informaticos]

Does it run in SMC bypass mode?
Post voltage for pins 9 & 15 of U7100.
Check exact value in ohm for R7121/22 and R7151/52.

 

[JohnB8812]

It should boot from just the charger. As 2informaticos suggested, measure resistance between pins 17/18 and 27/28 of the ISL6259

 

[ajdoc]

Yes, it does run in SMC bypass mode.

U7100/9 @ 0.035V
U7100/15 @ 0.060V

R7121 @ 10.5Ohm
R7122 @ 10Ohm

R7151 @ 2.3Ohm
R7152 @ 0.2Ohm

Resistance on ISL6259:
17/18 @ 3.7Ohm
27/28 @ 20.7Ohm

 

[2informaticos]

"Yes, it does run in SMC bypass mode."
So there is a sensor issue.
Check all sensors output from pages 42-45...

 

[ajdoc]

Don?t know if did good measurements - got zero experience with sensors.

Had only known good battery connected and 85W charger.

SMC_CPU_HI_ISENSE @ 0.299V
SMC_OTHER5V_HI_ISENSE @ 0.030V
SMC_OTHER3V3_HI_ISENSE @ 0.004V
SMC_LCDBKLT_ISENSE @ 0.005V
SMC_TPAD_ISENSE @ 0.007V
SMC_PBUS_VSENSE @ 2.141V
SMC_DCIN_VSENSE @ 2.668V
SMC_DCIN_ISENSE @ 0.360V
SMC_BMON_ISENSE @ 0.1V
SMC_PCH_ISENSE @ 0.008V
SMC_DDR_ISENSE @ 0.0V
SMC_CPUDDR_ISENSE @ 0.030V
SMC_PP3V3S0_ISENSE @ 0.008V
SMC_PP5VS0_ISENSE @ 0.010V
SMC_CPU_ISENSE @ 0.032V
SMC_SSD_ISENSE @ 0.0V
SMC_CPUHI_COMP_ALERT_L @ 1.455V
SMC_DDR1V8_ISENSE @ 0.015V
SMC_TBT_ISENSE @ 0.015V
SMC_LCDPANEL_ISENSE @ 0.007V
SMC_CAMERA_ISENSE @ 0.030V

ISNS_CPUHIGAIN_P @ 3.32V
ISNS_CPUHIGAIN_N @ 3.272V

SMC_BMON_COMP_ALERT_L @ 0.0V
SMC_BMON_DISCRETE_ISENSE @ 0.030V
SMC_CPU_VSENSE @ 1.85V
SMC_CPU_IMON_ISENSE @ 0.160V

TBTTHMSNS_THM_L @ 0.160V
TBTTHMSNS_ALERT_L @ 0.160V

CPUTHMSNS_THM_L @ 3.105V
CPUTHMSNS_ALERT_L @ 0.013V