820-00165 no power

Kyle93

Active member
Arrived with the classic exploded capacitor causing short on PPBUS_G3H. Replaced cap which restored PPBUS_G3H but still no power.

PM_SLP_S4_L 0V

PCH_SUSACK_L 3.3V

PM_SYSRST_L 0.52V

PM_BATLOW_L 3.3V

SMC_ADAPTER_EN 3.3V

PM_RSMRST_L 3.3V

ALL_SYS_PWGD 0V

What next?
 

Kyle93

Active member
If you tap the the bottom side of the board in CPU section at times the fan will spin and boot properly according to bench power supply but only for a few seconds to a couple minutes then turns off again.

Does this sound like a internal problem with the new behavior?
 

2informaticos

Administrator
Staff member
Test the board alone on the desk; do not connect LIO flex.
Also try with original Magsafe 2 charger.
 

Kyle93

Active member
During testing noticed L7560 voltage was fluctuating. A couple times the fan even spun during the test. Replaced Q7560 but no change. Should U7501 be replaced?

Yes there is a pulse at ALL_SYS_PWRGD
 

2informaticos

Administrator
Staff member
Check for pulse at pins 7 & 3 of U1950.
Inspect all SPI Bus Termination resistors and their traces.
PLT_RESET_L pulses too?
Any pulse detected at CPU coils?
 

Kyle93

Active member
yes pins 7&3 pulse. While testing pin 3 the fan started spinning and stayed spinning until unplugged. After unplugged and test again no fan spin.

termination resistors are traces are fine

PLT_RESET_L pulses

no pulse at CPU coils
 

2informaticos

Administrator
Staff member
Pin 3/U1950 and PLT_RESET_L cannot pulse, if no pulse at VCORE too; which is not easy to detect.

3V3_S5 and C7540 voltages are steady high when trigger SMC_ONOFF_L?
Check for voltage pulse, or short, at pages 57 & 58.
 
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