ytesfay80
Member
This board was sent in as not turning on. The light on the charger stays green and it doesn't turn on when I hit the power button or when I short the onoff pads.
Here are some measurements I took before replacing the U7200 chip.
CHGR_DCIN 16.35
CHGR_ACIN - 4v
PPBUS_G3h - 12.58
pp3v42_g3h- 3.41v
Resistance Pins 17/18 U7000 - 2.9ohms
Resistance Pins 27/28 U7000 - 20.2ohms
u5010 voltages were all fine.
shorted smc_onoff_l to ground and saw the voltage go to 0v on u5010 but still doesn't turn on
U7200 (Pin 1 - 0v - Pin 6 - 0.78v - Pin 16 - 12.58v)
SMC_PM_G2_EN - 3.4v
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Q7221 was showing 3.38v on pin 2 and 0v on the drain Pin 6 so I replaced the TPS51125(U7200)
There was still 0v on Pin 1 of U7200 so I replaced Q7221. Still made no difference.
I then checked Pin 16(VIN) of U7200 and noticed it wasn't a stable 12.58v. PPBUS_G3H starts off at 12.58v and quickly goes down to around 5v then jumps back up to 12.58v and repeats. I even took the TPS51125 off of the board and measured and PPBUS_G3H still does the same thing.
What could be causing this?
Here are some measurements I took before replacing the U7200 chip.
CHGR_DCIN 16.35
CHGR_ACIN - 4v
PPBUS_G3h - 12.58
pp3v42_g3h- 3.41v
Resistance Pins 17/18 U7000 - 2.9ohms
Resistance Pins 27/28 U7000 - 20.2ohms
u5010 voltages were all fine.
shorted smc_onoff_l to ground and saw the voltage go to 0v on u5010 but still doesn't turn on
U7200 (Pin 1 - 0v - Pin 6 - 0.78v - Pin 16 - 12.58v)
SMC_PM_G2_EN - 3.4v
----------------------------------------
Q7221 was showing 3.38v on pin 2 and 0v on the drain Pin 6 so I replaced the TPS51125(U7200)
There was still 0v on Pin 1 of U7200 so I replaced Q7221. Still made no difference.
I then checked Pin 16(VIN) of U7200 and noticed it wasn't a stable 12.58v. PPBUS_G3H starts off at 12.58v and quickly goes down to around 5v then jumps back up to 12.58v and repeats. I even took the TPS51125 off of the board and measured and PPBUS_G3H still does the same thing.
What could be causing this?