Dear colleagues, they brought to me this Apple Macbook Air, that has no signs of liquid spilling externally nor internally, no burned component, no wasted spots on the mainboard, no oxydations (even seeing with a big magnifier lens) and no signs of scratches or falling shocks.
Owner said that one morning it didn't start anymore.
If you connect the MagSafe, light is first green then orange, and that remains for the time being.
I heated gradually to 199°C most spots on the mainboard (even CPU, RAM, SMC etc) but nothing changed.
I unsoldered and resoldered the U6100 and many components around it, but nothing changed.
No component is heating even if the power is applid for many minutes.
I've made some measurements:
P3V3_S5 3.27
P3V3S5_EN 3.35
P5VP3V3_VREG3 3.23
PPDCIN_G3H 14.80
PPBUS_G3H 403 8.39 "shouldn't this be around 8,60v"?
PP3V42_G3H 277 3.36
PPRTC_G3H 414 3.26
PP5V_S5 430 4.94
PP5V_S4RS3 399 jump
PP3V3_S4 468 0.00 jump
PM_SLP_S4_L jump 1 time - 460 ***
RTC_RST_L 3.26
S5_PWRGD-->SMC 559 3.32
SMC-->PM_DSW_PWRGD
PM_DSW_PWRGD 3.35
SMC_RESET_L 486 3.32
PLT_RESET_L 509 0.00
SMC_ONOFF_L 675 3.34
SMC_BC_ACOK 470 3.23
SMC_PM_G2_EN 519 3.36
S5_PWRGD 564 3.32
PM_PCH_SYS_PWROK 742 0.00
SMC_ADAPTER_EN 548 3.35
PM_SYSRST_L 706 jumps *** 0.01
PM_PCH_PWROK 950 jumps *** 0.00
PCH_DSWVRMEN 792 3.16
PM_DSW_PWRGD 746 3.35
PCH_INTVRMEN_L 3.16
PM_PWRBTN_L 527 3.35 (->0.35 when SMC_ONOFF_L to 0)
PM_BATLOW_L 531 3.26
PP3V3_S5_AVREF_SMC 590 3.22
PM_RSMRST_L 627 3.23
PP1V2_S5_SMC_VDDC 482 1.18
PP3V3_S5_SMC_VDDA 280 3.35
ALL_SYSTEM_PWRGD 416 jump 1 time 0.00
U1950
1 ALL_SYSTEM_PWRGD 402 pulse
2 CPUVR_PGOOD_R 735 pulse
3 SYS_PWROK_R 694 NO pulse
4 GND
5 PM_S0_PGOOD 675 pulse
6 SMC_DELAYED_PWRGD 722 pulse
7 PM_S0_PGOOD 675 pulse
8 PP3V42G3H 280 3.36
U1900
1 PPVRTC_G3H 433 3.26
2 PP3V3_S5 335 3.27
3 SYSCLK_CLK25M_X2_R 434 0.00
4 SYSCLK_CLK25M_X1 430 ~0.54
5 PP3V3_S5RS3RS0_SYSCLKGEN 327 3.27
6 PP1V2_CAM_XTALPCIEVDD 315 0.00
7 GND
8 SYSCLK_CLK25M_CAMERA 438 0.00
9 NC 438 0.00
10 GND
11 GND
12 PCH_CLK32K_RTCX1 442 ~0.39
13 PP3V42_G3H 285 3.36
14 PP3V3_TBLC 390 0.24
15 SYSCLK_CLK25M_TBT 426 0.00
16 GND
What I see from these measurements is that, after having connected the (original working Apple) MagSafe most "after S5" signals make 1 jump and then they stay at 0 volts (I waited 5 minutes and no other jump occurs), you can see PM_SLP_S4_L , PM_SYSRST_L , PM_PCH_PWROK , most of signals from U1950, etc...
If I close SMC_ONOFF_L to GND , those same signals make another jump and they go to zero again.
If you see the measurements, shouldn't PPBUS_G3H be around 8,60v ?
The sad part is that I don't own an oscilloscope, so I can't measure frequencies, specially the ones from U1900, but since I don't see signals jumpin continually in cycle, my first suspect is that the problem maybe the U1900 itself.
What do you thins about?
Can you suggest something else?
Owner said that one morning it didn't start anymore.
If you connect the MagSafe, light is first green then orange, and that remains for the time being.
I heated gradually to 199°C most spots on the mainboard (even CPU, RAM, SMC etc) but nothing changed.
I unsoldered and resoldered the U6100 and many components around it, but nothing changed.
No component is heating even if the power is applid for many minutes.
I've made some measurements:
P3V3_S5 3.27
P3V3S5_EN 3.35
P5VP3V3_VREG3 3.23
PPDCIN_G3H 14.80
PPBUS_G3H 403 8.39 "shouldn't this be around 8,60v"?
PP3V42_G3H 277 3.36
PPRTC_G3H 414 3.26
PP5V_S5 430 4.94
PP5V_S4RS3 399 jump
PP3V3_S4 468 0.00 jump
PM_SLP_S4_L jump 1 time - 460 ***
RTC_RST_L 3.26
S5_PWRGD-->SMC 559 3.32
SMC-->PM_DSW_PWRGD
PM_DSW_PWRGD 3.35
SMC_RESET_L 486 3.32
PLT_RESET_L 509 0.00
SMC_ONOFF_L 675 3.34
SMC_BC_ACOK 470 3.23
SMC_PM_G2_EN 519 3.36
S5_PWRGD 564 3.32
PM_PCH_SYS_PWROK 742 0.00
SMC_ADAPTER_EN 548 3.35
PM_SYSRST_L 706 jumps *** 0.01
PM_PCH_PWROK 950 jumps *** 0.00
PCH_DSWVRMEN 792 3.16
PM_DSW_PWRGD 746 3.35
PCH_INTVRMEN_L 3.16
PM_PWRBTN_L 527 3.35 (->0.35 when SMC_ONOFF_L to 0)
PM_BATLOW_L 531 3.26
PP3V3_S5_AVREF_SMC 590 3.22
PM_RSMRST_L 627 3.23
PP1V2_S5_SMC_VDDC 482 1.18
PP3V3_S5_SMC_VDDA 280 3.35
ALL_SYSTEM_PWRGD 416 jump 1 time 0.00
U1950
1 ALL_SYSTEM_PWRGD 402 pulse
2 CPUVR_PGOOD_R 735 pulse
3 SYS_PWROK_R 694 NO pulse
4 GND
5 PM_S0_PGOOD 675 pulse
6 SMC_DELAYED_PWRGD 722 pulse
7 PM_S0_PGOOD 675 pulse
8 PP3V42G3H 280 3.36
U1900
1 PPVRTC_G3H 433 3.26
2 PP3V3_S5 335 3.27
3 SYSCLK_CLK25M_X2_R 434 0.00
4 SYSCLK_CLK25M_X1 430 ~0.54
5 PP3V3_S5RS3RS0_SYSCLKGEN 327 3.27
6 PP1V2_CAM_XTALPCIEVDD 315 0.00
7 GND
8 SYSCLK_CLK25M_CAMERA 438 0.00
9 NC 438 0.00
10 GND
11 GND
12 PCH_CLK32K_RTCX1 442 ~0.39
13 PP3V42_G3H 285 3.36
14 PP3V3_TBLC 390 0.24
15 SYSCLK_CLK25M_TBT 426 0.00
16 GND
What I see from these measurements is that, after having connected the (original working Apple) MagSafe most "after S5" signals make 1 jump and then they stay at 0 volts (I waited 5 minutes and no other jump occurs), you can see PM_SLP_S4_L , PM_SYSRST_L , PM_PCH_PWROK , most of signals from U1950, etc...
If I close SMC_ONOFF_L to GND , those same signals make another jump and they go to zero again.
If you see the measurements, shouldn't PPBUS_G3H be around 8,60v ?
The sad part is that I don't own an oscilloscope, so I can't measure frequencies, specially the ones from U1900, but since I don't see signals jumpin continually in cycle, my first suspect is that the problem maybe the U1900 itself.
What do you thins about?
Can you suggest something else?
