baglai.vlad
Member (✔)
Hi everyone! At first, I am not a professional repair technician. I repair MacBooks and iPhones from time to time. So eventually I need some help from experienced professional people. Hope to get such help here.
Got my hands on MB Pro A1989 (820-00850-A) which does not turn on at all. USB meter shows 5V 0.28A on all 4 Type-C ports (w/o battery). No looping, all 4 ports consumes the same power. The board does not have any evidence of previous repairs, except the display was obviously replaced before. There is no corrosion as well, except some tiny around R3009, R3008 near U3000. I am not sure if it's even a corrosion or some dust, it was successfully cleaned with IPA. I think there is some evidence of liquid on Type-C ports itself (not on the board, but on detachable ports) on the same side (which connects to U3100, U3200), but it's hard to tell for sure. I can't see any corrosion on or around any of 4 CD3215s. Neither I can see any obvious faults (like burned ICs or mosfets around CD3215).
Diagnosis (followed repair.wiki and CD3215 Bootup Sequence):
PPBUS_G3H - 12.6V, present, stable
PP20V_USBC_XB_VBUS - 5V, present
PP3V3_UPC_**_LDO - 3V3, present, for all 4 CD3215s
PP1V8_UPC_**_LDOA - 1V8, present, for all 4 CD3215s
PP1V8_UPC_**_LDOD - 1V8, present, for all 4 CD3215s
PP1V1_UPC_**_LDO_BMC - 1V1, present, for all 4 CD3215s
UPC_**_GATE1 - around 7V8 for all 4 CD3215s (7V8 if the IC is active, 5V0 if another IC is active)
UPC_**_GATE2 - around 7V8 for all 4 CD3215s (7V8 if the IC is active, 5V0 if another IC is active)
PPDCIN_G3H - 5V0, present
PP3V3_G3H - 3V3, present and stable
USBC_XA_CC1, USBC_XB_CC1, USBC_TA_CC1, USBC_TB_CC1 - can see communication using oscilloscope on all 4 CD3215s.
Diagnosed MLB with thermal camera, nothing gets noticeable hot. All CD3215s are not hot when the power is connected. None of them stands out.
Tried to boot it into DFU mode, it worked, but reviving or restoring process fails with error "Gave up waiting for device to transition from DFU state to DFU state. [com.apple.MobileDevice.MobileRestore – 0xFCA (4042)]".
Before heating or soldering anything on the board, decided to reach for some help in understanding what is actually is going on.
My thoughts are: all CD3215s are seems to be fine, PPBUS_G3H is not shorted, T2 part is working (I assume so because the laptop is capable of booting into DFU). Thus, my only suspects are bad CD3215s ROM ICs (U2890, UB090), but diode mode readings on its pins are OK. Unfortunately, currently I don't have neither A1989 donor board nor programmer for these ICs.
What are your thoughts?
Got my hands on MB Pro A1989 (820-00850-A) which does not turn on at all. USB meter shows 5V 0.28A on all 4 Type-C ports (w/o battery). No looping, all 4 ports consumes the same power. The board does not have any evidence of previous repairs, except the display was obviously replaced before. There is no corrosion as well, except some tiny around R3009, R3008 near U3000. I am not sure if it's even a corrosion or some dust, it was successfully cleaned with IPA. I think there is some evidence of liquid on Type-C ports itself (not on the board, but on detachable ports) on the same side (which connects to U3100, U3200), but it's hard to tell for sure. I can't see any corrosion on or around any of 4 CD3215s. Neither I can see any obvious faults (like burned ICs or mosfets around CD3215).
Diagnosis (followed repair.wiki and CD3215 Bootup Sequence):
PPBUS_G3H - 12.6V, present, stable
PP20V_USBC_XB_VBUS - 5V, present
PP3V3_UPC_**_LDO - 3V3, present, for all 4 CD3215s
PP1V8_UPC_**_LDOA - 1V8, present, for all 4 CD3215s
PP1V8_UPC_**_LDOD - 1V8, present, for all 4 CD3215s
PP1V1_UPC_**_LDO_BMC - 1V1, present, for all 4 CD3215s
UPC_**_GATE1 - around 7V8 for all 4 CD3215s (7V8 if the IC is active, 5V0 if another IC is active)
UPC_**_GATE2 - around 7V8 for all 4 CD3215s (7V8 if the IC is active, 5V0 if another IC is active)
PPDCIN_G3H - 5V0, present
PP3V3_G3H - 3V3, present and stable
USBC_XA_CC1, USBC_XB_CC1, USBC_TA_CC1, USBC_TB_CC1 - can see communication using oscilloscope on all 4 CD3215s.
Diagnosed MLB with thermal camera, nothing gets noticeable hot. All CD3215s are not hot when the power is connected. None of them stands out.
Tried to boot it into DFU mode, it worked, but reviving or restoring process fails with error "Gave up waiting for device to transition from DFU state to DFU state. [com.apple.MobileDevice.MobileRestore – 0xFCA (4042)]".
Before heating or soldering anything on the board, decided to reach for some help in understanding what is actually is going on.
My thoughts are: all CD3215s are seems to be fine, PPBUS_G3H is not shorted, T2 part is working (I assume so because the laptop is capable of booting into DFU). Thus, my only suspects are bad CD3215s ROM ICs (U2890, UB090), but diode mode readings on its pins are OK. Unfortunately, currently I don't have neither A1989 donor board nor programmer for these ICs.
What are your thoughts?
