A1990 DEAD

[Arshad alam4659]

I Have a a1990 820-01041-a no power
PP3V3_G3H_RTC_X= 3.3v
PP3V3_UPC_TA_LDO=3.3v
PPBUS_G3H=12.4v
dc is showing 5v stuck 200 ma
what problem anyone help

[mon2]

Are you power cycling?

4v88 is considered low. Check the cd3215 - each ldo on these parts must be working.

Review this thread:

https://repair.wiki/w/MacBook_Pro_A1...k_at_5V_repair

[Arshad alam4659]

Are you power cycling?

4v88 is considered low. Check the cd3215 - each ldo on these parts must be working.

Review this thread:

https://repair.wiki/w/MacBook_Pro_A1...k_at_5V_repair

yes one cd3215 was bad i was changed cd3215 now condition normal 20v
but also no power on can you suggest what next check

[mon2]

What is the current draw now? Do you have power cycling? What is the voltage to ground of ppbus_g3h?

[Arshad alam4659]

What is the current draw now? Do you have power cycling? What is the voltage to ground of ppbus_g3h?

PPBUS_G3H =12.5V

[mon2]

Measure the voltage to ground of ALL_SYS_PWRGD. You may measure at TPC4F9.

Also, interested in the voltage to ground of:

SMBUS_3V3_BATT_SCL
SMBUS_3V3_BATT_SDA

[Arshad alam4659]

Measure the voltage to ground of ALL_SYS_PWRGD. You may measure at TPC4F9.

Also, interested in the voltage to ground of:

SMBUS_3V3_BATT_SCL
SMBUS_3V3_BATT_SDA

SMBUS_3V3_BATT_SCL=3.40V
SMBUS_3V3_BATT_SDA=3.40V

[Arshad alam4659]

ALL_SYS_PWRGD= 0V

[mon2]

This means that at least one of the power rails is not good. Remove all power / no battery. Meter in resistance mode.

Measure the resistance to ground of each and every inductor (usually grey in color; 2 leads) to ground. We are checking for a low resistance that may indicate a defective or shorted part is on that rail. If there is an excessive current draw, that local rail will shut off and cause the ALL_SYS_PWRGD line to be stuck low '0' = 0 volts.

Post all suspects.

[Arshad alam4659]

This means that at least one of the power rails is not good. Remove all power / no battery. Meter in resistance mode.

Measure the resistance to ground of each and every inductor (usually grey in color; 2 leads) to ground. We are checking for a low resistance that may indicate a defective or shorted part is on that rail. If there is an excessive current draw, that local rail will shut off and cause the ALL_SYS_PWRGD line to be stuck low '0' = 0 volts.

Post all suspects.

P5VUSBCT_R=0L
P3V3G3H_VSW=0L
PP0V95_S0_CPUVCCIO_REG_R=54.1OHM
CHGR_PHASE2=0L
P1V2_PHASE=0L
PPVIN_S0SW_LCDBKLT=0L
VR_PHASE_GPU_VDDCI=28.7OHM
GPUFB_LL=0L
PPVCORE_S0_GFX_PH1=1.7OHM
PPVCORE_S0_GFX_PH3=1.7OHM
PPVCCSA_CPU_R15.5OHM
PPVCC_CPU_PH3=2.1OHM
PPVCC_CPU_PH2=1.9OHM
PPVCC_CPU_PH1=1.9OHM
PPVCCGT_CPU_PH2=4.7OHM
PPVCCGT_CPU_PH1=4.7OHM

DID I POST CORRECTLY

[mon2]

Low voltage rails will feature low resistance to ground by design. To me, the resistance check looks ok.

With no power to the board, measure the resistance from PPBUS_G3H to each inductor on the board.

Post any measurement that is low in value which means the high side mosfet has leaked.

[Arshad alam4659]

OK SHOP IS CLOSING TIME I WILL UPDATE TOMORROW THANKS

[mon2]

I believe that you will be missing the PP1V8_S5 rail? Facing a similar issue on an iMAC 2017.

Remove all power. Meter in DIODE mode. Red meter probe, yes red to ground. Black meter probe to the point to test.

Measure the PP1V8_S5 rail using DIODE mode. Post the measurement. We are checking if there is a possible shorted part on this rail.

More...see here:

A1989 (820-00850-A) - S5 rails missing : r/mobilerepair (reddit.com)

Your case may be the same - corrupt T2 firmware. Somewhere on this forum are dumps of the T2 eeprom that you can consider to review. Backup your image (just in case) -> apply the dump for your machine from the forum and test again.

Download the dumps from post # 17:

BY-U301 software and usb rom files requested - Badcaps

Continue to post your progress.

[Arshad alam4659]

Low voltage rails will feature low resistance to ground by design. To me, the resistance check looks ok.

With no power to the board, measure the resistance from PPBUS_G3H to each inductor on the board.

Post any measurement that is low in value which means the high side mosfet has leaked.

no beep inductor with ppbus_g3h

[Arshad alam4659]

I believe that you will be missing the PP1V8_S5 rail? Facing a similar issue on an iMAC 2017.

Remove all power. Meter in DIODE mode. Red meter probe, yes red to ground. Black meter probe to the point to test.

Measure the PP1V8_S5 rail using DIODE mode. Post the measurement. We are checking if there is a possible shorted part on this rail.

More...see here:

A1989 (820-00850-A) - S5 rails missing : r/mobilerepair (reddit.com)

Your case may be the same - corrupt T2 firmware. Somewhere on this forum are dumps of the T2 eeprom that you can consider to review. Backup your image (just in case) -> apply the dump for your machine from the forum and test again.

Download the dumps from post # 17:

BY-U301 software and usb rom files requested - Badcaps

Continue to post your progress.

diode mode
PP1V8_S5=0.345
volt
PP1V8_S5=0v

[Arshad alam4659]

I believe that you will be missing the PP1V8_S5 rail? Facing a similar issue on an iMAC 2017.

Remove all power. Meter in DIODE mode. Red meter probe, yes red to ground. Black meter probe to the point to test.

Measure the PP1V8_S5 rail using DIODE mode. Post the measurement. We are checking if there is a possible shorted part on this rail.

More...see here:

A1989 (820-00850-A) - S5 rails missing : r/mobilerepair (reddit.com)

Your case may be the same - corrupt T2 firmware. Somewhere on this forum are dumps of the T2 eeprom that you can consider to review. Backup your image (just in case) -> apply the dump for your machine from the forum and test again.

Download the dumps from post # 17:

BY-U301 software and usb rom files requested - Badcaps

Continue to post your progress.

i have no programmer U301
I HAVE SAME board 820-01814-a can i swap this chip working board

[Arshad alam4659]

can this be done by doing dfu mode

[mon2]

Yes, can be restored with DFU.

Yes, can be swapped with a known good chip.

[Arshad alam4659]

Yes, can be restored with DFU.

Yes, can be swapped with a known good chip.

not working 5v stuck

[Arshad alam4659]

and again swapped with original but also stuck in 5 vlt how