A1708 820-00840-A 20V -0000A no power

[mrwab]

HELLO EVERYONE
I´have MacBook pro 13 A1708 motherboard modele 820-00840 first come with short on ppbus g3h i found a shorted mosfet and replaced with a new one the voltage is come back 13V but in coil l7030 no 13V I need a help to diagnostic and fix this mac
thank you

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

1) Remove all power. Meter in resistance mode. Check the resistance to ground of fuse F7000, pin # 2 = PPBUS_G3H.

Post the measurement and scale used on your meter.

2) Remove fuse F7000. Power up again (using only the adapter) and measure the voltage @ F7000, pin # 1 pad on the PCB.

Post the voltage measurement for PPBUS_G3H (before the fuse and without a load).

What is the reading ? Must have proper PPBUS_G3H to continue.

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

[QUOTE=mon2;1138184]1) Remove all power. Meter in resistance mode. Check the resistance to ground of fuse F7000, pin # 2 = PPBUS_G3H.

Post the measurement and scale used on your meter.
i test in resistance mode i found 10mohm I have multimeter autorange

2) Remove fuse F7000. Power up again (using only the adapter) and measure the voltage @ F7000, pin # 1 pad on the PCB.
i test 13v on booth side of f7000 without remove it

Post the voltage measurement for PPBUS_G3H (before the fuse and without a load).

PPBUS_G3H is avilable in f7000 but not on l7030

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

PPBUS_G3H is avilable in f7000 but not on l7030

What is the exact voltage of PPBUS_G3H ?

Since you have a voltage @ PPBUS_G3H, L7030 is ok and working. Do not worry about this inductor. The mosfets and inductor are working as a BOOST regulator to accept 5 volts from the Type C power adapter to generate this higher voltage.

When the logic board negotiates 20V at the power adapter, then the ISL9239 will function as a BUCK regulator (high input voltage; low output voltage).

What voltage is being selected for your power adapter ? Is it 5 vdc or 20 vdc ?

Do you have a USB-C meter to confirm the voltage and exact current being drawn by the logic board ?

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

What is the exact voltage of PPBUS_G3H ?
13v on f7000
usb-c meter start from 5v then go to 19v 0.000a

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

13v for PPBUS_G3H seems high to me.

Change the batteries of your multimeter and check again.

Are you using the official Apple Type C adapter ?

What are the voltage readings of the following ?

SMB_SMC_CHGR_SDA
SMB_SMC_CHGR_SCL

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

Smb_smc_chgr_sda
3v on booth side of resistor r5380 and r7836

smb_smc_chgr_scl
3v on booth side of resistor r5381

Are you using the official Apple Type C adapter ?
YES ORIGINAL CHARGER

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

Locate each coil on the logic board. Meter in DC volts mode (20V is ok).

Measure the voltage to ground of each coil. Report any low / zero volt coil and its location.

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

all coil have 0v only coil l6995 have 3.42
and diod d6905
pin
1 13v
2 20v
3 20v
r6905 have 13v on boot side
and f3000 have 20v

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

Ok.

Remove all power. Meter in resistance mode (use lowest scale).

For each coil with 0V, check the resistance to ground. If the meter reports '1' = under limit, then switch to the next higher resistance scale on your meter.

Checking if you have a low resistance = bad caps or a short. Some rails, like the low voltage for the CPU are naturally low in resistance but post your results if you see a low reading.

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

ppvccio_s0g l7960 40ohm
pp1v2_s3_reg l8030 220ohm
ppvccpch_s5G l7900 72ohm
PP1V_S5G_REG l8060 95ohm
PPVCCSA_S0G_R l7370 007.0 ohm
PPVCCCPU_S0G_ l7210/l7220 005.5coil
PPVCCGT_S0G_ l7410/20/30have low resistance 4ohm

all other coil have high resistance on kohm

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

Any help friends
i have question why i dont have volt on coil l7030 but i have it f7000?
And no also standby voltages no 3v

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

Each such coil (inductor) is attached to a high side and low side mosfet. These mosfets are switching at high frequency on / off. Respectively, your multimeter should be capable of monitoring the switching rail. Unless the multimeter is of a high quality, the switching voltage will be missed by the test equipment.

If you have an oscilloscope, attach that tool's red probe onto the coil and black to ground. Then you should see a waveform that will be pulsing high voltage to low voltage.

A multimeter is not the proper tool to capture a high speed switching signal.

BTW: Digital scopes are quite affordable these days. We picked up a 200 MHz scope (refurbished) @ $200 USD from the factory. With full warranty.

[mrwab]

Re: A1708 820-00840-A 20V -0000A no power

how i can fixe this issue my friends please help me

[huseyinn]

Re: A1708 820-00840-A 20V -0000A no power

hi do you fix this problem?
i have same problem if you fix please help me thank you

[mon2]

Re: A1708 820-00840-A 20V -0000A no power

Measure the voltage to ground of the following:

SMBUS_BATT_SDA
SMBUS_BATT_SCL
PPBUS_G3H