820-00850 Dead

[Instafixx]

Hello Guys,
Namaste !

I have a macbook 820-00850 which is not switching on.
PPBUS_G3H is 0 Volts.

Checked everywhere via the schematics but could not find any short. Kindly help.

If we remove Fuse F7000, the Voltage of PPVBAT_G3H_CHGR_REG goes to 20V otherwise its also 0V

[mon2]

Re: 820-00850 Dead

With Fuse F7000 removed -> meter in resistance mode -> measure the resistance to ground of F7000, pin # 1 and then pin # 2 to ground.

Post each measurement.

There must be a load condition that is causing the PPBUS_G3H to be disabled when the fuse is installed.

[Instafixx]

Re: 820-00850 Dead

With Fuse F7000 removed -> meter in resistance mode -> measure the resistance to ground of F7000, pin # 1 and then pin # 2 to ground.

Post each measurement.

There must be a load condition that is causing the PPBUS_G3H to be disabled when the fuse is installed.

Meter set to 2K.

F700 #1 496
F700 #2 83

[mon2]

Re: 820-00850 Dead

Pin #2 of F7000 is with a low resistance.

With F7000 removed, power up.

What voltage do you read at the pcb pad for F7000, pin #1? You are checking if the ISL chip and power supply are working with no load.

Do you have a thermal camera? Do you have an adjustable dc power supply?

[Instafixx]

Re: 820-00850 Dead

Pin #2 of F7000 is with a low resistance.

With F7000 removed, power up.

What voltage do you read at the pcb pad for F7000, pin #1? You are checking if the ISL chip and power supply are working with no load.

Do you have a thermal camera? Do you have an adjustable dc power supply?

Board Removed (All Flex Open).
Connected to charger
Voltage at F7000 #1 is 12 Volts

Dont have thermal camera.

Have a Adjustable DC power Supply

[mon2]

Re: 820-00850 Dead

Some part is causing this low resistance to ground on the consumer side of this power rail.

Do inspect around for any visible signs of corrosion or liquid damage. That should be repaired if found. Use IPA to clean up such areas.

The PPBUS_G3H rail travels throughout the logic board.

With meter in resistance mode, still with no power. Proceed to measure the resistance to ground of each coil (inductor). Make a note of the coil(s) with a low resistance to ground.

[Instafixx]

Re: 820-00850 Dead

Some part is causing this low resistance to ground on the consumer side of this power rail.

Do inspect around for any visible signs of corrosion or liquid damage. That should be repaired if found. Use IPA to clean up such areas.

The PPBUS_G3H rail travels throughout the logic board.

With meter in resistance mode, still with no power. Proceed to measure the resistance to ground of each coil (inductor). Make a note of the coil(s) with a low resistance to ground.

Hi,
Can you name a few coils please?

[mon2]

Re: 820-00850 Dead

See attached. The coils will be the rather large 2 legged part and often grey in color. Attached are 4 examples on your logic board.

Each coil (aka inductor) is linked to a local power supply IC.