Macbook Pro A1708 820-00840 no power

[khanc0724]

Hi everyone! So my wife attempted to swap out her macbook battery and after she was done the laptop would not turn on. I tried powering on from just the charger and nothing. The battery is good. This is what I have right now after some troubleshooting.

Only taking 5V .2 AMPS
PP3V3-G3H is missing
I have followed the boot sequence and I have good voltages up until I get to PM_EN_P3V3_G3H, the voltage drops of from 5.1v to 4.2v. After that all voltages are in the boot sequence are 0.
I checked caps and I don't see anything. I tried using the thermal gun and no hot spots.
I did find D6905 input voltage to be 5.2 but output drops to 3.6 from.
From my understanding the 3.3V G3HOT SUPPLY (U6990) will not turn on unless there is 5v input present from D6905.

Could the problem lie with the diode? Any ideas or what else to check?
Thank you!

[reformatt]

Battery is glued, good chance she tried to pry it out with a screwdriver and levered it against the board or damaged the trackpad.

I would first remove the board from the chassis and inspect for pry damage and knocked off components. A dislodged 0201 resistor can be hard to spot without a microscope. 820-00840 boards should run outside the chassis without anything connected other than USB-C. PP3V3_G3H enable is from U7000, should be high to U6990 pin 10. Output voltage to D6905 will only be 5V without battery. All power voltages from USB-C will be 5V initially till the G3H rails come up and the CD3215's negotiate 20V.

[Stephen]

This seems like the battery was removed improperly as stated above. These boards easily communicate 20Volts without the battery, so something tells me the board got damaged, test the board without the battery connected and see what it says, if you get 20volts without the battery, then the battery is the culprit and you need to replace it.

[khanc0724]

Battery is glued, good chance she tried to pry it out with a screwdriver and levered it against the board or damaged the trackpad.

I would first remove the board from the chassis and inspect for pry damage and knocked off components. A dislodged 0201 resistor can be hard to spot without a microscope. 820-00840 boards should run outside the chassis without anything connected other than USB-C. PP3V3_G3H enable is from U7000, should be high to U6990 pin 10. Output voltage to D6905 will only be 5V without battery. All power voltages from USB-C will be 5V initially till the G3H rails come up and the CD3215's negotiate 20V.

I can't find a R0201 on the schematic. My output voltage from D6905 is only 3.3v with 5.05v going in. Voltage at pin 10 of 6990 is 4.12v.

[khanc0724]

This seems like the battery was removed improperly as stated above. These boards easily communicate 20Volts without the battery, so something tells me the board got damaged, test the board without the battery connected and see what it says, if you get 20volts without the battery, then the battery is the culprit and you need to replace it.

I did a close inspection of the board but I do not see any physical damage. Not even scratches or nicks. I did notice that when checking the D6905 for resistance, with meter set at 2K I am getting 1.8K from pin 2 to 3 and 190 from pin 1 to 3.

[mon2]

Flux and remove D6905 carefully off the board. Test again without this part. Be sure there are no solder shorts after the part is removed.

[khanc0724]

Flux and remove D6905 carefully off the board. Test again without this part. Be sure there are no solder shorts after the part is removed.

Should I bridge the two pads from pin 2 to pin 3 and check for voltages again at U6990 and U7000

[reformatt]

I can't find a R0201 on the schematic. My output voltage from D6905 is only 3.3v with 5.05v going in. Voltage at pin 10 of 6990 is 4.12v.

0201 is a reference to the size of the component, not a component designator. I repaired a board recently that I bought for parts that had one of these resistors partly knocked off near the SMC. Board was otherwise dead, and that is all it was too.

You have the enable to U6990 so that's fine. D6905 is a dual Schottky diode, should be only .2V drop across it. You either have a defective diode or an excessive load. Check diode mode readings to ground on the input and output of U6990 (neg probe on test point, red probe on gnd). Openboardview data says it's 0.55 and 0.35 respectively.

[khanc0724]

0201 is a reference to the size of the component, not a component designator. I repaired a board recently that I bought for parts that had one of these resistors partly knocked off near the SMC. Board was otherwise dead, and that is all it was too.

You have the enable to U6990 so that's fine. D6905 is a dual Schottky diode, should be only .2V drop across it. You either have a defective diode or an excessive load. Check diode mode readings to ground on the input and output of U6990 (neg probe on test point, red probe on gnd). Openboardview data says it's 0.55 and 0.35 respectively.

Just to make sure I did it right. With power removed, I checked pin 2 on U6990 to ground and pin 9 to ground in diode mode. I got .66 and .72 respectively, whatever that means. Nowhere close to .55 and .35.

[reformatt]

Just to make sure I did it right. With power removed, I checked pin 2 on U6990 to ground and pin 9 to ground in diode mode. I got 664 and 727 respectively, whatever that means. Nowhere close to .55 and .35.

Output is the coil L6995 (pin 3). Seems input to the chip isn't shorted so it's looking like D6905 is no good. Should read .2V in diode mode between pins 1-3 or 2-3 and open circuit the other way.

[khanc0724]

Output is the coil L6995 (pin 3). Seems input to the chip isn't shorted so it's looking like D6905 is no good. Should read .2V in diode mode between pins 1-3 or 2-3 and open circuit the other way.

I'm leaning towards that same conclusion. D6905 between pin 2-3 is 1.8v and 1-3 is .22v. I ordered some BAT30CWFILM diodes, hopefully it will fix the issue.

[mon2]

No. The replacement parts are not suitable to replace D6905. As noted earlier, flux and remove this part. Test without this part on the board. Arrow has the exact replacement and can confirm if others like Digikey stock the same.

Follow this thread - take a while to repair:

https://www.badcaps.net/forum/troubl...4ma-on-charger

[reformatt]

No he has the right one. Seems to me you are confusing D6905 and D6950?

[mon2]

Yes, indeed. My bad. Note to myself..more beauty sleep. Just ignore my comments.

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of each pin on D6905. Post the measurements.

[khanc0724]

Remove all power. Meter in resistance mode. Measure the resistance to ground of each pin on D6905. Post the measurements.

PIN 1, 2, and 3 are all OL. I removed D6905 and I am still only getting 3.27v on pin 3 with 5.2v on pin 2. Should there even be any power on pin 3 with the D6905 removed?

[mon2]

Should there even be any power on pin 3 with the D6905 removed?

No. Something is wrong here. This dual common cathode diode is feeding the higher of the 2 input voltages to the input of the regulator @ U6990. It appears that U6990 is defective if you are measuring a voltage on this 'floating' input pin.

While you have the diode D6905 removed, test this diode in DIODE mode of your meter.

Red meter probe on pin # 1, black meter probe on pin # 3 - the meter should conduct. Reverse the meter leads and the meter should block = OL.

Repeat with pin # 2 and pin # 3. Same expected results if this diode is not defective. Share the meter measurements in diode mode.

If you have 5v2 as an input to D6905, the output of this dual diode at pin #3 should be ~0v3 to 0v6 lower than the input voltage. Anything lower will most likely mean that you have an excessive load on the line as in a shorted capacitor, etc.

[khanc0724]

No. Something is wrong here. This dual common cathode diode is feeding the higher of the 2 input voltages to the input of the regulator @ U6990. It appears that U6990 is defective if you are measuring a voltage on this 'floating' input pin.

While you have the diode D6905 removed, test this diode in DIODE mode of your meter.

Red meter probe on pin # 1, black meter probe on pin # 3 - the meter should conduct. Reverse the meter leads and the meter should block = OL.

Repeat with pin # 2 and pin # 3. Same expected results if this diode is not defective. Share the meter measurements in diode mode.

If you have 5v2 as an input to D6905, the output of this dual diode at pin #3 should be ~0v3 to 0v6 lower than the input voltage. Anything lower will most likely mean that you have an excessive load on the line as in a shorted capacitor, etc.

Ok, I tested D6905:

Pin 1 - 3 = .22v
Pin 2 - 3 = OL

Reverse = OL on both pins

[khanc0724]

I tested the caps again and C6989, C6988, C6996, C6997, C6998, C6995 show shorted to ground. I'm guessing one of them is causing the others to short out too? Any advice on how to test? I am also getting continuity to ground on both pins on L6995, something to check?

Voltage on L6995 pin 1 and 2 is 0.3V
Resistance to ground on L6995 from pin 2 is 11.8 ohms.

[mon2]

Pin 1 - 3 = .22v
Pin 2 - 3 = OL

1-3 is ok
2-3 is not ok if you have red on pin # 2; black on pin #3. You should have a similar measurement of .22v like 1-3.

This diode is defective.

Carefully flux and remove resistor @ R6999. This action will isolate the producer and consumer sides of the power supply. Then measure the resistance again on L6995 - either side. Do you still see a low resistance of 11R8 ohms to ground? If yes, the issue is on the producer (regulator) side of the circuit. If not, the short is on the consumer (downstream / load) side of the circuit.

Confirm the details.