Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

[platinumsteel]

Hi guys i have a 820-00840 that works fine and boots up as long a battery is not connected. I initially thought it was a bad battery so i went ahead and bought a new battery for it and slapped it in yesterday and realize that the same fault exists. When i screw in the battery and connect the little battery strip and i press the power button it will not power on.At that time If i connect the charger i get fan spin for 10 seconds then stops but the machine won't power on.If i disconnect the little battery strip and re-plug the charger the machine boots as normal.It's not the battery connector strip because i tested it on another identical machine i no longer have now so the connector is good.I have 2x connectors. With battery alone fully connected i get 12.78v on PPBUS_G3H . Also when i first plugged in the new battery i was getting 1.875 amp draw so I assume the battery charges like normal.Not sure what to check so am hoping you guys can guide me further thanks.

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Hi. Long time to hear

Remove all power. Meter in resistance mode.

Start with reviewing the details of the battery mosfet @ Q7065.

Check the resistance across the mosfet pins to see if it is leaky.

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. If you have a low reading, the mosfet is defective and must be replaced.

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Thanks a lot for your help always appreciated. I have posted the resistance readings below.

source (1-2-3) & drain (5-6-7-8) 08.40k

source (1-2-3) & gate (4) 08.35M

gate (4) & drain (5-6-7-8) 08.64M

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

source (1-2-3) & drain (5-6-7-8) 08.40k

Ouch. Can you confirm that this is indeed 8k4 ohms ? That is very low for a mosfet.

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Yes it's confirmed. It's indeed 8.4K . Have 3 donor boards laying around and well they are measuring close to that value one of them measuring 9.5K so not certain at the moment. I have no working boards atm. I would of changed it anyway but am a little reluctant cause on both sides are connectors kinda close.lol But am willing to do anything at this point since the sale of this machine is to purchase my first Thermal camera. lol So really need the help to solve this one.

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

If others are measuring this value or close to, wait for a few more checks. The readings may be low due to the mosfet being in-circuit on the logic board.

1) is the logic board able to power up with only the battery?

2) remove the battery, apply the power adapter.

Review the voltage to ground on Q7065:

source pins (1-2-3)

gate pin (4)

drain pins (5-6-7-8)

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

1 . No with only the battery plugged in it never powers on.I measured PPBUS_G3H with battery connected and i get 12.78v
Voltages are as follows.
Source =13.07v
Gate =13.06v
Drain =12.90v

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Remove all power. Check the resistance across the other mosfet pins that are linked to the ppbus_g3h rail.

Checking to see if they may be leaking.

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

More thoughts...

The battery is unable to power the logic board since the battery mosfet is technically off. With P-channel mosfets, the gate must be lower than the voltage being passed between source and drain pins.

The voltage that you do see on ppbus_g3h with only the battery is due to the internal forward bias of the diode in the mosfet.

Measure the voltage to ground of each pin on the battery connector. Specifically interested in the SCL and SDA pins.

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

My friend With battery connected I get on pins 2 and 3 of battery connector which is SMBUS_SMC_5_G3H_SCL/SDA i get 3.1v on both SDA and SDL pins

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

My friend the worst thing happened just now.All i did was check a few resistors on the sda/sdl lines and just connected back the battery and everything to take some more voltage measurements and guess what when i plugged the charger it turned on with battery connected. The machine would of never done this.It would not turn on with that battery connected. i swear i did not swap anything or change anything. Now machine appears to be working fine.With battery only when i press the power button it turns on.Works on battery as well.Turn on and shut down with battery.Also works and chargers with battery too.Battery is 100% right now.I hate these kind of weird faults they have a way of coming back to haunt you.I will run the machine for a week.And see how it goes.
And you were so right about the P-Channel Mosfet technically off.Cause now with battery alone connected these are the voltages to ground on the Mosfet Q7065
Source=12.72v
Drain 12.72V
Gate 4.85V
Do you think the Mosfet might be still faulty and just decided to randomly work properly? Think i should change it ? Cause i don't have a good feeling about this.I am scared the issue will come back.

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

okay my friend . I'm throwing in the towel on this one.Just as expected the weird issue is back. Think i will buy a replacement board and not bother trying to figure out this random issue. But thanks a lot for the help much appreciated as always. Learnt a good couple new things from you.

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Attach both battery and adapter. Perform a smc reset upon power up. Any difference?

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

See attached.

Remove the power adapter. Connect only the battery.

Meter in DC volts (20v or higher is ok).

Measure the voltage to ground on each point of this dual common cathode diode.

This diode is used to select the higher of the 2 power rails. Since the external adapter is removed, only the PPBUS_G3H side should be active. Need to confirm the voltage to ground of each leg.

It is possible that this diode @ D6905 is defective.

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

To test the diode in another way.

Remove all power. Meter in diode mode.

Red probe to the back side of the diode (anode), ppbus_g3h feed. Black to the cathode of the diode.

What is the measurement? Reverse the leads. What is the measurement?

Now move the red meter lead to the other anode pin, charger input feed. What is the measurement?

Reverse the leads. What is the measurement?

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

To test the diode in another way.

Remove all power. Meter in diode mode.

Red probe to the back side of the diode (anode), ppbus_g3h feed. Black to the cathode of the diode.

What is the measurement? Reverse the leads. What is the measurement?

Now move the red meter lead to the other anode pin, charger input feed. What is the measurement?

Reverse the leads. What is the measurement?

0.203v on both the two separate measurements u requested
Reverse leads says 0.L

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

With only the battery attached, check to see if you have the 3v42 power rail that follows this d6905 diode.

What is the voltage to ground of this key rail?

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Okay so good thing i didn't stick the battery down yet. so i have the new battery out of the chasis with battery and board alone connected ok..
D6905
Pin 1 = 12.47v
Pin 2 = 0v
Pin 3 = 12.68v

U6990 Pin 3 = 3.4v
Pin 10 = 5.166V

isn't pin 10 which is the enable for U6990 supposed to be 3.3v ?

[mon2]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

So far ok. I think the voltage readings on pin # 1 and pin # 3 of d6905 are maybe reversed?

Pin #1 should be higher -> then the diode will lower the voltage by a small amount since it is not a piece of wire and there is a voltage drop onto pin #3.

Otherwise ok.

Remove all power.

Meter in resistance mode. Confirm the resistance from F7000, pin #1 to C7020, pin # 1. What is the measurement? It must be ~1 ohms.

Repeat with C7065 (or another good test point), pin # 1 and to C7020, pin #2.

What is the measurement? It must be again ~1 ohms.

Confirm each. These are the very critical current sense loop circuits. The engineer who designed this circuit is expecting these values and if they do not match or there is a trace break, the ISL will think the battery is in trouble and will power OFF the battery mosfet. That is, will leave the GATE voltage to float which means the P-channel mosfet will be forced OFF, as a default.

Love snow shoveling - only counting cars beats the fun. Used muscles I did not know I had.

[platinumsteel]

Re: Macbook Pro 13'' 2017 A1708 Won't power on with battery connected.

Okay so am like so ashamed right now. mon2 you will kill me for this. While i had it out the chasis i plugged adaptor with battery connected and i realized it started normally. So i put it back into the chasis and left the screen connector out. And it powers on and works like normal with battery or battery plus charger but the screen connector has to be unplugged. I do get external display.(I always make sure no power to board when dealing with screen connector for safety in case you are wondering lol}.
But i have no problems with the screen connected and charger alone.Which is why i could of never suspected the screen.But it's not a bad screen.I have been using this test screen on all my other 3x A1708 and it never did this.Just last month i had this screen using properly in an A1706 i gave to my cousin 2 months ago.The screen connector is in perfect condition under the microscope. i know without a doubt the screen isn't faulty. This board has always been doing this issue from day one i got it even with other screens.
So this issue has gotten more difficult cause right now if i have the battery connected it will not power on.If i unplug screen connector it will power on.If i disconnect battery and use only charger machine will auto power on and boot like normal with picture.Please advise further what i can do thanks.