Macbook a1707 820-00281 Battery no Power

[mon2]

J6951 is the BMS (SMBUS interfaced) cable connector for the battery pack. Share a clear pic of this connector and also the bare contacts on the flex cable that mates with this connector. Be sure the contacts are clean and not cross shorting. Be sure the # of contacts of this BMS cable match the expected contacts on the J6951 connector. Have done this in error in the past where the pin pitch was different from one macbook model to another but was with a trackpad cable. Same overall width of the flex but different # of contacts and had the same fault of not booting everytime the (wrong) flex cable was mated.

Although does not appear to be related, do check the dual diode @ D6902. Confirm that it is not leaky.

[leonemax81]

I attach some photos

[leonemax81]

the battery cable is clean and matches the motherboard connector pins.

[mon2]

With no power to the board and the battery disconnected but keep this SMBUS flex attached from the battery.

Perform diode mode testing of each pin on the flex cable.

Would you have access to the original battery that was used on this macbook? Still concerned about the battery BMS and the related SMBUS commands that may or may not be present on the batteries you are testing. Even if the battery packs are working on other macbooks, are those macbooks also A1707s? If not, seek out one from Amazon for testing.

[leonemax81]

yes the batteries are compatible with a1707 models and work on other macbooks, I think at this point it's the smc chip.

ASMARK Batteria MacBook Pro A1707 per 15 pollici 2016-2017 A1820 Battery : Amazon.it: Informatica

[leonemax81]

diode mode:

SMBUS_SMC_5_G3_SCL measures 0.471v.
SMBUS_SMC_5_G3_SDA measures 0.471v.

[leonemax81]

that flat cable does not emit voltage but only data signal that goes to the SMC chip, so I think the problem is the SMC chip.

[mon2]

Perhaps. ASMARK is ok with us - we have used them a few times as well. Believe they also offer with a 2 year warranty. Note that the SMC communicates with the BMS board using the same SMBUS lines so you are suspecting corrupted SMC firmware?

re: your last post.

BMS is a slave SMBUS / I2C node. The bus master will be the SMC but we know that is working since PPBUS_G3H is escalated as it should using SMBUS communication. Not sure of what to say here but if you are comfortable, consider to test with another SMC IC. Or at least reflow it. Weird that the board chokes when you mate only this flex cable. The SMC, as the bus master, will send out the commands to ping the BMS. Then the BMS must respond.

BTW - what if you do the same on the working board? Remove the battery screw but attach the flex cable only. Does that board boot or power cycles?

[leonemax81]

as shown in the photo, I don't insert the screw, I just connect the black flat battery cable without inserting the screw and the MacBook doesn't turn on, what do you suggest I change the SMC chip?

[mon2]

Understood. Just asking if the other macbook boots ok with a similar setup. Remove the battery screw but connect the flex. Does the other macbook power cycle or boots ok? I suppose you can try to replace the SMC or wait on other comments. Not much is left here to test. Very weird.

[leonemax81]

the battery on the other macbook works fine, yes the defect is very strange, I have never had a similar defect, I don't know what to think.

[leonemax81]

updates, SMC chip replacement without solution usual defect, I tried to insert the battery flat cable with the macbook on, as soon as I insert the flat I hear the sound, the battery is also recognized but does not charge, as soon as I unplug the charger the defect returns.

[leonemax81]

I also replaced the J6951 connector, without success.

[mon2]

But..now you can power up with the external adapter AND the battery with 20V PD contract + battery is detected. Just not charging. Correct?

[leonemax81]

no, the defect is the same, I inserted the battery cable when the macbook was on and started.

[mon2]

I hear the sound

Which sound? The charging sound from the speakers? You are hot plugging in the flex after the macbook is on and the battery is detected as shown? But straps the booting process if the flex is on before power on?

Check the presence of the pull-up resistors on this common SMBUS lines.

[leonemax81]

exactly its charging when I insert the flat cable with the macbook on, I also checked those two resistors and they are 2.0k

[mon2]

This board needs an exorcism.

Remove all power. Meter in resistance mode. Remove the flex cable. Measure the resistance to the pull-up voltage rail for each leg - the

SMBUS_SMC_5_G3_SDA
SMBUS_SMC_5_G3_SCL

The resistance should be close to the pull-up resistor values.

Repeat with the flex cable mated to the logic board. Any differences?

Also, what is the voltage to ground of SYS_DETECT_L? This signal should be pulled low through the pull-down resistor @ R6950. Confirm at the contact of the flex as well.

[leonemax81]

with cable disconnected:
SMBUS_SMC_5_G3_SDA resistance 2.0k
SMBUS_SMC_5_G3_SCL resistance 2.0k

while with cable connected SMBUS_SMC_5_G3_SDA SMBUS_SMC_5_G3_SCL the resistors change a little in value.

on the R6950 resistor I have no voltage, neither with the cable disconnected nor any voltage with the cable connected.

[mon2]

This must be an in-rush case which was cited by reformatt a while back. Unable to locate his thread.

Remove all power. Measure the resistance across C7023. We are confirming the full path resistance of the current sense loop at the input to the ISL buck / boost controller.