820-2915-A Wont power on with battery connected

[beogeek]

Re: 820-2915-A Wont power on with battery connected

replaced Q7055
source 12.38
drain 12.38v
gate 5.384v

still same issue, fans spin up and then nothing

I've also placed back D6990 fyi

[mon2]

Re: 820-2915-A Wont power on with battery connected

Without power, post the resistance readings of the replacement Q7055 mosfet.

Then post the voltage of PPBUS_G3H with the battery.

Does the fan continue to run with the battery or just a brief on then off cycle if using only the battery?

[beogeek]

Re: 820-2915-A Wont power on with battery connected

Q7055
source (1-2-3) & drain (5-6-7-8) 28MΩ red probe on source, black on drain
source (1-2-3) & gate (4) 0Ω red probe on source, black on gate reversed probes 5.4MΩ
gate (4) & drain (5-6-7-8) 24MΩ red probe on gate, black on drain

PPBUS_G3H measured at R5400 R5410 12.38v

[mon2]

Re: 820-2915-A Wont power on with battery connected

source (1-2-3) & gate (4) 0Ω

This is not a good reading. This should not be a short. Can you confirm ?

Also confirm that soldering is ok on Q7055 and the related parts.

You can apply flux on the mosfet (Q7055) -> hot air it till the part is able to swim. Then nudge it with tweezers and the part should move and settle back naturally onto the SMD pads on the PCB.

Then check the resistance again for source & gate pins.

OR - did you mean to write "OL" (over limit) for this resistance reading ?

[beogeek]

Re: 820-2915-A Wont power on with battery connected

Sorry source (1-2-3) & gate (4) OL not 0ohms, yes checked it its soldered on well. 8.56MΩ when I reverse the probes

[beogeek]

Re: 820-2915-A Wont power on with battery connected

see check it

[mon2]

Re: 820-2915-A Wont power on with battery connected

Ok - now the Q7055 mosfet readings are good.

Confirm the voltage of PPBUS_G3H after the fan spin stops (use battery only).

Then check that the same voltage is present @ PPVIN_G3H_P3V42G3H. This is pin # 3 of D6990.

The battery should continue to create the PP3V42_G3H @ coil L6995, pin #2. Confirm this voltage as well after the fan stops the spin.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

PPBUS_G3H 12.38
@ PPVIN_G3H_P3V42G3H. This is pin # 3 of D6990: 3.354
PP3V42_G3H @ coil L6995, pin #2. 2.504

Now i do not get fan spin with just the battery connected, I only get slight fan spin if I connect the adapter. Even shorting the keyboard connector doesn't produce a slight fan spin with just battery connected.

[mon2]

Re: 820-2915-A Wont power on with battery connected

PPBUS_G3H 12.38

Good value.

@ PPVIN_G3H_P3V42G3H. This is pin # 3 of D6990: 3.354
PP3V42_G3H @ coil L6995, pin #2. 2.504

Both of these are bad values.

Check the voltage on pin # 1 again on D6990 diode. This is PPBUS_G3H and should match the voltage of 12v38. This voltage is going into D6990 but not leaving this dual diode.

Do you have a replacement for D6990 ?

If not, we can try a temp "hack" (will have to do it quickly before @Piernov reads this thread

[beogeek]

Re: 820-2915-A Wont power on with battery connected

pin # 1 again on D6990 diode 12.38v yes ive got a donor board, should I swap them?

[mon2]

Re: 820-2915-A Wont power on with battery connected

Yes, please do. The dual diode is not working correctly for this leg of the circuit.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

ok replaced the diode, reading is now 12.38v also L6995 is showing 3.475v on both sides. Now shorting the keyboard does produce fan spin but for a few seconds, like when the battery and power is connected.

[mon2]

Re: 820-2915-A Wont power on with battery connected

Good.

If you use only the power adapter, the logic board works properly and you can see the Apple logo, etc. ?

If you then use only the battery, you see the fan spin for a few seconds but then nothing ? After the fan turns OFF, confirm the voltage of PPBUS_G3H and PP3V42_G3H.

Both should remain to be normal values with only the battery.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

Yes boots fine without battery.

After the fan turns OFF
PPBUS_G3H 12.37
PP3V42_G3H 3.475

Both should remain to be normal values with only the battery. Correct.

[mon2]

Re: 820-2915-A Wont power on with battery connected

Now that PP3V42_G3H is restored with the battery only, check the voltage of D6950 again.

Post the readings.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

D6950 pin 1&2 3.463 pin3 0V

[mon2]

Re: 820-2915-A Wont power on with battery connected

Now the diode readings are correct.

1) Confirm that the SMBUS (same pins you just tested) are solid and reaching the physical connector for the battery. If the contacts are not solid to the battery, then the logic board cannot see the battery pack. Numerous transactions occur over these I2C (SMBUS) pins to extract parameters from the battery.

2) After the above - boot up WITH the power adapter & battery connected.

Does the MAC OS see the battery and report the number of charge cycles, etc. ? This will confirm that the SMBUS interconnect is OK.

3) Aside from the above, I think it will be best to replace the battery and test again. It appears that everything is in order now - aside from the actual SMBUS communication with the battery pack.

Post the details of the above testing. You are very close.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

Ok touched up the diode, tested it from the diode to the connector it has continuity from the diode to the battery connector.

Trying to boot with the battery still no go, will boot without it. With the battery connected the fans spin for a brief moment and then back to nothing.

[beogeek]

Re: 820-2915-A Wont power on with battery connected

I'll order the replacement battery and check it again when it arrives. Sheesh and everyone always complains that the SMC is difficult to replace, this was a nightmare hahah doubt I would have gotten to this stage without your help again. And now thinking back, I tripped up over Q7055, I didn't measure it correctly and then I ended up in a loop looking for the issue while it was staring me right in the face. I'll get that battery and see what it does when it arrives, I'll post back when it arrives. Thank you mon2 you've been a bloody life saver!

[mon2]

Re: 820-2915-A Wont power on with battery connected

No worries. Trying to throw out my 2 bits when I can..it is very much trial & error and hopefully will save someone some time in future readings.

Can you confirm that you are able to boot up if BOTH, the adapter & battery are connected ? If you can boot up normally, what does the MAC OS report for your battery ?

Very interested to know if the logic board can ping out the # of charge cycles, etc. out of the battery pack. This will confirm that the BMS inside the battery pack is OK.

Otherwise, I think what may be happening here is that the SMBUS communication is at fault with the actual battery pack. That is a hunch. The lines are open-drain and are now being pulled up to the 3v42 rail ok.

Perhaps the BMS module inside the battery pack is defective. A replacement known good battery is a good test for your case. Just be cautious from where you source your batteries as others have reported that there is a lot of garbage on the market. Not a bad idea to buy from Amazon or similar where you have a return policy if you do not love the battery.