820-00281a power cycle with battery. slow 20v

[BoKKeR]

Just battery SMC bypass without charger does not work,

Battery with charger (and battery ribbon) SMC bypass. It starts, errors out first 1-2x, then it boots normally but I cant see the battery show up anywhere but this can be because of the bypass. If I disconnect the charger the battery holds the laptop alive.

I added the error below that I get before it launches.


I will test more later today

Edit: it works without charger only using battery in smc bypass
EDIT2: did a smc reset, it powered on without smc bypass and charger, sitting at 45%. Will have to test it more
edit3: it wont charge drawing 0.14a , unplugging made it turn off. And its back to power cycling

 

[BoKKeR]

Any idea? can all the batteries be bad? or the board?

 

[2informaticos]

The best thing is testing with "known good worling" battery.

If I correctly understood from your last post, the machine always start booting with battery alone?
It doesn't boot with charger alone, or charger and battery both connected?

 

[BoKKeR]

The machine always boots with charger alone
Does not boot with battery only
Only boots with battery and charger in smc bypass mode

 

[2informaticos]

Check CHGR_A/BMON levels, with both charger and battery connected.

 

[BoKKeR]

The charger cycles between trying to switch from 5v to 12v with battery. CHGR_A/BMON are 0v.

I found something accidentally,
1. starting MacBook without battery ribbon with charger.
2. I turn on the laptop.
3. I connect the battery ribbon (while it's starting) and the battery reports the right charge percentage and charges at 3A 20v.
4. I disconnect the charger.
5. laptop keeps alive
6. connect the charger back.
7. Laptop dies.

I measured CHGR_AMON was 0.5v in this case and BMON 0v.

 

[2informaticos]

Start with charger and battery properly connected in SMC bypass mode.
Then post CHGR_A/BMON levels.
Also check SMC_DCIN/PBUS_VSENSE.

 

[BoKKeR]

following values with SMC bypass with battery and charger:

CHGR_AMON 0.008v
CHGR_BMON 0.001V
SMC_DCIN_ISENSE 0V
SMC_PBUS_VSENSE 2.2V

 

[2informaticos]

SMC_DCIN_VSENSE level?

 

[BoKKeR]

that was a challenge to measure
SMC_DCIN_VSENSE 2.65v,

 

[2informaticos]

That value is correct.
Post now SMC_DCIN/BMON_ISENSE.

BTW, you've posted to CHGR_AMON values, with big difference; what happened?

 

[BoKKeR]

In smc bypass mode with charger and battery connected and turned on 20v coming in:

SMC_BMON_ISENSE 0.003v
SMC_DCIN_ISENSE 0.005v
CHGR_AMON 0.052v
CHGR_BMON 0.000v

It was 0.05 but I wrote 0.5 before, my bad :/

 

[2informaticos]

None of these values are strange.
However there should be a problem with one (at least) SMC sensor, as the machine starts in SMC bypass mode.
Check first AVREF_SMC at C5021.

 

[BoKKeR]

PP3V0_S5_AVREF_SMC is solid 3V on C5021 and C5020

 

[2informaticos]

Check Power Sensors from pages 50-53.

 

[BoKKeR]

PP3V3_S0_LEFT = 0v
PP3V3_S4SW_SNS = 0v
EADC1_TBT_T_ISENSE 0v
EADC1_PP5V_T139_ISENSE = 0v
EADC1_TBT_X_ISENSE = 0v

Are they supposed to be high when indicating fault?

 

[2informaticos]

Some sensors are enabled only when board is on.
Especially ISENSE type, as S4-0 voltages too.

If the machine tries to start in normal mode (at least pulsing voltages) and only starts in SMC bypass mode, then should check all sensors in SMC bypass mode.

 

[BoKKeR]

Could you help which sensor to check? I only found those 5 I mentioned above.

 

[2informaticos]

Check pages 51-53...