820-3787 Wont charge when need more power.

[ajdoc]

Hi

Got 820-3787. No liquid.
Client left with us as dead. No light on charger.
DC IN board blown, replaced and same story.
Replaced ISL its back to life but it charge battery only when Mac is turned off or when system is running its idle.
When some aps are opened which need some performance from Mac then is stop charging and % of battery going down with charger plugged in.

Same story with another ISL and with new battery.

R7151, R7152, R7122, R7121, R5380, R5381showing correct resIstance

Resistance in U7100:
Pin 27/28 21.5 Ohm
Pin 17/18 3.2 Ohm

Any ideas?

 

[ajdoc]

No Title

 

[JohnB8812]

Voltage on PPBUS from the charger only and then with the battery and charger?

 

[ajdoc]

Charger only PPBUS got 12.50V
Charger and battery PPBUS got 11.45V

 

[dukefawks]

Q7180 suspect.

 

[ajdoc]

Still same issue

 

[dukefawks]

Charger 85W and recognized as such in OSX?

 

[ajdoc]

No Title

Yes

 

[dukefawks]

Is this a known good charger, try another one even if it is a 60W.

Other than that check R7105 and soldering on U7100.

 

[ajdoc]

R7105 is fine with 20 Ohms
Soldering on U7100 looks good and all pads got connection with components.

Same issue with three genuine 85W charger.

 

[dukefawks]

Boot it up with battery and then disconnect it. See what PPBUS does when you load the system, see if it stays at 12.5V

 

[ajdoc]

System loaded with charger and battery PPBUS got 12.18V
Battery disconnected and PPBUS got 12.87V

 

[dukefawks]

PPBUS is too high. Q7130/35 are suspect. Double check resistance between 17/18 and 27/28 too.

 

[ajdoc]

27/28 21.3 Ohm
17/18 3.1 Ohm

I did not replaced Q7130/35 because from some reason board wont boot anymore.
ISL getting VERY hot within a second. Changed twice and same issue.

Do you still recommend to replace Q7130/35.

At the begging when DC-IN board was replaced ISL was very hot as well, but then I just replaced and board was working but not charging.
Now is same issue but new ISL wont help.

 

[dukefawks]

Change Q7130/35 and the ISL all together. ISL kills the FETS and the FETS kill the ISL so replace them all in 1 go.

 

[ajdoc]

Replaced Q7130/35 and the ISL and was working again.
Was even charging during GPU stress test and % was going up, but when I connected clients charger it stop charging during stress test.
I checked charger and its genuine 85W charger.

Do you think charger can kill Q7130/35 and the ISL?

 

[dukefawks]

Unlikely but possible. Is it a Chinese garbage charger? Keep in mind that these machines may not charge during 100% CPU/GPU load. The percentage should not go down though.