820-4924 with orange juice LD ---> semi repaired? Empty battery shows on screen.

[george-a]

Hi guys,

This one looked like it took a dive in an orange juice bucket. I UC it and then there was no green light. I looked around and SMC_BC_ACOK was missing while PP3V42_3GH was ok. The problem was U7100 which I replaced and voila there is green light and the CPU gets hot.

I now half assemble the laptop to check if there is image and here is what happens. When I plug the magsafe in there are all voltages present on the motherboard at all coils and the screen shows an empty battery with a bolt (like in iPhones) for few secs - no fan spine - and it then turns off (along with all voltages except S5 voltages and PPBUS_G3H at 12.5 to 12.6V). That happens every time I reconnect the magsafe.

Has this macbook turned into an iPhone? Should I hook a sim card? Other ideas?

br,
george

 

[dukefawks]

What is PPBUS voltage with battery connected?

 

[george-a]

12.2V to 12.4V (doesn't look thrilling)

EDIT: 12.4V most of the time... dives to 12.3V rarely to 12.2V.

 

[dukefawks]

Bad battery is my guess.

 

[george-a]

but it shows the battery symbol without the battery connected, too... and then all voltages turn off.

 

[2informaticos]

Does it stay on without battery?
If OSX shows battery symbol seems that SMC "chats" with it at least.
Peel the plastic and look at battery electronic circuits.
If you see corrosion signs there, change it.

 

[george-a]

it should start without battery but even then it shows the empty battery symbol, when the magsafe is attached, and nothing else. If you press On/Off button SMC_ONOFF_L goes LOW but nothing else happens. Also the fan does not spin..

 

[george-a]

this symbol appears for a few secs - with or without battery - and the laptop turns off. No fan activity at all.

 

[dukefawks]

The fan never spins on these when cold. I believe some of these need a good battery to start. If green/orange light is OK and PPBUS is at 12.6V I still say your battery is dead.

 

[george-a]

so you suggest I need a good battery? shouldn't this model boot without the battery like the rest? Or maybe should I check battery communication to the SMC? Maybe there is an issue there? I will try tonight..

 

[2informaticos]

Be sure to use real 85W charger.
Check if PM_BATLOW_L is high.

 

[george-a]

So I did some measurements and I get:

1) 3.40V at R5381 (SMBUS_CHGR_SCL)
2) 0V ar R5380 (SMBUS_CHGR_SDA)
3) PM_BATLOW_L is low when the charger in attached (with battery connected) and remains low for the following seconds
4) CHGT_BGATE is HIGH at Q7155 and does not charge the battery - the output at the Drain is 2.3V

I also did a bit of SMC heating with flux.

you have the ball.

 

[dukefawks]

2) if this is the case then PPBUS without battery should be 12.3V, confirm this. If PPBUS is 12.56V the SMBUS is fine.

I still say the battery is fucked too.