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820-2879 works on battery but not on adapter

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sangolossyfon

Member
Hi I have a 2010 13' Unibody that will power on and run fine when a charged battery is connected but it does not run at all when just connected to the adapter nor does it charge the battery. Obviously this rules out G3H as having any problems and also the PP3V42_G3H does have 3.65 volts but still no light on the charger. There is an extremely faint green light actually but almost unnoticible. I have tried re-flowing the SMC with no luck.
Other voltages-
Charger outputs 18V to laptop and draws 3.5w from wall but green light still extremely faint
PPBUS_G3H does not get power when just charger plugged in
it gets about 11.8v when battery plugged in
when only charger plugged in-
SMC_BC_ACOK- 0.11v
SMC_BC_ACOK_VCC- 0v
SMC_ONEWIRE- 0v
Thanks for any help on next things to check!
 
2informaticos

2informaticos

Administrator
Staff member
Any history available?
Did you try known good DCIN board?

Test with fake (chinese) charger, or lab PSU and Magsafe 1 cable.
 
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sangolossyfon

Member
I don't know any history of the board but it doesn't have any water damage. The charger is 85w original apple and it works on other boards and has the full green light. If I were to test with PSU should I just set voltage to 18V and current to max and connect it to the board?
 
2informaticos

2informaticos

Administrator
Staff member
Original charger has an embedded processor.
If detects any leakage on the Mac's mainboard, will stop to deliver output voltage.
That's the reason I told you to test with fake charger; that one is not so "smart".
 
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sangolossyfon

Member
Tested with 18.5V on the lab PSU. Drew about 2.8watts but still did not boot when the poweron pads were connected nor did the wattage change at all.
 
2informaticos

2informaticos

Administrator
Staff member
You can't connect power directly on the board.
SMC requires One-Wire connection!
I told you to use a spare Magsafe 1 cable; even 45W is good enough.
 
2informaticos

2informaticos

Administrator
Staff member
Remove U7000 and check again.
If still short, then bad C7021/2; which I doubt.
If short gone, replace U7000.
 
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sangolossyfon

Member
Short was gone so I replaced U7000 with known working chip

charger showed green light for a few attempts but then went back to showing nothing, now a buzzing noice comes from U7000. Still draws 3 watts
however short on 19&20 is still gone

old next to new voltages on U7000 (new voltages on right- measured while making buzzing noise)
1- 16.2v to 17.5v
2- 14.3 to 18.3v
3- 4.24 to 4.37v
9- 0.08 to 0.03v
12- 3.64 to 3.8v
13- 3.64 to 3.8v
14- 0.11 to 3.55v
15- 0.10 to 0.05v
17- 0.13 to 0v
19- 0.14 to 5.7v
20- 0.14 to 5.7v
27- 0.34 to 18v

pin 17 is also shorted to ground. this short remains on the board even when I remove U7000 again. So not the fault of U7000.
none of the other pins with near 0v are shorted just pin 17
pin 18 is not shorted

BOTH CHARGER_CSO_R_P and R_N are shorted to ground

edit: ppbus_g3h is shorted to ground with U7000 being gone

should I inject voltage? with U7000 gone, green light actually works but obviously no boot

with f7040 removed short does not remain on g3h so this isolates it

edit: L7030 was shorted, will replace tomorrow
 
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2informaticos

2informaticos

Administrator
Staff member
"L7030 was shorted"
Do you mean between its pins?
What do you expect, is just a coil.
L7030 has no contact with any ground point; don't touch it!

You probably had bad solders on U7000 and Q7035 got burnt.
Maybe new U7000 itself was damaged.
 
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sangolossyfon

Member
Yes I ended up realizing this by testing other boards. I'm pretty new to board repair and this is just me learning fast. However when I install L7030 there is a short to ground on the entire PPBUS_G3H. So something that is not supposed to be shorted is shorted. Probably beyond L7030.

CHGR_PHASE is shorted
PPDCIN_G3H_CHGR is not
CHGR_LGATE is shorted so problem could be Q7035 or beyond that
yes probably Q7035 will replace it and get a new U7000 as well
 
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S

sangolossyfon

Member
So replaced both these chips. Now green light comes on and board can boot when plugged in or when just on battery. However... battery still does not charge. When both battery and charger plugged in, no light at all- and power usage from wall briefly spikes to ~10w then back to 0w, and green light flickers, as if battery is trying to charge for a second then quitting. Would this point to a bad solder or a bad chip somewhere else?
 
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sangolossyfon

Member
G3H voltage is 16v when charger is connected

11.6v with just battery

I will add that these voltages are the board not powered on... because it is a 2010 that doesn't auto power on

when charger connected it goes between 16v and 11.6v. on one of my chargers it only does this once before the charger shorts and shuts down.

also when I tried just the lab psu at 18.5v, the PPBUS_G3H voltage was 18v... so somehow the full charger voltage is going to G3h...
 
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