820-2838 won`t power up

[Glenn]

Hello. This is my first post on this forum


I have a macbook air 13 "it will not boot.

it shows green light in mega safe, but it won`t start up. (Not change to orange when battery is connected)

(I`am not an expert have never repaired LB before, but wish to learn)


For power up 820-2838 i need:

1)PPDCIN_S5_S5 VOLTAGE=18.5V

2)PPBUS_G3H VOLTAGE=8.4V

3)PPBUS_G3H_ISNS VOLTAGE=8.4V

4)PP3V42_G3H VOLTAGE=3.42V

5)PP3V3_S5 VOLTAGE=3.3V

Right?

I don`t have to check all components on same circuits?

What I have on the circuits are:

1) PPDCIN_S5_S5 VOLTAGE=3D16.7V OK

2) PPBUS_G3H VOLTAGE=3D8.4V OK

3) PPBUS_G3H_ISNS VOLTAGE=3D8.4V OK

4) PP3V42_G3H VOLTAGE=3D3.42V OK

5) PP3V3_S5 VOLTAGE= 0.33V NOT OK!

Do I have to measure all the S5 S3 ENET S0 lines to?

Tank you for answer me and help



Regards,

Glenn

 

[Crizz]

Check for short on this rail:
Diode Mode - red on GND & black on rail.

If there is no short look at U7201 TPS51980:
- check VIN-Pin23
- check EN-Pin21

what do you measure?

 

[Glenn]

No Title

ok will tray im am pretty n00b in this so i have to ask where should i set the multimeter ?
you mean i need to check short on the rail i mention on the first post ? ore this two you writ now?

(maybe stupid question)

 

[Glenn]

Whit out charger correct?

when using ->+ i get:

VIN-Pin23:0,436
EN-Pin21: 0.452

 

[Crizz]

Measure L7260 in diode mode (->+) with RED probe on GND and BLACK probe on L7260 without charger.
Put it then in volt mode and measure PIN 23&21 with the charger plugged in.

 

[Glenn]

Measure L7260 in diode mode give me 0.386

VIN-Pin23:8,39
EN-Pin21:1,58

With charger plugged in

 

[Glenn]

Measure L7260 in diode mode give me 0.386

VIN-Pin23:8,39
EN-Pin21:1,58

With charger plugged in

 

[Crizz]

You can say there is no short to ground on the Rail.
I missed to say EN PIN12 has to be high to make the whole chip to work.
PIN12: P5V3V3_REG_EN comes from SMC_PM_G2_EN!
Is this signal present?

Can you list up all EN pins? Voltages?

 

[Glenn]

Will list up all EN pins and voltages on these.
What voltage should PIN12 have?

 

[Glenn]

SMC_PM_G2_EN U7201 PIN-12 3,419 V
p5v_s5_en R7846 PIN-2 3,420V
P3V3S5_EN U7840 PIN-3 1,560V
P3V3S5_EN_L U7840 PIN-4 0,000V
P3V3S5_EN_R U7201 PIN-21 1,560V
P5VS3_EN R7251 PIN-2 0,482V
P5VS3_EN_R R7251 PIN-1 0,842V
P3V3S3_EN R7812 PIN-2 0,843V
P3V3S3_EN R7912 PIN-2 0,487V
DDRREG_EN U4690 PIN-3 0,978V
P5VS0_EN_L Q7945 PIN-3 2,969V
PBUSVSENS_EN_L R5316 PIN-1 8,23V
PBUSVSENS_EN_L_DVI R5316 PIN-2 8,31V
P1V5S0_EN U7710 PIN-2 0,000V
MCPCORES0_EN R7880 PIN-1 0,000v
CPUVTTS0_EN R7881 PIN-1 0,000V
MCP_MEM_VDD_EN U2305 PIN-2 0,206V

Have i forget someone?

Wlan i think no need to measure ?

 

[Glenn]

area around u7201 is getting hot when charger stay on. so it is a big chance for no short around that area ?

 

[Glenn]

No Title

Sorry for bad pictures. But could it be u7840 that is brooken?

 

[Glenn]

Measure C7801 PIN-1 in diode mode (->+) it jumps around 0.444-1,6xx (can`t get it) and overload.
maybe it`s me touching the ground beside C7801 PIN-2 then meshinge.

 

[Glenn]

..............

 

[Crizz]

P3V3S5_EN_R U7201 PIN-21 1,560V
should be 3,4V to enable PP3V3_S5 rail!!
It comes from U7840

All leads to U7840 and it looks ugly too --> replace

 

[Glenn]

Thank you. Then i will try to replace it. Just waiting for new soldering station China crape don't work ?

Thank for all help Crizz.

Will replay after change U7840.

 

[Glenn]

Is u7840 that one who registered battery too?
Because when battery is connected the charge only give me green light

 

[Crizz]

U7000 is responsible for PPBUS_GH3 and charging.
I don't think it is faulty because you have PPBUS 8,4V
For charging it has to communicate with the SMC and the battery. If it can't communicate there is something wrong with the data lines (Page42) or current sense resistors (Pins 17,18,27,28) but first things first.
Make sure all your S5 Rails come up then take care of the data lines!

 

[Glenn]

No Title

Smbus_smc_mgmt_scl only give me 0.489V and in diode mode 0,534 Could i found the problem?

 

[dukefawks]

Remove R7252 and see if P3V3S5_EN comes up to 3.3V. If yes then U7201 is dead.