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820-3476 No PPBUS No PP3V42

Bouba148

Bouba148

New member
Doesn't Turn ON no Green Light No History

Q7010 and R7020 Burning Hot
Replaced U7090: OK not burning anymore

PPBUS: 0V

R17/18:OK
R27/28: OK

Checked the voltages at U7100:
1: CHGR_AGATE 0V
2: CHGR_DCIN 16.30V
3: CHGR_ACIN 3.950V
4: CHGR_VFRQ 0.170 VS
5: CHGR_ICOMP 0V
6: CHGR_CELL 0.170V
7: CHGR_VCOMP 0V
8: CHGR_VNEG 0V
9: CHGR_AMON 0.031V 0.031V
10: SMBUS_SMC_5_G3_SDA 0V
11: SMBUS_SMC_5_G3_SCL 0V
12: PP3V42_G3H 0.177V

So I checked my soldering job at U7090:
I've re heated with the hot air, it moved a little bit then the PP3V42 voltage rised to 2.5V
but on Pin 6 the voltage dropped from 16.5V to 3.7V -3.21V

Checked again R7020: Burning hot again.

I think my U7090 is bad again, if so , why?

Stupid Question: Which rail should be present first PPBUS or PP3V42?
I would say both at the same time, which would mean that I have 2 issues so far on that board?
Maybe U7100 is pulling down PP3V42?
 
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2informaticos

2informaticos

Administrator
Staff member
First of all, check diode mode to ground at L7095 and L7130.
If you found R7020 burnt, check if D7005 is not shorted (both sections).
Check al caps C7090-92.
Be sure R7095/96 are both OK.
 
Bouba148

Bouba148

New member
Hi 2Informaticos,
I've already did all those checking but because of you, I've redone them and thank you because I've read 0.140V at F7140 (removed) but in the rush I've swapped the pins so I went in the wrong direction.
this value is in the direction of L7130 and U7100, by the way this one (U7100) is removed, so I would suspect Q7130 because I still have 0.146V at Pin 1 of L7130 with this one removed.
What do you think?
 
Bouba148

Bouba148

New member
Replaced Q7130 but still the same reading value of 0.140V, so I checked some other motherboard of the same generation, and it appear that at L7130 they all read the same value.
So now I'm confused because on pin 2 of F7140 i'm reading 0.465V.
And No short on C7090-92, no short at D7005.
R7095 reads 190KOhms and R7096 155kOhms both are low compared to the schematics but wompared to some other boards I have more or less the same reading.
 
Bouba148

Bouba148

New member
Replaced U7090 3 times now, still PPVIN_G3H_P3V42G3H dropping from 16.5V to 3.2V and R7020 burning hot.
Replaced C7095, R7095, R7096.
When removing u7090 PPVIN_G3H_P3V42G3H : 16.5V
I'm confused any clue?
U7100 is removed also.
 
2informaticos

2informaticos

Administrator
Staff member
Did you place U7090 in correct way?
Be sure C7094 is OK and has good contacts.
If not, U7090 gets fried.

Low-side MOSFET from Q7030 is Schottky, so diode mode to ground value is correct.
 
Bouba148

Bouba148

New member
yes U7090 is soldered corretly, when you turn it upside down there is a mark on the ground pad that matches to the ground pad on the motherboard.
I've put another LT3470 from a donor board and still the same ( now 4 + the original one that I've put in the trash).
 
J

JohnB8812

New member
Your VIN pin should not be fluctuating something is wrong there. Check that pin for a short could have problems before or after the diode. Q7080 is also suspect here. Make sure traces to U7090 are good as well
 
Bouba148

Bouba148

New member
Hi JohnB8812,

Sorry but my Vin,is not fluctuating, it's just that when I've writen that it's "dropping", I would better write : I'm mesuring 3.2V instead of 16.5V when U7090 is soldered.
Something is pulling down my Vin, and that thing is not on the Ppbus_g3h side but on the Pp3v42 side when looking from the diode "Y" path.
Maybe I should start by that DIODE D7005 ?
 
J

jadao

Member
For your VIN being low, something is going wrong on 3V42 circuit, check carefully all resistors caps around U7090.

Nothing wrong, no short with pp3v42_g3h rail?

Yes you can disconnect R7005 to isolate ppbus_g3h. You can also remove D7005 and inject 16,5V on pad 3 of removed D7005 and check how PP3V42 circuit behave.
 
Bouba148

Bouba148

New member
20190318-115723-176.jpg Sure, It's a 47 Ohms R7020 reading 47.6 Ohms that I've already replaced because the original one was OK but started to turn brown because of over heating.
Also just replaced D7005 just in case, but didn't change anything.
I think I'm missing something obsvious but can't see what.
I took an U7090 from a known good board and still the same:
PP3V42: 2.5V
PPVIN_G3H_P3V42G3H: 3.31V
R7020 burning Hot
Checked all the tracks around U7090, replaced almost all the components around U7090.
Again if I remove U7090 R7090 is NOT heating and PPVIN_G3H_P3V42G3H is 16.5V
PP3V42 is NOT shorted to Gnd as in diode mode I read 0.313V
I'm out of ideas.
Also I did te following test:
Removed U7090, injected 3.42V (300mA)
Plugged In the charger
I Still I had No PPBUS_G3H but SMC looks like OK becuse I have SMC_BC_ACOK, SMC_BC_ACOK_VCC, SYS_ONEWIRE and ADAPTER_SENSE present.
The green Light is very DIMM
Maybe I should try to fix PPBUS_G3H and then come back to PP3V42
 
J

JohnB8812

New member
I think something is messed up on your PP3v42 line or PPBUS line. I once had one like this where U1900 was causing R7020 to get scorching hot as well and was pulling down PP3v42. This could be a similar situation for you, but start by removing U7090 and injecting 3.42 volts into PP3v42. See if there is any amperage draw.
 
Bouba148

Bouba148

New member
Here my reading at U7100

1: CHGR_AGATE 0V
2: CHGR_DCIN 16.45V
3: CHGR_ACIN 4.0V
4: CHGR_VFRQ 3.322V VS 0.170
5: CHGR_ICOMP 2.851V VS 0V
6: CHGR_CELL 3.412V VS 0.170V
7: CHGR_VCOMP 2.843V VS 0V
8: CHGR_VNEG 0.890V VS 0V
9: CHGR_AMON 0.034V 0.033V
10: SMBUS_SMC_5_G3_SDA 3.32V
11: SMBUS_SMC_5_G3_SCL 3.62V
12: PP3V42_G3H 0.177V 3.393V
13: CHGR_RST_L 0.155V 3.336V
14: SMC_BC_ACOK 3.333V
15: CHGR_BMON 0.047V
16: CHGR_BGATE 5.354V
17: CHGR_CSO_N 5.366V
18: CHGR_CSO_P 5.370V
19: PP5V1_CHGR_VDD 5.425V
20: PP5V1_CHGR_VDDP 5.433V
21: CHGR_LGATE 0.00V Pulsing at the scope see picture
22: GND
23: CHGR_PHASE 5.312V
24: CHGR_UGATE 5.077V Pulsing at the scope see picture
25: CHGR_BOOT 5.336V
26: CHGR_SGATE 16.04V
27: CHGR_CSI_N 16.28V
28: CHGR_CSI_P 16.28V
 

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2informaticos

2informaticos

Administrator
Staff member
"12: PP3V42_G3H 0.177V 3.393V
-------------------------------
PP3V42: 2.5V"
Mmmmh, can you confirm what happens there???

Please provide accurate information, or the help is useless...
 
Bouba148

Bouba148

New member
Sorry It's a misunderstanding

12: PP3V42_G3H 3.393V
13: CHGR_RST_L 3.336V These values are with U7090 Removed and 3.42V injected at L7095 pin2

12: PP3V42_G3H 0.177V
13: CHGR_RST_L 0.155V These values were before I replace U7100

PP3V42: 2.5V is with U7090 soldered in place.
 
Bouba148

Bouba148

New member
I think my issue is coming from the SMC:

I've re-heated the SMC with the charger plugged in and with my fluke probe on PP3V42.
I had PP3V42 at 3.410V during the heating process but as soon as I removed the heat gun it turned back to 2.7V.

So I will try to reball it or replace it if I found the exact same donor board.
 
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