Lenovo G50-70 ACLU1/ACLU2 NM-A271 no power on - again

Hello, new user here

I'm trying to repair the same logic board posted here lenovo-g50-70-aclu1-aclu2-nm-a271-no-power-on-t42953.html
with probably the same issues, but I not have the same level of expertise, so I need some help. My story:

I'm an hobbyist without electronic skills, just willing to repair some
laptop of friends.

I have a Lenovo G50-70 ACLU1/ACLu2 NM-A271 Rev.1.0 without power at all, no
led if adapter ac connected. My friend gave me after he broken the pin of
the ADAPTER_ID of the cable. I thought I need to change only the part (DC
POWERJACK PJ718 DC30100LD00) but after reassembled all the laptop boot fine
and entered the OS, but the battery was not revealed . I thought was a
software problem: no. The laptop shuts off after 20-30 minutes, even with
the ac adapter attached. After few attempts to reboot with power button,
the laptop doesn't turn on.
I removed the battery and even with the ac adapter only attached the laptop
doesn't turn on (battery discharged? no battery charge from AC?)

I tried to reset bios desoldering and resoldering the battery: nothing
changed.

So i'm here to track down what component failed. This is my first time
trying to read a schematics but with some help form other posts, I managed
to track down these values:

-- All values are readed with no battery, ac adapter in (not original)

JDCIN1 20,3v

PF101 20.3v

PQ301
1 20.3v
2 20.3v
3 20.3v
4 0.5v
5 20.3v
6 20.3v
7 20.3v
8 20.3v

PQ302
1 20.3v
2 20.3v
3 20.3v
4 0.5v
5 20.3v
6 20.3v
7 20.3v
8 20.3v

PU301
5 0v
6 2.6v
16 6.1v
20 20.3v

PQ307
1 0v
2 3.11v
3 0
4 0
5 3.11v
6 0

PQ301/302 Pin4 voltage are ok?

I hope in some help, thanks!

PQ301/302 Pin4 voltage are ok?

Hello!
Yes, all of the measured voltages are ok.

Measure the voltage to ground on pin 72 of KBC chip (UE1).

Hello,
If i measured correctly, the voltage on pin 72 is 0,01V.

In this model, the middle pin ADAPTER_ID is very important.
Correct tension on ADAPTER_ID pin is 0.9V with 65W or 1.4V with 90W charger.
Try on another power supply.
Check the power cable middle pin at the power socket.
Measure resistance to ground on pin 72 of KBC.
Check resistor PR322.

ADAPTER_ID from JDCIN1 is 0,01V.
ADAPTER_ID from pin 72 of KBC is 0,01V
The power cable middle pin is 0,01V
I can't find the PR322... I need to remove the heatsink?

Anyway, rechecking the PU301 (somewhere from pin 16 to 20) i think i blow something... smoke from the component (resistor?) highlighted. (maybe PD303?)



Here all the new values for PU301

ACN 1 20.3
ACP 2 2.24
CMPOUT 3 0.02
CMPIN 4 0.02
ACOK 5 11.89
ACDET 6 2.54
IOUT 7 0.01
SDA 8 0.01
SCL 9 0.01
ILIM 10 0.01
BM# 11 0.01
SRN 12 0.12
SRP 13 0.12
GND 14 0.01
LODRV 15 0.01
REGN 16 0.52 to 0.72
BTST 17 0.33 to 0.58
HIDRV 18 0.12
PHASE 19 0.55
VCC 20 2.39 to 2.54

At this moment You have to replace PR308 (10Ω_1206) and PU301 (BQ24737).

Hello, I'm back! Sorry but I am a little bit sick these months...
Anyway, I replaced the PU301 - bq24737 with a bq24735 (as posted on a TI forum support) and the resistor blowned and here's my new values :

1 ACN 20.3
2 ACP 20.3
3 CMSRC 0.1
4 ACDRV 0.1
5 ACOK 0.1
6 ACDET 2.6
7 IOUT 2.3
8 SDA 3.4
9 SCL 3.4
10 ILIM 2.3
11 BATDRV 21.9 to 25.3
12 SRN 20.3
13 SRP 20.3
14 GND 0.1
15 LODRV 0.1
16 REGN 6.1
17 BTST 19.9
18 HIDRV 20.3
19 PHASE 20.3
20 VCC 20.2

Is values right?
Thanks!

Funkwarrior napisał(a):I replaced the PU301 - bq24737 with a bq24735

You made a mistake,
must be BQ24737 or BQ24727.

Hi,
thanks for the help mates.
I tried to refit the first bq24737 i tried to install, as long as I wait for the new one.

The values are correct now? (without battery attached)

1 ACN 20.3
2 ACP 20.3
3 CMSRC 1.3
4 ACDRV 0.3
5 ACOK 0.1
6 ACDET 2.6
7 IOUT 2.3
8 SDA 1.9
9 SCL 1.4
10 ILIM 1.5
11 BATDRV 0.2
12 SRN 19.9
13 SRP 0.1
14 GND 0.1
15 LODRV 0.1
16 REGN 1.7
17 BTST 1.9
18 HIDRV 2
19 PHASE 20.3
20 VCC 20.2

Thanks for the help and patience

8 SDA 1,9 Correct value=3.3v
9 SCL 1.4 Correct value=3.3v
12 SRN 19.9 voltage too high
13 SRP 0,1 this voltage must be the same as that of pin 12 unless PL302 is interrupted
16 REGN 1.7 Correct value=6v
17 BTST 1.9 voltage too low
19 FASE 20.3 voltage too high
20 VCC 20.2

Pu301 does not work as it should.
Are the welds efficient?

Thank you all for your help, but I think I fried the board... I need more experience and better tools for this kind of soldering.
Thanks again, I really appreciate your support.

Hello, I resume this thread, hopefully to resolve this problem.
I resoldered with better tools the PU301 and now I have this values using an original Thinkpad 45w power supply :
PU301
1 ACN 20,70
2 ACP 20,7
3 CMPOUT 0
4 CMPIN 0
5 ACOK 0
6 ACDET 2,7
7 IOUT 0
8 SDA 0
9 SCL 0
10 ILIM 0
11 BM# 0
12 SRN 1,9
13 SRP 1,9
14 GND 0
15 LODRV 0
16 REGN 6,1
17 BTST 5,9
18 HIDRV 1,9
19 PHASE 1,9
20 VCC 20,7

PQ301
1 S 20,7
2 S 20,7
3 S 20,7
4 G 5,1
5 D 20,7
6 D 20,7
7 D 20,7
8 D 20,7

PQ302
1 S 20,7
2 S 20,7
3 S 20,7
4 G 5,1
5 D 20,7
6 D 20,7
7 D 20,7
8 D 20,7

ADAPTER_ID pin is 0V, even on the power socket

I understand now maybe the values on PU301 are OK, except for SDA and SCL...
Maybe I have IT8586E burnt?

Measure the resistance to ground on pins 8, 9 of PU301.

8 SDA 2,2K
9 SCL 75,6K

Connect the battery and measure the voltage on pins 8, 9 of PU301.
Measure the voltages of PL302.

I got 13,26v on PL302
but 0v on pin 8,9 PU301

Measure the voltages on pins 115, 116 of KBC.
If 3v are present check the continuity between pin 115 (KBC) and pin 9 (PU301) pin 3 (JBATT1), pin 116 (KBC) pin 8 (PU301) pin 4 (JBATT1).
Measure the voltages on all pins of the battery connector with and without battery, connected power supply.

KBC Pins 115, 116 I have 0v....

Possible faults:
PU301
battery
KBC.
Replace the bios and remember to save the old one.
Try another battery.

Thanks, I will try first with a new BQ24737, probably I stressed it a lot. I will try again in a few days.
The bios is on the KBV, am i wrong?
And many thanks, Machine, You are very kind.