please help friend's thinkpad T480 NM-b501 dead, VSYS_OUT 9.2v, thank you

[fredyjbi]

Please help sir, this board does not turn on because VSYS_OUT is 9.2v, I compared it with a normal board VSYS_OUT is 10.2v, I have replaced the PQ101 and PQ102 mosfet and BQ 25700 which is known to be good, but the results are still the same, thank you

VSYS_OUT 9.2v
Meter in resistance mode auto range 6M ohm ok

NORMAL BOARD VSYS_OUT 10.2V

LINK to schematic -> https://www.badcaps.net/forum/troubl...b501-schematic

PQ101
PIN 2 20V
PIN 7 0.004V
PIN 6 6V
PIN 5678 0V

PQ102
PIN 567 0V
PIN 9 0.004V
PIN 234 9.2V (VSYS_OUT)

PU101 BQ25700ARSNR
1 VBUS 20V
2 ACN 20,21V
3 ACP 20,21V
7 VDDa 6v
5 chrg_ok 0v

[mon2]

Share the voltage to ground of:

I2C_CLK_CHARGE
I2C_DATA_CHARGE

I2C_CLK_BT1
I2C_DATA_BT1

[fredyjbi]

I injected 10.2v on VSYS_OUT everything looks fine, please sir mon2 help me complete this board thank you

[mon2]

Be very careful about high voltage injection because if there is a leaking high side mosfet, the high voltage will enter the low voltage devices and can cause damage.

From this last test, the unit powers up ok with 10v2 injection?

This voltage is configured using the I2C / SMBUS lines so do review their voltage to ground.

[fredyjbi]

Share the voltage to ground of:

I2C_CLK_CHARGE
I2C_DATA_CHARGE

I2C_CLK_BT1
I2C_DATA_BT1

Thank you sir for your help. I have 2 boards with the same case
I2C_CLK_CHARGE 001.4v
I2C_DATA_CHARGE 001.4v

I2C_CLK_BT1 R10255 pin 1 0v
I2C_DATA_BT1 R10256 pin 1 0v

[mon2]

I2C_CLK_BT1 R10255 pin 1 0v
I2C_DATA_BT1 R10256 pin 1 0v

Remove all power -> meter in DIODE mode -> red meter probe (yes RED) to ground. Black meter probe on point to test.

Test:

PD7
PD8

Post each diode mode measurement.

[fredyjbi]

Remove all power -> meter in DIODE mode -> red meter probe (yes RED) to ground. Black meter probe on point to test.

Test:

PD7
PD8

Post each diode mode measurement.

dioda mode
PD7 870
PD8 870

[fredyjbi]

Remove all power -> meter in DIODE mode -> red meter probe (yes RED) to ground. Black meter probe on point to test.

Test:

PD7
PD8

Post each diode mode measurement.

Sorry, I'll correct you in advance, sir, I don't have VCC3M 0v, thank you

[mon2]

That was my next question

With no power, what is the resistance to ground of VCC3M ? Do you have a voltage @ M_ON which is the enable for this power rail ? If this power rail is shorted or is drawing too much current, then M_ON will be OFF.

[fredyjbi]

That was my next question

With no power, what is the resistance to ground of VCC3M ? Do you have a voltage @ M_ON which is the enable for this power rail ? If this power rail is shorted or is drawing too much current, then M_ON will be OFF.

ha.. saya tidak memiliki tegangan M_ON 0V pak, VCC3M PL202 dioda mode 822 baik baik saja

[fredyjbi]

That was my next question

With no power, what is the resistance to ground of VCC3M ? Do you have a voltage @ M_ON which is the enable for this power rail ? If this power rail is shorted or is drawing too much current, then M_ON will be OFF.

Thank you very much for your help sir. I have been working with this mobo for 4 days and it still won't turn on hi...
VCC3M 0V
M_ON_1 0v
Remove all power -> meter in RESISTOR mode
VCC3M 10K ohm
M_ON_1 3m ohm

[mon2]

To confirm your post # 2 - with an external power supply injection of 10v2, the board works fine?

How is the operation of this board using a charged battery?

[fredyjbi]

To confirm your post # 2 - with an external power supply injection of 10v2, the board works fine?

How is the operation of this board using a charged battery?

Sorry sir, I'm late in giving an answer, the battery is damaged so I can't try, but I installed an adapter and injected 10.2v into VSYS_OUT, the result is the same, it still won't turn on, where else should I check, is there a problem with the charging IC circuit, thank you

[mon2]

With no power to the board. Meter in resistance mode. Measure the resistance to ground of each inductor on the board. Usually they are grey in color. Checking for a shorted power rail on the logic board. Post any suspects that you find.

[fredyjbi]

With no power to the board. Meter in resistance mode. Measure the resistance to ground of each inductor on the board. Usually they are grey in color. Checking for a shorted power rail on the logic board. Post any suspects that you find.

OK, wait a minute, I'll take measurements

[fredyjbi]

With no power to the board. Meter in resistance mode. Measure the resistance to ground of each inductor on the board. Usually they are grey in color. Checking for a shorted power rail on the logic board. Post any suspects that you find.

Meter in resistance mode auto range
PL201 VCC5MP 989 ohm
PL202 VCC3M 900k ohm keeps dropping
PL701 VCC1R0_SUS 18 ohm
PL301 VCC1R2AP 350 ohm
PL702 VCC1R8_SUS 1,2M ohm keeps dropping
PL101 17K ohm
PL403 VCCGFXCORE_I 10 ohm
PL401 VCCCPUCORE 7 ohm
PL402 VCCCPUCORE 7 ohm
PL404 VCCSA 21 ohm
L6 VCC0R9_TBT_SVR 1,6 k ohm
L51 VCC3_SUS 700k ohm keeps dropping

[mon2]

These look like good values to me. Suggest for you to (carefully) review the voltages to ground of these same inductors on the known good board -> make a table of these measurements. Then compare the same measurements on this non-working board.

[fredyjbi]

These look like good values to me. Suggest for you to (carefully) review the voltages to ground of these same inductors on the known good board -> make a table of these measurements. Then compare the same measurements on this non-working board.

Oh, that means sir, it's not a problem with the charging block, because the charging IC produces the VSYS_OUT vin, and sir, I compared it with a normal board which is different only on the PL701 VCC1R0_SUS 18 ohm, on the normal PL701 board 28 ohm, thank you very much sir for your help

[mon2]

IMO, the 10 ohms difference is very small. To completely rule out the charging IC -> carefully (!!) measure the voltage to ground of each pin on both boards and post the full table of values.

It is possible that the working board is sending out a 'power good' signal to inform the rest of the board to power up and the non-working board is missing such a signal. Be sure of your soldering of the replaced parts. As far as I know, the actual output voltage is configured using the I2C / SMBUS SCL & SDA lines. The ultimate would be to monitor this bus traffic to understand what communication is ongoing from the SMBUS master and this SMBUS slave chip (charger IC). If there is a fault condition, the SMBUS analyzer logs will reveal them.

Consider to measure the voltage to ground of each pin on the charger IC with a known good power adapter on this board. Then repeat with the working board.

[fredyjbi]

IMO, the 10 ohms difference is very small. To completely rule out the charging IC -> carefully (!!) measure the voltage to ground of each pin on both boards and post the full table of values.

It is possible that the working board is sending out a 'power good' signal to inform the rest of the board to power up and the non-working board is missing such a signal. Be sure of your soldering of the replaced parts. As far as I know, the actual output voltage is configured using the I2C / SMBUS SCL & SDA lines. The ultimate would be to monitor this bus traffic to understand what communication is ongoing from the SMBUS master and this SMBUS slave chip (charger IC). If there is a fault condition, the SMBUS analyzer logs will reveal them.

Consider to measure the voltage to ground of each pin on the charger IC with a known good power adapter on this board. Then repeat with the working board.

Sir, I just measured the normal board on the U101B VREGIN20, it measured 9.6v, and on the problematic board it was only 1v, maybe this is the problem, please help me investigate this, sir, thank you