LENOVO ldeaPad Flex 14 completly dead ,help.

[mo000]

hi everyone
LENOVO ldeaPad Flex 14 BIOS DA0ST6MB6E0 dead no led no nothing

no 3v 5v only 19v vin
no en signal

no kbc vcc 3.3v run

i suspicious in kbc should i replace it or flash ec .

[mcplslg123]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

First check whether you have 3V/5V LDO or not?? 3V LDO will power the EC.

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

first check whether you have 3v/5v ldo or not?? 3v ldo will power the ec.

3v ldo =0v 5v ldo = 0v
3VLDO shorted to the ground
but nothing gets hot and no consumption on power supply .
I desolder the power ic but short still exist with 0.01ohm to the ground

what does it mean that ?

[mon2]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Can you post the schematic & boardview files for your logic board?

[SMDFlea]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Can you post the schematic & boardview files for your logic board?

schematic and boardviews https://www.badcaps.net/forum/showthread.php?p=1056182

.

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

schematic and boardviews https://www.badcaps.net/forum/showthread.php?p=1056182

.

any idea for help
i think kbc defected but i want to be sure before desolder it .

[mon2]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

1) voltage on pin 12 (ENC) of PU6 ?

2) With the power OFF. If you remove PR96 & PR100, what are the resistance readings to ground on the respective +5V_ALW2 and +3.3V_ALW2 rails ?

3) If you leave the above 2 resistors OFF the logic board, do you see the local LDO output values on pins # 14 & 15 of PU6 ?

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

1) voltage on pin 12 (ENC) of PU6 ?

2) With the power OFF. If you remove PR96 & PR100, what are the resistance readings to ground on the respective +5V_ALW2 and +3.3V_ALW2 rails ?

3) If you leave the above 2 resistors OFF the logic board, do you see the local LDO output values on pins # 14 & 15 of PU6 ?

i think something missing , the laptop comes from another shop
PR70 PR66 missing and i can't found PR100 PR96 .

pin12 0v
pin 15 LDO3 shorted .
from the boardview PR96 AND PR100 suppose to be where the green spot .
help me to find them on the board .

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

any idea ?

[mon2]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

If you suspect there are missing resistors, trace pin 14 & 15 of pu6 with a multimeter to the pcb pads of the resistors.

Do this with power off.

Once they are found, check the voltage again on pin 14 and 15. With the missing resistors, the ldo rails have to be ON.

The short must be AFTER the missing resistors. Correct?

Either way, PU6 is looking to be defective if these 2 rails are not always ON.

Be sure that you replace with exactly the same with the "C" version otherwise these 2 rails will not enable.

Pin 12 is not related to the LDO rails on the "C" version of this regulator. However, the "A" & "B" versions are and then the rails will not enable.

You need the rails on pins 14&15 to be always ON to power critical parts of the logic board including the KBC, etc.

Be sure that vin is reaching PU6. That is required to power PU6 and to feed the LDO rails.

Post your updates.

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

If you suspect there are missing resistors, trace pin 14 & 15 of pu6 with a multimeter to the pcb pads of the resistors.

Do this with power off.

Once they are found, check the voltage again on pin 14 and 15. With the missing resistors, the ldo rails have to be ON.

The short must be AFTER the missing resistors. Correct?

Either way, PU6 is looking to be defective if these 2 rails are not always ON.

Be sure that you replace with exactly the same with the "C" version otherwise these 2 rails will not enable.

Pin 12 is not related to the LDO rails on the "C" version of this regulator. However, the "A" & "B" versions are and then the rails will not enable.

You need the rails on pins 14&15 to be always ON to power critical parts of the logic board including the KBC, etc.

Be sure that vin is reaching PU6. That is required to power PU6 and to feed the LDO rails.

Post your updates.

First no PR100 PR96 on this model just pads .
vin reaching PU6 on pin11
i remove KBC and the short is gone (kbc shorted on PIN127 VSTBY) no short on LDO3 rail
but still have no LDO3 AND LDO5 LDO3=0.04V , is this means PU6 is also defective .

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

i wonder in this model PU6 don't need En signal to generate LDO3 LDO5 or what
because i desolder KBC short gone but no LDO3 LDO5 .
-----------------------------
from PU6 schematic
ENC
(RT8230A/B/D)
Master Enable Control Input. The LDO5/LDO3 are enabled if it is within logic
high level and disable if it is less than the logic low level
-----------------------------
this means no LDO3 LOD5 without en signal so it's time to replace kbc and program it .

[SMDFlea]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

check D12 ,voltage

[mon2]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Hi.

1) We do not know yet if PU6 is defective.

2) power down -> check and post the resistance to ground on LDO3 rail @ PU6, pin 15. Use the 200 ohm scale on your meter.

3) Post the resistance to ground on LDO5 @ PU6, pin 14.

If the resistance reading is very low then yes there is a short condition on the respective rail and the power rail is shutting down due to high current draw.

4) You mentioned that PR96 and PR100 are pad shorts? If yes, desolder these pad shorts to open up these LDO3 & LDO5 rails.

Power up.

Now, do you see LDO3 and/or LDO5 output the proper voltage rail value ?

If NO to either of these required always-on rails, then PU6 is defective. Replace with the proper version of this part - see my earlier post. The suffix "C" in the part number is important.

Source the exact RT8230CGQW device and replace PU6 if you do not see the LDO3 and LDO5 rails after removing the pad shorts.

[SMDFlea]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

i wonder in this model PU6 don't need En signal to generate LDO3 LDO5 or what
because i desolder KBC short gone but no LDO3 LDO5 .
-----------------------------
from PU6 schematic
ENC
(RT8230A/B/D)
Master Enable Control Input. The LDO5/LDO3 are enabled if it is within logic
high level and disable if it is less than the logic low level
-----------------------------
this means no LDO3 LOD5 without en signal so it's time to replace kbc and program it .

Its the C version .

Master Enable Control Input. The channels are enabled if it is within logic high level and disable if it is less than the logic low level.

@mon2 is giving you some good advice

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Hi.

1) We do not know yet if PU6 is defective.

2) power down -> check and post the resistance to ground on LDO3 rail @ PU6, pin 15. Use the 200 ohm scale on your meter.

3) Post the resistance to ground on LDO5 @ PU6, pin 14.

If the resistance reading is very low then yes there is a short condition on the respective rail and the power rail is shutting down due to high current draw.

4) You mentioned that PR96 and PR100 are pad shorts? If yes, desolder these pad shorts to open up these LDO3 & LDO5 rails.

Power up.

Now, do you see LDO3 and/or LDO5 output the proper voltage rail value ?

If NO to either of these required always-on rails, then PU6 is defective. Replace with the proper version of this part - see my earlier post. The suffix "C" in the part number is important.

Source the exact RT8230CGQW device and replace PU6 if you do not see the LDO3 and LDO5 rails after removing the pad shorts.

thank you my brother for your help
I really had a true short on LOD3 rail ; the short gone after i desolder KBC
i will take the resistance to ground and post the results .

thank you again .

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Its the C version .

Master Enable Control Input. The channels are enabled if it is within logic high level and disable if it is less than the logic low level.

@mon2 is giving you some good advice

yes i make a mistake ; it's c version
c version has a different enable method .

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Hi.
1) We do not know yet if PU6 is defective.
2) power down -> check and post the resistance to ground on LDO3 rail @ PU6, pin 15. Use the 200 ohm scale on your meter.
3) Post the resistance to ground on LDO5 @ PU6, pin 14.

LDO3 ON 200ohm scale no reading , on buzzer diod mode 680
LDO5 on200ohm no reading , on buzzer diode mode 405

Hi.
4) You mentioned that PR96 and PR100 are pad shorts? If yes, desolder these pad shorts to open up these LDO3 & LDO5 rails.

Power up.

Now, do you see LDO3 and/or LDO5 output the proper voltage rail value ?

If NO to either of these required always-on rails, then PU6 is defective. Replace with the proper version of this part - see my earlier post. The suffix "C" in the part number is important.

Source the exact RT8230CGQW device and replace PU6 if you do not see the LDO3 and LDO5 rails after removing the pad shorts.

yes the short before i desolder KBC , but now i have no short on LDO3 rail I'm very sure that the kbc is the source of the short .
the short is gone on LD3 rail .

[mon2]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Are the LDO rails working without the short?

Need to confirm if this regulator ic is working for the always-on rails.

[mo000]

Re: LENOVO ldeaPad Flex 14 completly dead ,help.

Are the LDO rails working without the short?

Need to confirm if this regulator ic is working for the always-on rails.

no , no LDO3 LDO5 output .
I only have 19v vin and no output .