Lenovo Ideapad 3 15ADA05 / NM-C821 / It does not turn on

Sorry my mistake KBC UE1.

Zemog ha scritto:OKAY. At this moment and after changing, KBC, the damaged and erroneous chip, the board has the following voltages, let's see if someone can help me again.
+3VL ... 3,18V
+5VLP ... 4,77V
+5VALW ... 5V
+3VALW, +1,8VAWL, ... 0V

EC_ON:3V# ... 3V

In KBC:
Pin 79 (APU3VALW_EN) ... 2,70V
Pin 86 (PBTN_OUT#) ... 0V
Pin 93 EC_RSMRST#R ... 0V
Pin 110 (ON/OFF_R) ... 3.1V and when you press the power button the value drops to 0V

I have changed KBC again and the values that have changed with respect to this previous measurement are:

+3VALW ... 0,93V
EC_ON3V# ... 0V
KBC pin 79 (APU3VALW_EN) ... 0V
The rest of the measurements are the same and EC_RSMRST# continues at 0V

Try reprogramming it.

I have reprogrammed BIOS and dodo is still the same.
Bios is powered with +1.8VALW and while this is at 0V the BIOS will not work, right? All UC3 pins are at 0V

Measure the voltages on pins 4, 5, 16, 18. 19, 27 of PU1901.

Machine ha scritto:Mida los voltajes en los pines 4, 5, 16, 18, 19, 27 de PU1901.

Pin 4 ... 0,93V
Pin 5 ... 0V
Pin 16 ... 2,94V
Pin 18 ... 0V
Pin 19 ... 5,08V
Pin 27 ... 3,65V

Measure voltage and resistance to ground of PL1902.
Measure voltage and resistance to ground on all coils.

Machine ha scritto:Mida el voltaje y la resistencia a tierra del PL1902.

8K 0V

Machine ha scritto:Mida el voltaje y la resistencia a tierra en todas las bobinas.

PL1901 ... 40 Ohm 0v
PL1903 ... 60K 0V
PL5901 ... 5 Ohm 0V
PL5902 ... 5 Ohm 0V
PL5903 ... 3,5 Ohm 0V
PL 401 ... 13K 0,94V
PL 402 ... 250k 5,08V

Measure the voltages on pins 1, 2, 7, 8, 9 of PU401.

Pin 1 ... 3V
Pin 2 ... 20V
Pin 7 ... 0V
Pin 8 ... 19,84V
Pin 9 ... 0V

In PU401 EC_ON_3V (pin 9) must be present for the +3VALW_P output to be activated, is that correct?
EC_ON_3V is currently at 0V and instead at +3VALW_P I have 0.90V, why?

Exact. A residual voltage on +3VALW_P may be due to tolerances or noise.
Measure the voltages on pin 13 of PU401.

Pin 13 (+3VLP) ... 3,18V

All measures lead to failure of the KBC.

I can try to re-solder the original or previous KBC to see if the voltages are restored to the previous ones, and at the same time I will order new KBCs from other places, in case this batch has been defective.
The 2 KBC that I have placed correspond to the same order

Do the 2 KBCs tested have the same acronym?
Try re-soldering the old one and check the welds carefully.

Zemog ha scritto:OKAY. At this moment and after changing, KBC, the damaged and erroneous chip, the board has the following voltages, let's see if someone can help me again.
+3VL ... 3,18V
+5VLP ... 4,77V
+5VALW ... 5V
+3VALW, +1,8VAWL, ... 0V

EC_ON:3V# ... 3V

In KBC:
Pin 79 (APU3VALW_EN) ... 2,70V
Pin 86 (PBTN_OUT#) ... 0V
Pin 93 EC_RSMRST#R ... 0V
Pin 110 (ON/OFF_R) ... 3.1V and when you press the power button the value drops to 0V

The chip nomenclature is the same

After changing to the previous chip, the values are the same as before.

I'm going to solder another new KBC from another seller that I received and see if it's a batch error.

I have re-soldered a new KBC from another seller and they have changed some voltage but they are still bad
Now the measurements are these:
3VL ... 3.18V
+5VLP ... 4.85V
+5VALW ... 5,08V
+3VALW... 1,35V
+1.8VAWL, ... 0,1V

EC_ON:3V# ... 3,15V

In KBC:
Pin 79 (APU3VALW_EN) ... 3,13V
Pin 86 (PBTN_OUT#) ... 2,34v
Pin 93 EC_RSMRST#R ... 0V
Pin 110 (ON/OFF_R) ... 3V and when you press the power button the value drops to 0V

In this case, the processor heats up

Measure the resistance to ground of PL1902.
Open PJ1904 and measure the voltage on PL1902.
Measure the voltages on pins 16, 27 of PU1901.

Measure the resistance to ground of PL1902.

8,55K

Machine ha scritto:Open PJ1904 and measure the voltage on PL1902.

0V

Machine ha scritto:Measure the voltages on pins 16, 27 of PU1901

Pin 16... When the power is connected it gives a peak of 2V and immediately drops to 0V
Pin 27... 3,65V