Lenovo Legion 5 Pro 16ACH6H Water Damage

[khaahk]

Incredible mess.

Agree here
About measurements to take:

See what voltages are coming up, are 3.3V and 5V stable? Does ram/cpu core get any voltage (if you have oscilloscope would be better to see if there is at least a try to start it).
Is b+ stable or fluctuating? (if not stable indicates some failure at later stage power rail) etc.
PL1009 is still the same resistance?

[Andreasbest]

Please tell me exactly where you want to measure 3v and where 5v. PL1009 @ 18ohm

[khaahk]

You'll have to make some effort on your own, on the schematic power controllers start from page 89 with charger, then there comes 3v and 5v.
For B+ you can measure on PR5401, 5V is on PL6202 etc... - you have the schematics and boardview, use them.
Check which voltages are present, are they stable, what changes after power button is pressed. As you are using original power supply then we can not get information about power consumption to make some conclusions this way.
Also as this is liquid damage there can be bad connection anywhere on the board, some resistor with damaged contacts and that alone can be the reason for no start. So visual inspection is important.


Voltage rails are on page 6, after cmos reset the board should start right away after receiving power.

[Andreasbest]

You'll have to make some effort on your own, on the schematic power controllers start from page 89 with charger, then there comes 3v and 5v.
For B+ you can measure on PR5401, 5V is on PL6202 etc... - you have the schematics and boardview, use them.
Check which voltages are present, are they stable, what changes after power button is pressed. As you are using original power supply then we can not get information about power consumption to make some conclusions this way.
Also as this is liquid damage there can be bad connection anywhere on the board, some resistor with damaged contacts and that alone can be the reason for no start. So visual inspection is important.


Voltage rails are on page 6, after cmos reset the board should start right away after receiving power.

Οκ, PL1009 @ 18ohm is indicating short?

[khaahk]

18 ohm might be totally normal resistance for cpu core or integrated graphics controller knowing that it is a low voltage rail. If you have that resistance on B+ or 3/5V rail then this is not normal.
For now measure voltages on inductors, see which ones are present and stable. Does anything change if power button is pressed, if long pressed does power state change. If you have a power meter use it to see how much power is drawn. Post results.

You should get some understanding what is going on, just a starter from Rossmann for example.

[Andreasbest]

You'll have to make some effort on your own, on the schematic power controllers start from page 89 with charger, then there comes 3v and 5v.
For B+ you can measure on PR5401, 5V is on PL6202 etc... - you have the schematics and boardview, use them.
Check which voltages are present, are they stable, what changes after power button is pressed. As you are using original power supply then we can not get information about power consumption to make some conclusions this way.
Also as this is liquid damage there can be bad connection anywhere on the board, some resistor with damaged contacts and that alone can be the reason for no start. So visual inspection is important.


Voltage rails are on page 6, after cmos reset the board should start right away after receiving power.

PR5401 PC6202 PC6210 @ 0.8 but sometimes sparks up to 1.5v and then drops again at 0.8 or lower.
PL6202 @ 0v
No reaction when i press the power button.
4v @ PQ111 and PQ110
3.3v @ PQ112 PR113 PR115 PQ113 (PIN 3)
0v @ PR127 RX10 RX8


Not sure if i'm proceeding correctly, schematics always looked like alien language to me.

[khaahk]

You still don't have solid B+ main power rail.

Resistance to gnd on PR5401 ?
Measure resistance to gnd on all inductors (PLxxx) and post results.

[Andreasbest]

You still don't have solid B+ main power rail.

Resistance to gnd on PR5401 ?
Measure resistance to gnd on all inductors (PLxxx) and post results.

PR5401 to GND 9.5KΩ
PLU1 1.5K
PL6202 9K
PL6201 2.6K
PL7901 60K
PL3001 0.6K
PL5401 33K
PL6601 2.5K
PL4006 125Ω
PL4005 125Ω
PL2001 2002 2003 2004 2005 1Ω
PL7701 73Ω
PL1009 16Ω
PL1003 1004 1005 1006 7Ω

[khaahk]

Can't find any obvious problems here. Next i would look at the charger again, connect adapter and retake the voltage measurements on every pin. Post a clear picture of charger area (PU5401).

[Andreasbest]

Original psu is 300W and the one i use is 170w.
Perhaps this is the problem?