Legion Y540 17irh motherboard issue ( need help to know how to diagnose my motherboard)

[Docus]

https://www.badcaps.net/filedata/fetch?id=3656522 .What`s with the dodgy looking brown wire, havn`t you got a good pair of test leads ?

Put the meter 2 clicks to the right onto the 200 scale to measure exact resistance .The buzzer on your meter will buzz at everything under 50 Ohms https://www.mastech-group.com/global/en/my70.html ,it doesn`t mean there`s a short.

oh ok thanks ou very much, the brown wire is the red test lead ( i have a good pair of test lead but i forgot them i my dad's car and always forgot to take it back🤣 .So if i understand, i have to measure them with the ohms and give the number dispalyed ? if its correct, there is the results :

Pin 3 = 03.0
Pin 13 = 1 (OL ?)
Pin 8 = 00.6
Pin 14 = 1 (OL ?)

[Docus]

ah i didnt see that there is a page 2 😮

[Sephir0th]

Are you sure that you have counted the pins right right?

However, if the measurements correct then we have definitely problems found. Voltage injection into LDO3 and LDO5 is the way to go from here.

[RethoricalCheese]

Suitable GND points are the exposed copper around the screw holes, and the metal shield of USB/HDMI connectors

Connect the black probe of your multimeter on a suitable GND, explained above, and the red probe on the point of interest, then post the readings here

You should take resistance measurements (meter on ohms scale Ω, start at 2k then go up the scale to 20k/200k/2M if you get OL or "1" on the left side) for example: from PL601 (red probe), to the metal shield of the USB port (GND, black probe), do the same for the other measurements with the black probe on GND, red on the point of interest

Those points i suggested (PLxxx, PCyyy) are alternate points to make it easier to measure, as the pins on those ICs are very close together, of course they're connected to the respective pins on the IC...

A bit offtopic but why are you so adamant on black probe on ground? I always do it the opposite because experience

[m1ch43lzm]

Voltage injection, set your bench PSU to 1V 2A, connect the + on the point of interest, on the 3VL the solder blob PJ603 is a suitable spot to solder a wire, on 5VL is PC601, the GND you can use an alligator clip on a suitable spot like a screw hole


--- off topic ---

A bit offtopic but why are you so adamant on black probe on ground? I always do it the opposite because experience

Easier to keep an alligator clip on GND when switching the multimeter from resistance to voltage, I don't like seeing the - on voltage measurements 😅
On diode mode I use the red probe on GND, as everyone does, you're measuring internal protection diodes of all the ICs in parallel on that line
This article explains how those internal diodes are arranged inside an IC, scroll down to figure 1 https://web.archive.org/web/20250513...-placebos.html

---- End off topic ----

[Docus]

Are you sure that you have counted the pins right right?

However, if the measurements correct then we have definitely problems found. Voltage injection into LDO3 and LDO5 is the way to go from here.

No, i have this... its seems that i dont have the right shématics, with yours i have those values :

Pin 3 = 1
Pin 13 = 2.7
Pin 8 = 1
Pin 14 = 1

[Docus]

Voltage injection, set your bench PSU to 1V 2A, connect the + on the point of interest, on the 3VL the solder blob PJ603 is a suitable spot to solder a wire, on 5VL is PC601, the GND you can use an alligator clip on a suitable spot like a screw hole


--- off topic ---

Easier to keep an alligator clip on GND when switching the multimeter from resistance to voltage, I don't like seeing the - on voltage measurements 😅
On diode mode I use the red probe on GND, as everyone does, you're measuring internal protection diodes of all the ICs in parallel on that line
This article explains how those internal diodes are arranged inside an IC, scroll down to figure 1 https://web.archive.org/web/20250513...-placebos.html

---- End off topic ----

So, i have to inject 1v 2a here and here ? ( waiting in response to do anything )

[m1ch43lzm]

So, i have to inject 1v 2a here and here ? ( waiting in response to do anything )

Just to make sure you're looking at the correct pins, pin 1 is marked with a dot (I placed a green dot there), then count counterclockwise, it's also marked on the board with a 1 and an arrow...

The picture posted by Sephir0th is correct and matches the boardview, you have to rotate it 180 degrees if you look at the chip orientation

Easier to measure at the points I marked on your picture, on the cap and the solder blob

Once you confirm if it's just pin 13, or both pins 3 and 13 you can proceed to inject voltage on the shorted line

[Docus]

Just to make sure you're looking at the correct pins, pin 1 is marked with a dot (I placed a green dot there), then count counterclockwise, it's also marked on the board with a 1 and an arrow...

The picture posted by Sephir0th is correct and matches the boardview, you have to rotate it 180 degrees if you look at the chip orientation

Easier to measure at the points I marked on your picture, on the cap and the solder blob

Once you confirm if it's just pin 13, or both pins 3 and 13 you can proceed to inject voltage on the shorted line

Oh thanks you very much, it make sense now so in this order its :

Pin 3 = 03.0
Pin 13 = 1
Pin 8 = 00.7
Pin 14 = 1

so i inject voltage on the green dot and also the yellow cap ? (3 and 13 ? ) (and between the gnd and the dot in question) and what i'm supposed to see ? what i have to do ? spay some isopropylic alchool ? see if it vape ? can something explode 😨?

[m1ch43lzm]

Now pin 13 is not shorted but the short is on pin 8

Start with 1v at PJ603, the only IC connected to it is the EC IT8226, add a drop of alcohol to it and see if it evaporates

If pin 8 is shorted, measure resistance to GND at PL602

[Docus]

Now pin 13 is not shorted but the short is on pin 8

Start with 1v at PJ603, the only IC connected to it is the EC IT8226, add a drop of alcohol to it and see if it evaporates

If pin 8 is shorted, measure resistance to GND at PL602

i test it like this or between the pin 8 and pl602 ?

[Docus]

i cannot say if the alchool evaporate with the room temp or with the chip temp but i'll say that i don't see the difference bewteen the time i put the voltage and the time i put nothing so i thinks nothing happen

[m1ch43lzm]

It's correct, as long as the probe is touching properly the GND, but now you don't have a short there (and there's no way you have a short on pin 8, since it goes to the other side of that inductor)
Also replace the battery on your multimeter, as it may give wrong readings

Maybe this picture is more clear

[Docus]

It's correct, as long as the probe is touching properly the GND, but now you don't have a short there (and there's no way you have a short on pin 8, since it goes to the other side of that inductor)
Also replace the battery on your multimeter, as it may give wrong readings

Maybe this picture is more clear

i don't have another battery bt i have another multimeter and it shows that :

pin 3 : 003.4
pin 8: 000.7
Pin 13: the value keeps rising
Pin 14: the value keeps dropping

[m1ch43lzm]

i cannot say if the alchool evaporate with the room temp or with the chip temp but i'll say that i don't see the difference bewteen the time i put the voltage and the time i put nothing so i thinks nothing happen

Have you checked if the alcohol evaporates here? Try increasing the voltage to 1.5v

pin 3 : 003.4
pin 8: 000.7
Pin 13: the value keeps rising
Pin 14: the value keeps dropping

EDIT:If its really at pin 8, or at PC613, it becomes more complicated to find the short with just alcohol, as that's the 3VALW line, many components connected to it

[Docus]

Have you checked if the alcohol evaporates here? Try increasing the voltage to 1.5v


EDIT:If its really at pin 8, or at PC613, it becomes more complicated to find the short with just alcohol, as that's the 3VALW line, many components connected to it

i checked the lenovo chip and nothing happen , a also tried with 1.5v but also nothing.
I remember that before i try to solder anything ,the rt658 was the only component that evaporate when i plug the charger and the last time i test it he doesn't do anything...

[m1ch43lzm]

I guess you could try removing PL602, or at least lifting one side of it, be careful not to melt the plastic connectors, then check if the short to GND on pin 8 of the RT6585 disappears
If that's the case, measure resistance to GND on either side of PL602, then inject voltage on the side it shows the short

[Docus]

I guess you could try removing PL602, or at least lifting one side of it, be careful not to melt the plastic connectors, then check if the short to GND on pin 8 of the RT6585 disappears
If that's the case, measure resistance to GND on either side of PL602, then inject voltage on the side it shows the short

so, i remove the pl602 and on one side i see 1.441 and on another side i see 000.4 so i think the short is in the RT6585 side

[m1ch43lzm]

so, i remove the pl602 and on one side i see 1.441 and on another side i see 000.4 so i think the short is in the RT6585 side

That side with the 0.4 is the output after the inductor, not on the RT6585 side, solder a wire on the shorted side from.your bench PSU and do the voltage injection, start with 1V 2A

Check what gets hot, hopefully not the PCH as it would mean the end, replacing a PCH requires an expensive BGA rework station

May be also the IT8226 this time, I don't know if it has to be programmed first by an external programmer (expensive), or if the motherboard can program an empty/new EC, some boards do, some don't

[Docus]

i can't find any point of heat with my hand (it is the right spot where i inject voltage ? )