Lenovo Yoga unidentified component

[jasko_jacker]

Hi,
after a short circuit , the npn mosfet has burned, after a replace now the voltage reaches the motherboard but I have identified another component that has sign of burns.
I have the schematic but seem that the U40 is not the same.
Someone can identify this component.
thanks

[piernov]

Re: Lenovo Yoga unidentified component

U40 looks like the same as in the schematics to me.

[jiroy]

Re: Lenovo Yoga unidentified component

Are you sure ? , it's on Page 30/37 ..

TPS2553DRV_SON6_2X2

[jiroy]

Re: Lenovo Yoga unidentified component

I think your confusion comes from this mosfet having 7 pins .. Notice that the seventh pin is a ground pad ..

[jasko_jacker]

Re: Lenovo Yoga unidentified component

Ok (the gnd pad is under the component), i do not understand the function of this component.

[jiroy]

Re: Lenovo Yoga unidentified component

It's a part of the USB system , so if shorted , yes , it would prevent booting .

[piernov]

Re: Lenovo Yoga unidentified component

Basically it's a switch that enables/disables USB power depending on the signal present on the EN pin. Additionnally, it provides protection against over-current situation on the USB port.
Remove U40 and inject 5V on its output and check if the current is higher than it should be.
If it's fine (less than 1.5A) then you can put a jumper from input to output for testing purpose only. You'll have to replace U40 in all cases.

[jiroy]

Re: Lenovo Yoga unidentified component

Basically it's a switch that enables/disables USB power depending on the signal present on the EN pin. Additionnally, it provides protection against over-current situation on the USB port.
Remove U40 and inject 5V on its output and check if the current is higher than it should be.
If it's fine (less than 1.5A) then you can put a jumper from input to output for testing purpose only. You'll have to replace U40 in all cases.

I really wonder what "something USB" could have drawn more than 1.7 Amps , lol ..

[jasko_jacker]

Re: Lenovo Yoga unidentified component

I never fixed a motherboard of this type and If I understand well how it works:
for the moment I can not consider u40 because it does not receive + 5VDX_WALKPORT (right ?), coming from ISL95905
this is an IC Integrated Power Management (all in one, provides all the necessary voltages to major components, cpu, ram etc) and I think I should check if it works.
the datasheet is not available

[jiroy]

Re: Lenovo Yoga unidentified component

I never fixed a motherboard of this type and If I understand well how it works:
for the moment I can not consider u40 because it does not receive + 5VDX_WALKPORT (right ?), coming from ISL95905
this is an IC Integrated Power Management (all in one, provides all the necessary voltages to major components, cpu, ram etc) and I think I should check if it works.
the datasheet is not available

It would be difficult but not impossible , to determine the IC status . Try first to identify the health of the IC other's voltages . If things are constant and true , then the IC is fine and working .
In such case , you could follow the tps255XX surrounding components ..

[jasko_jacker]

Re: Lenovo Yoga unidentified component

No voltages out from PU3, it is powered by 8.4V .
Charge chip is ok, ITE is not powered but I have difficult to detect the +3v source without boardview.

[mcplslg123]

Re: Lenovo Yoga unidentified component

Why dont you remove U40 from mobo and see what happens?? Its not going to harm as its only usb power,usb port will not work. Sometimes a burnt IC may prevent other voltage rails. Just think about it.

[jiroy]

Re: Lenovo Yoga unidentified component

It's logical to assume jasko_jacker; has removed U40 by now. No reason to leave a burnt component anyway .
If ISL95905HIZ-T is acting strange , better replace it , it's available from manufacturer Intersil Corporation .

[jeroengroen]

Re: Lenovo Yoga unidentified component

I have a board with no burned components, but u40 was shorted. I've replaced that, but same as poster: no power reached. I've measured the +5VUSB on the ISL95905 and that seems to be shorted. I'm waiting on a new one now. Did you ever solve it, or do you need more info on where I measured?

[Armandio92]

Re: Lenovo Yoga unidentified component

Hi,
after a short circuit , the npn mosfet has burned, after a replace now the voltage reaches the motherboard but I have identified another component that has sign of burns.
I have the schematic but seem that the U40 is not the same.
Someone can identify this component.
thanks

Hi, we're you able to fix it? Replaced both components and still the same. I'm lost even with the schematics. CPU and BQ chip run at 40c under Thermal cam.

[chenwei]

Re: Lenovo Yoga unidentified component

This is the USB power supply chip. Can be removed directly. Then the sub 1, 6 feet