Acer chromebook 311 c733 dead

[smic717394]

Hi,

I need a bit of help identifying few ics or maybe locate the schematic. I have a Acer chromebook 311 c733, it have the usb c clocated on the daughter board damaged, the one on the motherboard at the first glance didn't look too healthy, but inspecting it under the microscope looks good enough. The laptop is dead, no light mothing.
I disconnect everything and connecting the usb chatger to the motherboard usb c, one of the IC gets mad hot, i cant find any info about it, its marked LE=7H (on the photo is marked red), it gets to about 90 degrees. Near by there is another 5 pin double diod or ic, whatever is marked 5AF1Y (marked green), this have 3v on some pins , cant rememter what pins, if I remove this, and connect the charger , its still dead but the IC that was getting mad hot, doesnt get that hot anymore, beside it looks like it outputs 3v on some pins, but it have few pads that goes to the coil, maybe the output, that have no voltage. The 2 capacitors marked yellow that are connected to the input of the ic, vave 14v.

I need a bit of help identify this 2 ics or mayme the schematic.



Thank you.

[Sephir0th]

Re: Acer chromebook 311 c733 dead

The IC you're looking for is a RT6258B, so you're probably dealing with a short to GND at either LDO3 or LX.

[smic717394]

Re: Acer chromebook 311 c733 dead

Thank you. I,ll have a look tomorrow. I'm sure I seen the 3.3v so ldo must be good. I think ill remove the coil from the output and see if It still gets hot, maybe inject 0.8v each pad of the coil see pn what side is the short.

What should the lx voltage be?

[Sephir0th]

Re: Acer chromebook 311 c733 dead

Anything which is normally supplied from 3.3V buck converter. Load switches, some ICs and also the PCH equivalent of the SoC. With some luck, a capacitor.

[smic717394]

Re: Acer chromebook 311 c733 dead

Anything which is normally supplied from 3.3V buck converter. Load switches, some ICs and also the PCH equivalent of the SoC. With some luck, a capacitor.

Normally the LX pin is 3.3v? They have 2 pins together joind on a big trace that looks like a main power rail.

[Sephir0th]

Re: Acer chromebook 311 c733 dead

LX is the designation from Richtek for any VOUT. In your case it is the 3.3V Rail.

It is a fact. However, if you don't to agree and want to discuss this instead, then you probably don't need assistance anymore. Regards.