Acer Chromebook CB3-431, N16P1 - Multiple Hardware Faults, also Schematic Please?

[reessi]

History:

Arrived no power, was told screen flickering for months then died.

Found LCD cable shredded, shorting 3.3v LCD line and possibly 13v Backlight line may have shorted to 3.3v as multiple things fried. It is my understanding that if you shorted the 3.3v line then the 3.3v regulator would shut down.

I found main fuse blown so I think 13v line was shorted, the 3.3v regulator had a dead short from it's 13v input to ground so now 13v line and 3.3v line on motherboard are shorted to ground.

Also high side switch for 3.3v LCD line was melted.
Wifi card had a short on it's 3.3v input, main chip was shorted.
MEC1322 Embedded Keyboard Controller had a small short that varied.

I replaced 3.3v regulator with a cheap buck convertor off ebay next to motherboard, removed old one, replaced wifi card, replaced high side switch and LCD cable.

When I measured 3.3v line it was at 70 ohms sometimes less to ground. I thought it was a bit low.

Laptop powered up and everything worked except Touchpad! WIFI connected.

So I powered off and connected 3.3v bench to 3.3v line and waited and found MEC1322 getting hot. So I figured thats why Touchpad does not work.

I replaced MEC1322 and now 3.3v line measures high like 900 ohms. But still no touchpad and now wifi sees networks but will not connect, says 'Unknown network error' after requesting password, tested on multiple networks.

I cannot find any other faults, 3.3v is going to the touchpad, I tried a touchpad from another Acer CLoudbook, that didn't work but had same ribbon cable, I do not know if it is compatible. Maybe I need to buy the same touchpad off ebay.

Any suggestions as to why the wifi no longer works or what else I can test for, for the touchpad. I cannot see anything in the MEC1322 datasheet about wifi so I find it strange that now it does not work after changing this, even though it requests password and then fails!!

ALso anyone have the Schematics?

I have schematics for the Acer CLoudbook.

Many thanks.

[reessi]

Re: Acer Chromebook CB3-431, N16P1 - Multiple Hardware Faults, also Schematic Please?

I also factory reset it, made no difference to wifi.

[reessi]

Re: Acer Chromebook CB3-431, N16P1 - Multiple Hardware Faults, also Schematic Please?

Pics.

[Cc1184]

Re: Acer Chromebook CB3-431, N16P1 - Multiple Hardware Faults, also Schematic Please?

Got a similar issue on the voltage frying things I believe. Cb3-431-c0ak
Afraid I can't help too much on touchpad, but I registered to reply on the wifi one that I'm pretty sure my black and white cables are reversed....of course this happened and then I reread and saw you are somehow detecting networks, so

Appreciate your photos, gives me some stuff to test and ... possibly find on ebay!

*And zooming in, a different wifi chip!

[reessi]

Re: Acer Chromebook CB3-431, N16P1 - Multiple Hardware Faults, also Schematic Please?

Hi there, so indeed the problem was that I did not replace with the same wifi card that shipped with the laptop. The one you see in the photo was from another Acer. I was confused since it could see networks. I presumed it was an all or nothing affair with wrong drivers. As it is a Chromebook you cannot change drivers. So Wifi is working now I bought an identical one off ebay. I have never seen a laptop where swapping the antenna made a difference since they are the same when you look at them in the screen assemblies.

Also I can confirm my touchpad was fried, got another off ebay and it is working. I was un-sure since no shorts on the old touchpad but makes sense since everything else on the 3.3v line was damaged!! I wanted to just buy the chip but only available from china and my friend needed his laptop back.

So everything is sorted on this one now. If you need any info maybe I can help but giving this back tomorrow.

There is no schematic that I could find.

Cheers.