Dell AW 13 R3 with cpu failure blink code

[loran]

Hi all!

I was working on my emails and suddenly the system crashed in an instant. No life sign at all. Not even power leds.
On the mainboard a mosfet was burnt (see picture) so I decided to replace the two mosfets with new AON7422G.
The part numbers are PQ300 and PQ301 (see schematics).

After the replacement the laptop shows 2 red and 1 blue blink code.
That's a cpu failure code according to Dell.
Does that mean the repair went well?

I read that a corrupt bios could be the cause for cpu failure code so I created a bios dump using flashrom (see .zip file).

I have no idea what to check next or how to check the replaced mosfets.
Very high temperature was needed to get the parts off the mainboard by heat soldering.
I'm not sure if surrounding parts are fine.

I test the laptop without RAM modules.

Thanks for reading
Luke

[piernov]

Re: Dell AW 13 R3 with cpu failure blink code

Buck controller should be replaced at the same time as the MOSFETs.
Check voltage on PL300.

RAM is required for the laptop to POST.

[loran]

Re: Dell AW 13 R3 with cpu failure blink code

Hi piernov, PL300 to GND is 0.0V.
You suggest to replace the TPS51212DSCR_SON10_3X3 (step-down controller) because there should be some voltage at PL300? Thanks!

[emestee]

Re: Dell AW 13 R3 with cpu failure blink code

Please dont remove or replace anything until you've carefully read and understood the beginners section. Then read the schematics.

[chestercc]

Re: Dell AW 13 R3 with cpu failure blink code

Sorry to be the bearer of bad news but most of the time if any kind of CPU mosfet burns out it sends charger or system voltage directly to the CPU and the CPU is finished dead burned out. This is the case on any laptop not just Dell ones - there is 0 protection if those mosfets go open circuit and send the charger voltage straight through.

[loran]

Re: Dell AW 13 R3 with cpu failure blink code

@chestercc: Thanks for sharing your experience!
Can I check if the CPU is dead?
I guess to check the CPU I have to fix the step-down controller first.

[emestee]

Re: Dell AW 13 R3 with cpu failure blink code

@chestercc: Thanks for sharing your experience!
Can I check if the CPU is dead?
I guess to check the CPU I have to fix the step-down controller first.

If CPU power lines show a short, and the CPU heats up and draws a lot of power when turned on, it's dead. But you can't know for sure until you try to start the machine knowing everything else is ok.