7720G suddendly die

Hi.

i don't know how or why, after a perfect restore, i shutdown the computer
normally, no prob at all.

i want to power on, but.... nothing :

No Powerlight (green ring) , no battery light, NOTHING

i remove the battery, the psu trying to hold the powerbutton more than 30
seconds,etc...

i think the psu was dead, but i have a 2nd 7720g and try it : no prob

No storm, no static electricity, no dust in fan....
I decided to open the case, and inspect the Motherboard :
There's no trace of overheating,burning component,etc...

Did someone here experienced a similar problem ???

Hope someone can help me

Regards

 

Power regulator failure, or a bad EC.

Or, did you play recently with the BIOS? (A mis-flashed BIOS produces exactly these symptoms, but it still reacts to Fn+Esc, while a dead EC or power circuit will not respond even to Fn+Esc.)

 

Hi

In first, huge thanks for your reply.

i use modded Dummy bios (marcan's blog : Abort,retry, hack? webpage) but on my other 7720G

No, i try the "Fn+esc" too, and there's no response

I'm familiar with SMD hot-air soldering, reballing,etc...

i see a Fix Ya thread about capacitor problems :

http://www.fixya.com/support/t2804733-5920_will_not_turn_adaptor_green_light

Can you indicate me which other component (voltage regulator for ex) on the motherboard could be dead ?

A BIG BIG BIG thanks.

 

A fuse could be it, or perhaps a MOSFET in the power regulation circuitry.
BTW, do you get no orange flash around the power button when you plug in the charger with Fn+Esc pressed?

 

Hi.

No, no Orange flash

 

Then it's almost certainly the 5VSB or 3VSB rail. Consult a schematic, it's easy to find one on Google. (I won't post a link, as that would be copywrong.)

 

Ok, i'm looking for that immediately

Find the schematic for Rev 1A

i have the power circuit schematic under my eyes, and i can see +5VALW and +3VALW (always on)
But the first voltage when you push the power button came apparently from the +5VALW.

Apparently, the +3V (3.3v) arrived 2 milliseconds after.

This one is needed to supply south bridge.

There's a lot of possibilies of dead component

don't hesitate to correct me if i'm wrong.

Regards

 

First try checking with a multimeter if either +5VALW or +3VALW is missing.

 

Hi

Ouch.....

+3VALW : 110 mV..........
+5VALW : 90 mV.........

What's wrong ? Can you indicate me the most logical way to search after
the faulty component ?

Regards.

 

Check if there is a short on either of the ALW lines causing the voltage to drop.

Also, is there any change in the ALW voltages if you press the power button?

(One thing is sure now: it's not a burnt-out fuse. Otherwise you would get 0mV on both ALW rails.)

 

No short-circuit.

I try to measure the ALW line, and press the power button simultaneously :
Same voltage...

I'm trying to use the battery only, to see if i have the same voltage : 0 mV !!!

The next step Master ?

 

At this point, try following through the schematic to see where the AC power "disappears" in the circuit. Replace the dead component (the one that causes power to disappear).

 

Hi Netrolller 3d !!
I have 7720 too and when I try to get to recovery mode I get orange flash around the power button and on the bulb symbol in front of the laptop when I release power button and nothing more happens. Do you have an idea what it can be?