No power, charging or boot

[aaandro]

Heya

For some reason laptop refuses show any signs of life, no indicator leds, no boot or even charging indicator led.

To sum up what I've tried and figured out so far:

-Only ~0.6v on power jack on motherboard (think it's the standby volts), when power cable connected to motherboard and battery connected
-Correct voltage on power brick, measured with multimeter 19.27v, while not connected to motherboard.
-No voltage on battery ends when connencted to motherboard.
-When shorting 2 pins on battery with 100 ohm resistor, I get the correct voltage on battery. 11.88v. Not connected to motherboard
-No obvious burnt components.
-No blown fuses, just punch of polyswitches
-Cmos battery ok

-I do get about ~16mv on one of the battery pins,
-Same 16mv on power button and pulled down to ground when pressed.


I've got it up to very basics, just a motherboard with cpu, heatsink, fan, ram and battery(and tried with power cable as well) connected on my desk. Tried with power button pcb as well.

Laptop is the ms-16f2, barebones of msi gt683. http://www.msiwhitebook.com/product_spec.asp?model=MS-16f2-ID1
motherboard: Mobile Intel® HM67 Express Chipset (Sandy Bridge)

I'm running out of ideas what to test or where the fault could be, It seems to be like a power issue, but I haven't had that much experience with laptops. There could whatever transistors switching power on and off and what not.. But still I would expect to see battery voltage when connected to motherboard.

I'll post as I try other things, but slowly losing hope.
And yes I did search through punch of other topics related.

Oh few strange things did happen before this.
One day I switched laptop on and the it started switching on and off by itself going in vicious cycle, until I wiggled the power button for a bit and it stopped. Worked alright for rest of the day.
Next day I turned it on, black screen, fans going full speed. I tried to restart and here we are.
Only thing I could think of the room was a pretty humid when it happend.

So yeap, If you guys have any ideas it's greatly appreciated.

oeh wall of text..

 

[smorizio]

if the ac power brick pin is missing the o-ring or the pin inside the mb is lose or the join is broken..it could have shorted out the power board or trip a fuse on the power board. (check the mb build and replacement guild see if there a fuse on the mb that can be replaced. if not check to see if your laptop has a daughter board for the on switch. if it does it may be that the switch or a part on that board went bad.

 

[aaandro]

Doesn't seem to be broken or loose, multimeter doesn't show me any resistance across + and - power jack whether the power brick plug is connected to motherboard or not.
Also doesn't make a difference if battery is connected or not, still getting ~0.6v across motherboard power brick jack when brick is plugged to mains. As I understood the the power brick goes to standby if no load is connected. Also some of them jacks I think have some internal switches to detect if something is inserted to jack or not..?

There is a small separate pcb for power button and with few other buttons, there could be possibly something wrong on it, I'll try to fnd the right pins to short and not have the pcb not connected then.

And I do have a 20v powersupply somewhere, I'm not sure how senstive the regulators are on motherboard, if it's safe to have 20v instead of 19v. The current supply is a lot less on the 20v one. Not sure if there is any point of trying it though. Could be a chance that battery is just empty enough not to power the board and current power brick collapses under load.

About the fuses, I do see some Ro20 series fuses, thought they would polyswitches that reset themselves, but maybe I'm wrong, have to look them up. But then I would expect to see a voltage difference across the fuse then..

 

[philapeter]

AC port coming lose from motherboard? Often happens with laptops. If contact looks good, then try resoldering it. If pins and/or edges are looking abused, find a replacement online and soldering it on. Or pay fifty bucks and *** it out to a company that specializes in it. And i just noticed my comment is useless here....

 

[aaandro]

mhh.. still can't figure it out.

But would it make sense for battery to have voltage across it's terminal with me shorting 2 pins out with the 100ohm resistor, but as soon as I put it on the mb, it's just 0v(the correct pins are still shorted on mb to get the battery active).. Must be shorting something on the mb then or could a be burnt regulatar or something else...?

There is a bit interesting look capacitor though, just between battery + and -, I'll try take it out tomorrow, see if that could be it..

 

[bindiou]

hi
resistance between + and earth should be more than 100K ohms
if less than 30 ohms, you have a short
so any voltage will go to earth (dc should 19.4V or so, and power button 3.3V or so and go to zero if power button pushed only)
and pin will get hot (if power supply does not cut power, a good one should have a security)
this comes from some bad componant, either a mosfet or a capacitor or anything in parralel to earth
sometimes, power pin of dc jacks burns and you get a short to earth at the soldering point
only solution then is to modify conection to mb, isolate and bridge the dead zone
i would recomand to unsolder the dc jack and first mosfet after the jack, and check again for shorts to earth
you can check th jack and the mosfet separatly once unsoldered too
if needed , you can separate the circuit at coils if have short there both sides, just remove it and than check wich side the issue comes from
Hope it helped