Hp ProBook 430 g3 not turnning on

[dimebags]

Hi everyone
I have got a friend hp ProBook 430 g3 laptop which was not turnning on at all, found a short at 19 volt line which was one of the vcore mosfet AON6370 and replaced it with equivalent mosfet, after that i got 19 volt, 5 volt and 3.3 volt in the circuit but the issue persist and it still the board does not turn on.
when connecting charger it shows white light and also blink orange 4 times and then turns off but voltage are present on the board.
I do noticed that i do not have voltage on pin 8 of bios chip and tried reprogramm it several times and still it does not work but strange thing is when i remove bios chip i get 3.3 voltage on bios pin pads now, how can it be ?
The bios chip does not seems to be shorted though.
Would you please help me troubleshoot this ?
Regards

[rex98]

Re: Hp ProBook 430 g3 not turnning on

Hi everyone
I have got a friend hp ProBook 430 g3 laptop which was not turnning on at all, found a short at 19 volt line which was one of the vcore mosfet AON6370 and replaced it with equivalent mosfet, after that i got 19 volt, 5 volt and 3.3 volt in the circuit but the issue persist and it still the board does not turn on.
when connecting charger it shows white light and also blink orange 4 times and then turns off but voltage are present on the board.
I do noticed that i do not have voltage on pin 8 of bios chip and tried reprogramm it several times and still it does not work but strange thing is when i remove bios chip i get 3.3 voltage on bios pin pads now, how can it be ?
The bios chip does not seems to be shorted though.
Would you please help me troubleshoot this ?
Regards

check I/O . and try to replace the bios chip with any chip thas has same voltage and MB. i also experienced this before in dell but i just replaced the bios chip with same mb and voltage in other brands.
also check ram.

[mcplslg123]

Re: Hp ProBook 430 g3 not turnning on

Bios pin8 will get voltage only after turning on-so nothing wrong there. Whenever 19V main rail is shorted, usually 1st dc-in mosfet also gets partially shorted. Check this aspect by checking the gate voltage on 1st dc-in mosfet.

PS: If the shorted Vcore mosfet is a high side one,then probably you're looking at a shorted cpu itself.

[dimebags]

Re: Hp ProBook 430 g3 not turnning on

Thnak you
I have replaced PQ26 mosfet, not sure if cpu is shorted cause resistance around it is 5 ohm which seems to be right.
Are you sure there should not be voltage on bios pins when charger is connected ? then why there is voltage on bios pin pads when chip is removed ?
Im going to test with another bios chip to be sure of this .
Also super io seems to be fine cause it read power button input though when i press power button charger port goes white and also blink orange 4 times then goes off .

[dimebags]

Re: Hp ProBook 430 g3 not turnning on

check I/O . and try to replace the bios chip with any chip thas has same voltage and MB. i also experienced this before in dell but i just replaced the bios chip with same mb and voltage in other brands.
also check ram.

Should i have any kind of always on voltage around memory power supply ?
i only have 19 volts on the drain of the mosfet of memory power supply circuit and nothing on the source and gate or at the coil.

[mcplslg123]

Re: Hp ProBook 430 g3 not turnning on

Thnak you
I have replaced PQ26 mosfet, not sure if cpu is shorted cause resistance around it is 5 ohm which seems to be right.
Are you sure there should not be voltage on bios pins when charger is connected ? then why there is voltage on bios pin pads when chip is removed ?
Im going to test with another bios chip to be sure of this .
Also super io seems to be fine cause it read power button input though when i press power button charger port goes white and also blink orange 4 times then goes off .

Yes, I'm sure. These mb uses a technology called Deep Sleep Well(DSW). this tech saves power consumption as 3V/5V rails are always suspended unless power switched is pressed. So 3V/5V will be generated only after power button press and thats why you should'nt expect any voltage on pin8 of bios chip. When you remove the bios chip, there will be voltage on pin8 as you're disturbing the DSW feature. Hope i'm clear enough.

[dimebags]

Re: Hp ProBook 430 g3 not turnning on

What else should i check then to find a problem ?

[mcplslg123]

Re: Hp ProBook 430 g3 not turnning on

Close up inspection under microscope
Any sign of corrossion/liquid spill
Power button voltage
RSMRST# staus.

[dimebags]

Re: Hp ProBook 430 g3 not turnning on

Well after to much digging around and nothing usefull i accidenatlly shorted 19 volt rail at charger connecter and now the laptop is totally dead.
the resistance on 19 volt rail is about 6 ohm which seems very low to me.
I tired injecting 2 volt with2 amps at current sense resistor and the only thing that gets extermly hot is cpu.
1- what would be typical resistance of 19 volt rail ?
2- how on earth i shorted cpu by accidentaly shorting 19 volt rail on charger connector ?
Regards

[dimebags]

Re: Hp ProBook 430 g3 not turnning on

Anyone?