Turbo-X Quanta QL4 VCORE missing

[Nightwalker]

Hello everyone

Turbo-X laptop, same motherboard as LG R590.
Laptop came after water felt on keyboard, turns on, fan start spinning for 1-2 seconds but nothing on screen(internal+external)
Clean all the board with Isopropyl.
All voltages seems ok, except VCORE voltage is 0-0.4
GPU and CPU get hot as usual but fan wont startup again, only at boot(55 C temp after 2-3 minutes)
I change ISL62882(CPU POWER IC), same readings(see attachment)
Also attached schematic!
Any ideas?

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Give voltage on all pins of ISL62882

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

Thanks for reply Atsio

But what do you mean?

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Measure the voltage with power button pressed on all pins of regulator

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

Sorry for late answer, i was out of town..

These readings are with power on(after button pressed)
If power button is off only VIN, +5,+3 are enabled
Forgot to tell, current goes at 0.86 and stays there!

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

You forgot the readings

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

I mean these readings already posted at first post are with power on!

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Sorry, I didn't noticed them

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

21.5v is a little bit high. Why is that?

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

I'm using this:
http://www.inter-tech.de/index.php?o...id=247&lang=en
As a universal adapter, for different laptops, with no problems so far.
I can take readings with bench power supply if needed ;-)

BTW, why PGOOD is 0.07v?

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

If you remove the processor, do you have any voltage on PL7? What is the resistance to ground on PL7 with and without processor?

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

No voltage..resistance with cpu is 0.8 Ohm, 2.0 Ohm without CPU

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Remove pl7 and check which side has the short

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

I remove also PL8, short is at cpu side reading 10 ohm without CPU and 2.5 Ohm with CPU
MOSFET side reading is 180 Kohm and counting..

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Do you have voltage on mosfets side when you remove PL7 and PL8?
Use the regulated power supply to inject voltage on PL7 from the CPU side. Set voltage 0.5v and 0.5A and check if anything is getting hot. If there isn't any responce, increase amps slowly and check. Do that without CPU.

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

No voltage at all!
BUT..
I found the short, it was at PC172 NEC/TOKIN capacitor inside CPU socket. I begun desolder these caps before go with "whats hot" procedure and with the first i removed, short disappear. Now resistance is 50 Kohm falling without CPU, 28 Ohm with CPU!
After replace, next step is to replace again ISL, do you think its already fried?

[atsio]

Re: Turbo-X Quanta QL4 VCORE missing

Replace the TOKIN and then deside for the ISL

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

Tokin replaced, now i have 0.04V at PL8, PL7 with and without CPU.
PQ44, PQ45 mosfets (AON6428L) are fried..
http://www.aosmd.com/pdfs/datasheet/AON6428L.pdf
Can i replace them with:
http://www.vishay.com/docs/73451/73451.pdf

??

[joelz]

Re: Turbo-X Quanta QL4 VCORE missing

Try to Remove PR34,PR23,PR38 end PR37 this will cut Isum- end Isum+ pin on isl626882 to calculed volted for feedback from inductor PL 7 power on the laptop end try to measure on PL7

[Nightwalker]

Re: Turbo-X Quanta QL4 VCORE missing

Hello again!

I decide to change all mosfets with the originals(PQ45, PQ44, PQ39, PQ34 with AON6428L and PQ42, PQ41, PQ38, PQ33 with AON6718L) also change again the ISL.
Same result, 0.04V at PL7, PL8 without CPU.

Also remove the four resistors as Joelz suggest, power led flashing after power button pushed, 0.01V at PL7. With resistors back, power led stable and 0.04 again.

Any suggestions?