dell XPS 17 L702X p09e002 - completely dead

[justin35]

dell XPS 17 L702X p09e002

i have a dell xps 17inch case model : p09e002 which according dell website corresponds to XPS 17 L702X
i couldn't find a good schematic to match the motherboard.
for example on schematic pu8 corresponds to RT8207AGQW and on motherboard i have isl88731... on schematic pu7 corresponds to isl99731...
on schematics i have pu1 as TPS51427A, and on board is pu7 TPS51427A...
anyone have proper schematics for this board?
board model: dagm7mb1ae1 rev: e

now the problem:
laptop is completely dead, nothing happens if you plug the charger in, or press the power button.
i have 3.3v and 5v on motherboard on 2 separate coils which i assume they are 3.3v_alw and 5v_alw
Schematics indicates i should have 15v_alw also, but i can't find it anywhere.... and i have no idea who creates this 15v_alw, or if it really is 15v on that line...

Thanks!

Ps: attached schematics i have and some pictures i took from board.

[Techtiger]

Re: dell XPS 17 L702X p09e002 - completely dead

You have to use a original charger on the Schematic tracer PS_ID & Check the voltage on PD5 all pins

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

I am using dell 19.5v and 6.7amps charger...
Schematcis i have don't match the board... so pd5 on schematc is not the same as on board...

[SMDFlea]

Re: dell XPS 17 L702X p09e002 - completely dead

Use the Quanta GM7C schematic https://cdn.badcaps-static.com/pdfs/...95b29a4ca9.pdf

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

Use the Quanta GM7C schematic https://cdn.badcaps-static.com/pdfs/...95b29a4ca9.pdf

Thank you!!! I see pu7 and pu8 match this time!
I don’t have the board in front of my eyes, but i asume is the correct one!
I’ll check later tonight or tomorrow.

What about +15v_alw? Who creates it? I really don’t understand it’s mystery...

[mcplslg123]

Re: dell XPS 17 L702X p09e002 - completely dead

+15VALW is created by TPS51427

[piernov]

Re: dell XPS 17 L702X p09e002 - completely dead

+15V_ALW is created from +5V_ALW by a voltage multiplier using PD4 and PD5 diodes (and the capacitors around them). Output is on +15V_ALWP, switched on/off to +15V_ALW by PQ36. +3.3V_ALW is required as well since the switching of the gate of low-side MOSFET is what makes the voltage multiplier work.

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

here are some measurements:

pd5:
pin1 - 5.11v
pin2 - 5.41v
pin3 - 4.92v

pd4:
pin1 - 5.11v
pin2 - 6.62v
pin3 - 5.22v

pq36:
pin1 - 0v (in OR base)
pin2 - 6.61v (gnd OR emitor)
pin3 - 6.60v (out OR colector

pq36 shouldn't have 15v on pin 1?

pq26:
pin1 - 3,3v (gate) which corresponds to alw_on and i do have 3.3v there....
pin2 - 0v (source)
pin3 - 0v (drain)



see attachment for a differences around pq26/36 and pd4/5

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

I shorted q26 gate to drain (pin 1 to 3) with my tweezers and measured on q36 collector (pin3) 10.3v...
I know it's not enough but i got a modification.
I did not find a replacement for q26 (F1t) marking, but i'll try again tomorrow...

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

What if i infject 15@0.1 amp on +15v alw? Whould it be ok? Just to see if the board starts...

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

replaced pd4 & 5
replaced pq26 & 36
now i have 7.02v on +15v_alw(P)
so nothing...

injected 15v on +15v_alw
still nothing

pl4 and pl3 are the only 2 coils with voltage on this board... pl4 5v, pl3 3.3v

i really don't understand why +15v_alw is only 7v...

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

@techtiger
Ps_id is 3.3v on dc_in connector and also on ite chip ...

I lifted pin 3 of q36 (v out) to see if +15v_alw is created but i only get 9.8v

Any suggestions?
Thanks!

[Techtiger]

Re: dell XPS 17 L702X p09e002 - completely dead

@techtiger
Ps_id is 3.3v on dc_in connector and also on ite chip ...

I lifted pin 3 of q36 (v out) to see if +15v_alw is created but i only get 9.8v

Any suggestions?
Thanks!

remove PQ6 inject +15V to pin 3 and check PQ40 PQ38 pin 123 voltage if you get the RUN voltage PCH will get supply then press the PWRBTW and see if any changes
if not put a jumper PQ40 PQ38 pin 123 of the both fets in this way PCH will get the power then press the PWRBTW and see if any changes
check if the power button get its +3.3V
check the BIOS U9 gets voltage +3.3V
in SIO there are some more points to check but for the next time

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

Pq6? Or pq36?
At this point i can confirm i have 3.3v on pwrbtn, and when i press it it goes down to 0.
I have 0 volts on bios ic on all pins...

[Techtiger]

Re: dell XPS 17 L702X p09e002 - completely dead

Bios U9 pin 3 7 8 must have +3V with out this voltage set dead track it back , its QP6

[bachir2004]

Re: dell XPS 17 L702X p09e002 - completely dead

Pq6? Or pq36?
At this point i can confirm i have 3.3v on pwrbtn, and when i press it it goes down to 0.
I have 0 volts on bios ic on all pins...

it can seem to be a dumb suggestion,did you remove the rtc battery?i had almost the same problem yesterday on a latitude e7440,spent almost 1 hour trying to figure out the problem.(the rtc battery was good 3.2V)!!!!

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

Removing pq36 will generate 15v_alwp of 14.78v...
Why pq36? Because the schematic provided by me in the first post in not as acurate as the one smdflea provided:
https://cdn.badcaps-static.com/pdfs/...95b29a4ca9.pdf
With or without pq36 i do not have 3.3v_alw on pin 8 of bios chip u29...

I checked continuity from u29 pin8 to 3.3v_alw coil And there is none... which makes me believe there are more places where 3.3v alw is missing on the board...
I have to check them all, and run jumper wires fo each missing one and see if the board starts...
I also injected 3.3v on u29 pin 8 but no luck... and psu indicates 0.00aps load

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

it can seem to be a dumb suggestion,did you remove the rtc battery?i had almost the same problem yesterday on a latitude e7440,spent almost 1 hour trying to figure out the problem.(the rtc battery was good 3.2V)!!!!

This was one of the first thing to do, as for newer laptops this i a common issue...

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

Ok, so i have some news. I was measuring wrong voltages bor bios u29. I was measuring voltages on u18 (which is pch bios chip)...
I do have 3.3v_alw on 3 pins on bios chip u29...

Today I swapped q40 qith q41 and +15v_alwp went to 14.7v
Then i placed back q36 and +15v_alw went down to 13.6v
At this point i had pch supply 0.85 v and pch started to slowly heat, nithing major.
I measured cmos battery terminal and it was 1.1v

Then i decided to change both q40 and q41 from a donor board and +15v_alw went back to 7.1v
Changed again q40 and q41 but +15v_alw remained 7.1v

[justin35]

Re: dell XPS 17 L702X p09e002 - completely dead

well i went back to this idiotic board, and i did something.
i took out pq36 and now i have 14,7V on +15v_alwp
i took out pq40 and pq41 which were pulling down +15v_alw, and applied 15v on +15v_alw line
surprise! the power button light up. BUT no power on...
I have +5V run and +3.3V_sus

i don't know what else to do...