HP 15 LA-C701P not turning on

[lapfix]

Hello friends
I got this motherboard that didn't turn on.
No damage , no liquid..
When i plug in the charger -PSU-the power led is on with 0.004 amp taken.
3/5valwp and 1.35vVP comes after power switching.
When i press the power button nothing happen with 0.006 amp taken ,3/5valwp are present for a couple of seconds , but no +1.35VP for Ram .

With diode mode i take all my measurements in each coil and all ok , no short to ground.

Try to clean me region for bios still the same.

this is the voltages taken from UK1 = KB9022Q

104 = MAINPWON = 0/3v
110 = EC_ACIN = 3.3
112 = EC_ON = 3.3v
100 = PCH_RSMRST# = 0v
114 = ON/OFF# = 3v/0/3
13 = PLT_RST =0v
95 = SYSON =0v

Did this lap need a IO dump!

what to check else..thank you

[mcplslg123]

RSMRST# has to be 3V. Check LIDSW# signal present or not?? RTC reset checked??

[lapfix]

Thank you mcplslg

115 = LID_SW# = 3.3v
PCH_RTCRST# and PCH_SRTCRST# = 2.96v

For PU3 the 2 enable signal not present = EN_1.35VP and EN_0.675VSP.
The SUSP# and SYSON

[piernov]

Did you follow power sequence?

[mcplslg123]

Its useless to measue SUSP#,SYSON or PLTRST when you dont have RSMRST#. Unless PCH_RSMRST# is de-asserted, PCH is not going to release SLP_S5 and so on. So those signals like susp# or pltrst are not going to rise. Dont waste your time measuring them. Need to check why RSMRST# is not 3V.

[mcplslg123]

+3V_PCH Present??PM_SLP_SUS# present??PCH_PWR_EN??

[lapfix]

Techtiger : yes...until i didn't get my 1.35vp

mcplslig : +3V_PCH not present .

Q30 :

Source = 3.364v
Gate = 3.334v ..i think for Pchannel must be 0v when Q31 is On..but it isn't
Drain = 0V

Q31 :

Drain =3.300v
Gate = 0v..that's my pb !
Source = ground

[piernov]

You didn't list the most important one… PM_SLP_SUS#.

[lapfix]

Sorry piernov , ys forget to test this ; PM_SLP_SUS#= 0V

PBTN_OUT# pin 122 = 0v than 3v

[piernov]

If PM_SLP_SUS# is 0V you are far from getting to an S3 state to get RAM power rail. As you can see from power sequence, RAM voltage turns on at step 11 while you're not even getting step 5…

Check votlage on RTCRST#, SRTCRST#, INTVRMEN, DSWVRMEN, DPWROK, PM_BATLOW#, ACPRESENT going to the PCH.

Originally Posted by lapfix

PBTN_OUT# pin 122 = 0v than 3v

Can you clarify what this means?

[lapfix]

Agree with your diagnostic..i will take the voltages of the others

Can you clarify what this means?[/QUOTE]

0V before switch on,...3v after switch on

[lapfix]

Piernov , merci l'ami.
Try to find PM_BATLOW# , It was RPH1 Close to Cpu so i take out the heatsink and surprise : YC1 was broken ( under the heatsink)...change it with the same one and all voltages rise up , the motherboard alive but no screen , just i reflash bios with the old dump and all is OK.

A big thank to mcplslg123 and Piernov.