HP 15 LA-E811P no video

[ruletero]

Hi everyone

Please help to fix this laptop, HP 15 with LA-E811P motherboard, it turns on but without video, no schematic available, I have been using LA-D707P.

I have programmed BIOS several times with different files without success.

It consumes only 192 mA, cpu is a little hot and it restart continuosly (each 12 seconds).

It has voltages en all the big coils, 3valw, 5valw, cpu_core (1 v), bat+ (2.8 v), ddr3l (1.35v).

Other voltages I have checked:

VR_ON = 3.3v en PUG1 pin 26 (cpu core IC) RT8171C (3L =)
VR_READY pin 17 only 1.04v
PLT_RST# pin 13 KBC has 3.3v

How could I continue checking this fail?

thank your for your time and for your help.

Schematic https://www.badcaps.net/forum/showthread.php?t=84041

.

[ruletero]

Re: HP 15 LA-E811P no video

Nobody? Please help or what thing could I to check? I don't know how to continue :/

[mcplslg123]

Re: HP 15 LA-E811P no video

Consumption on Dc supply-With Ram/Without Ram??

[ruletero]

Re: HP 15 LA-E811P no video

Hi mcplslg123

It consumes 180 mA without Ram installed and 190 mA with Ram

[mcplslg123]

Re: HP 15 LA-E811P no video

This is a celeron or PDC motherboard-so the consumption at 192mA is not bad. Have you flashed bios?? Check DRamrst# present or not on pin30 of ram slot.

[ruletero]

Re: HP 15 LA-E811P no video

Hi friend

It has a Intel Celeron N3060 1.6GHz SR2KN and dramrst# is 0v and yes, I have flashed bios several times with several files. I'm reading about that signal.. :/

[ruletero]

Re: HP 15 LA-E811P no video

I have been checking PG of the IC's.

Cpu core IC is RT8171c (3L=) and its PG (VR_READY) has 1.05v only, there is another RT8171C ( I guess for GFX) and it has 3.3v in PG.

Coould it be bad?

[mcplslg123]

Re: HP 15 LA-E811P no video

Going by my experience this 3L IC always go bad on LA-E811 as well as LA-C811. Better to replace it. Check whether the Source & Gate of mosfets connected to this IC is showing short. If yes, that's a sure sign of Ic being bad. Perhaps one of the IC uses a dual channel mosfet and the other iC has 2 separate mosfets(going by LA-C811P design)

[ruletero]

Re: HP 15 LA-E811P no video

Each IC (3L) works perfectly, it has 1.03v in its coil. The only difference is the PG signal: the first one (uses 2 mosfets, vcore) has 1.05v, the other (uses 1 IC with two mosfets) has 3.3v.

I replaced the IC with the lower PG, same result, not changes. Checking the datasheet, I see that the PG value is correct, I attach the graphic.

Please help how to continue.

[ruletero]

Re: HP 15 LA-E811P no video

And excuse me, I have a question about of similar cases in the forum...

Why you ask for "does numlock or capslock led glows?".

What is the meaning of this action? o better, why the question?

thank you friends

[Stevedb]

Re: HP 15 LA-E811P no video

Hi

Ik capslock and numlock lights means that the board is posting and the bios probably good is.

Regards

Steve

[ruletero]

Re: HP 15 LA-E811P no video

Hi

Ik capslock and numlock lights means that the board is posting and the bios probably good is.

Regards

Steve

Thank you Stevedb, I'm a newbie yet xD

[mcplslg123]

Re: HP 15 LA-E811P no video

Hi friend

It has a Intel Celeron N3060 1.6GHz SR2KN and dramrst# is 0v and yes, I have flashed bios several times with several files. I'm reading about that signal.. :/

Lets check the ram ic requirement and voltage on dimm slot. Without Dramrst#, it will never post.

[ruletero]

Re: HP 15 LA-E811P no video

I see dramrst# is generated by PCH, I don't know the requirements to do it...

I did next ram checking by using the instructions en this thread:

https://www.badcaps.net/forum/showth...hlight=DRAMRST, my readings in red:

±+++++++++++++++++++++++

DDR 3L ram section voltage check list at ram slot

DDR3L operating voltage VDD (at coil )= 1.35V PINs 75,76 ram slot 1.34V COIL AND pin 76

VRef_DQ = 0.67 V at PIN 1 0.67v pin 1 (without ram)
VTT/Termination voltage= 0.67V PINs 203,204 0.66 pin 204

VRef_CA. = 0.67V PIN 126 0.67 pin 126
VDD SPD = 3.3V PIN 199 3,32 pin 199 (without ram)
SDA data = 3.3V PIN 200 3.30 pin 200
SCL clock = 3.3V PIN 202 3.30 pin 202
DRAM_RST# = 1.35V PIN 30 0v pin 30



±+++++++++++++++++++++++++++++

[mcplslg123]

Re: HP 15 LA-E811P no video

Readings are perfect. BTW, DRAMRST# comes from cpu memory controller and not PCH. I dont see any reason for Dramrst# not appearing and to me it seems like SOC memory controller section has gone faulty. I'm fighting the very exact problem on an acer E1-432 with EA40 HW mb-no dramrst# though i've checked all the ram ic requirement, ram slot pins voltages, flashed factory bios.

PS: Try changing the flash drive for bios and reflash only with HP offsite bios with matching BID to rule out bios issue.

[limpidity]

Re: HP 15 LA-E811P no video

Readings are perfect. BTW, DRAMRST# comes from cpu memory controller and not PCH. I dont see any reason for Dramrst# not appearing and to me it seems like SOC memory controller section has gone faulty. I'm fighting the very exact problem on an acer E1-432 with EA40 HW mb-no dramrst# though i've checked all the ram ic requirement, ram slot pins voltages, flashed factory bios.

PS: Try changing the flash drive for bios and reflash only with HP offsite bios with matching BID to rule out bios issue.

Is it exactly a cpu problem? Or did you solve it? I'm in the same situation

[mcplslg123]

Re: HP 15 LA-E811P no video

Is it exactly a cpu problem? Or did you solve it? I'm in the same situation

I've read your thread and in my experience DramRST# reistance to GND below 3K ohms is usually 'coz of bad cpu(not pch). This is most common problem on 4th/5th gen SOC's.

[limpidity]

Re: HP 15 LA-E811P no video

I've read your thread and in my experience DramRST# reistance to GND below 3K ohms is usually 'coz of bad cpu(not pch). This is most common problem on 4th/5th gen SOC's.

Thank you for your answer