E1-571 ( LA-7912p) No post

[grosseader]

Hi fellows. I'm trying to revive my mom's E1-571 ( LA-7912p) i5 and HD4000 Full specs here

Laptop doesn't have visible or known issues like liquid damage or overheating.
One evening shut down went normal and in the morning:
Device won't post/boot.
-Disassembled and made hard resset.
-When press power on after electrical discharging,
device turn fan on, power LED light up, CD rom make check noises, all that for 3 seconds , nothing on screen no even backlit.

If i press power button again ONLY power led light up for 3-5secs and goes off again.

If remove power supply and try again, first scenario once and, keeps same.

Flashed both bios chips, no difference!
Any suggestions and help will be appreciated. I have schematics of motherboard. What to look for?

[caspian]

Re: E1-571 ( LA-7912p) No post

Do the CPU and the PCH get warm after turning the laptop on?

[grosseader]

Re: E1-571 ( LA-7912p) No post

Do the CPU and the PCH get warm after turning the laptop on?

No, they doesn't. For 3-5secs no change in temperature.
I was thinking on that and tried to start it 10+ times and was checking for any activity (warm up) but, none occured.

[mcplslg123]

Re: E1-571 ( LA-7912p) No post

Check U21/U22 for +3v VS/+5V VS. This mobo is known to have fault on VS lines.

[grosseader]

Re: E1-571 ( LA-7912p) No post

Those voltages i have, ONLY on 1st start after hard reset, afyer that, only power on led blink, no fan, no voltages.

[grosseader]

Re: E1-571 ( LA-7912p) No post

Check U21/U22 for +3v VS/+5V VS. This mobo is known to have fault on VS lines.

Ignore above post. Sorry, this morning was in a hurry and i got wrond readings.
U21 and U22 are fine, voltages are OK.

I've checked whole +3VALW net, and it is OK.

I have board view also. If anyone can reccomend other stuff to check-you are welcome! Meanwhile i will keep testing everything, but it is...ah... exhausting, without microscope or zoom lens .... but i'll keep going.

P.s: Can some moderator delete mine above post please!

[grosseader]

Re: E1-571 ( LA-7912p) No post

Nothing new, nothing wrong so far. I can't fine any problems. Anyone else with ides?

[KvnTM]

Re: E1-571 ( LA-7912p) No post

Post voltages of all power rails when on:
+CPU_CORE
+VGA_CORE
+VGFX_CORE
+0.75VS
+1.05VSDGPU
+1.05VS_VTT
+1.05VS_PCH +1.5V
+1.5VS
+1.5VSDGPU
+1.8VS
+1.8VSDGPU
+3VALW
+3VALW_EC
+3V_LAN
+3VALW_PCH
+3VS
+5VALW
+5VALW_PCH
+5VS
+VSB
+RTCVCC

Might be difficult as it turns off after a few seconds but that would give you a clue of what's going on.

[grosseader]

Re: E1-571 ( LA-7912p) No post

All voltages are OK. I just give up, not going to bother with this. Thank for reply!

[kropotkin]

Re: E1-571 ( LA-7912p) No post

If you would have +VGFX_CORE than you mast have many POST codess passed by platform. Did you try other CPU?