on off problem with new71 la-5893p

[mitu_sharma]

hi friends

i need ur help
this laptop came with onoff problem
when i press power btn its on then off again and again

i tried check out all the cores present but one is missing (Pl9)
according to schematic i tried to chk all voltages related with pl9 core
so i found that this core genrate automatically the problem somewhere else
i tried many things but no luck what could cause this?? please help

[smali]

Re: on off problem with new71 la-5893p

where is schematic?

[mitu_sharma]

Re: on off problem with new71 la-5893p

here it is

[smali]

Re: on off problem with new71 la-5893p

First check the short circuit of PL9 with Ground. how many ohms with ground of PL9?

[mitu_sharma]

Re: on off problem with new71 la-5893p

6 ohm

[smali]

Re: on off problem with new71 la-5893p

ok check the voltage on PR128 both legs if you received 3 volts then remove PR130 for temporary checking and check voltage on pl9.

[mitu_sharma]

Re: on off problem with new71 la-5893p

no resistor placed on that location and no voltages present on pr128 both empty legs

[atsio]

Re: on off problem with new71 la-5893p

Probably problem with gpu, reflow or better reball.

[mitu_sharma]

Re: on off problem with new71 la-5893p

today i spent lots of hour to solve this problem but no result

i reball nvidia but still same

[highpulse]

Re: on off problem with new71 la-5893p

5891p , make sure , near the trackpad button they are usually with a black tape on it , lift it and chek the components in that area !

[highpulse]

Re: on off problem with new71 la-5893p

and add some of does with main bios issues as well, very rarely i replaced a video chip or reballing on this units

[mitu_sharma]

Re: on off problem with new71 la-5893p

as i told i checked all the component no one is faulty
i cant understand where i make a mistake

[highpulse]

Re: on off problem with new71 la-5893p

well if it does shutdown after turning on , chek S3 S5 stages problems is somewhere on hardware starting .

[LP_tekh]

Re: on off problem with new71 la-5893p

You need to replace the gpu with a new one. Reball does not solve the issue, if the bga chip is faulty.

[highpulse]

Re: on off problem with new71 la-5893p

disable GPU and if machine still turning on and off NOT GPU issue !

[sopik78]

Re: on off problem with new71 la-5893p

Well, I had similar issue on a few 5742's. As I remember that was 5894P board, but it doesnt matter.

First was BIOS issue, I had to try three different BIOS dumps and flash it 3 times until it works.

Second one fixed reballing Intel PCH.

As far as I understood here, you have no power on VGA, so try to check VGA_ON and DGPU_PWR_ON signal. I quess the problem here is problem on PCH as well.
The same I had on some Samsung N350 few weeks ago.

[highpulse]

Re: on off problem with new71 la-5893p

i agree here with sopik , i believe much more problems on PCH rather than gpu . meanwhile you got a short or else machine would start , so you must chek all coils on S0 S3 andS5 you must chek resistivity on all states to know wich is shorting !

[bilinch]

Re: on off problem with new71 la-5893p

Today another La-5893P comes again. The problem is power on then off like mitu_sharma. I check the board and find that ethernet component (U39) is getting hot. After unsoldering it, everthing is fine.

[rubbert]

Re: on off problem with new71 la-5893p

Hi everybody
I found this page because my old laptop is doing same behaviour, turns on/off (5 secs cycle). It is Acer Aspire 5741G, motherboard new71 la-5893p rev 1.0 (different than mitu_sharma, rev 0.1)
found schematics here https://cdn.badcaps-static.com/pdfs/...161e700b97.pdf

I tried all options mentioned in this thread, still no luck.
I can say that PL9 is 3 Ohm. is it good or bad?


few details more:
1+ year ago this laptop had some issues at boot, sometimes it turned off in few seconds but with a 2nd start it used to work. after few months it did not turn on.
I disassembled it and did a quick investigation, unsolder the CMOS battery and ... forgot about thies laptop, because my sister had another one meanwhile and I had my university course to finish.
today I took it again, plugged the power and found this.
differently from past it starts, but ...

any idea on additional checks?
btw what is S0 S3 ... I cannot find in schematics.
thank you very much in advance