Dell Latitude E5540 power On than Off after 5 seconds.

[lapfix]

Hello my friend.
Dell Latitude E5540 LA-A101P power On than Off after 5 seconds.

At first i find a burned Capacitor PC437 ,after desoldered try to power on , laptop is on , fan spinning , 0.440 amp taken ; 5 seconds and he is

Off.

With diode mode try to find any short at all coils , but all is OK.

In this 5 seconds try to take the voltages :

Pl 400 = 19V
PL 401 = 13.65v
Pl 52 = 3.3v
PL 53 = 5.21v
PL 51 =13.65v
PL 100 = +1.35V_MEN_P
PL 150 = +1.05V_MP
PL 300 =+VCC_CORE = 1.7V
PL 200 = +1.5V_RUNP

Bios PIN 8 = 3.33v

PQ 400 = D=19v...G=0v !...S= 19v
The gate here must be Low !

U46 = +3.3V_RUN/+5V_RUN present
U43 = +3.3V_ALW_PCH/+1.05V_RUN present
U45 = +3.3V_SUS/+3.3V_M present
UC3 = PCH_PLTRST#_EC = 3.3vTry to flash bios (3 chip ) same issue too !

What would i check too !!

[mcplslg123]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

Most likely PU701 is damaged. PQ400 pin4 is not connected to the charging IC here. Its Controlled by PU701. So probe PU701 voltages. This is dell latitude baby!!!

[lapfix]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

Thank you my friend.

Yes this is latitude hhhh
Ok , so if i m understand you , PQ400 Gate must be more than 0V !

PU 700 :
Pin 1 = DC_IN = 19V
Pin 7 = DC_BLK_GC = 0V
Pin 9 = P33ALW2 = 3.21v
Pin 15 = PWR_SRC =19v
Pin 18 = P33ALW = 3.3v
Pin 22 = DK_AC_OFF_EN = 3.3v
Pin 24 = ACAV_IN_NB =3.01v
Pin 27 = P50ALW = 5V
Pin 33 = DC_IN_SS = 19v

[Danyo]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

Thank you my friend.

Yes this is latitude hhhh
Ok , so if i m understand you , PQ400 Gate must be more than 0V !

PU 700 :
Pin 1 = DC_IN = 19V
Pin 7 = DC_BLK_GC = 0V
Pin 9 = P33ALW2 = 3.21v
Pin 15 = PWR_SRC =19v
Pin 18 = P33ALW = 3.3v
Pin 22 = DK_AC_OFF_EN = 3.3v
Pin 24 = ACAV_IN_NB =3.01v
Pin 27 = P50ALW = 5V
Pin 33 = DC_IN_SS = 19v

Hi, there.
I've got exactly the same problem with Dell Latitude E5540. All measurements are spot on. Have you found a solution.

[dohcom]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

Hi, i have a similar problem with a Dell Latitude E5570, The 19.5V power rail is dropping to 13.65V not far after the input and that is being maintained around the board, but i am also getting the 5V and 3.3V.
I dont think the 13.65V is correct, I will be getting the schematic soon so will have further info, and would like any feedback if possible.

[Udemzy]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

A simple thing like cleaning dried cooling paste and applying a new one can solve this kind of issues on dell.

I notice dell is a very sensitive laptop, I've solve a lot of cases like this by just applying thermal paste and sometimes reprogram the BIOS.

[Stewd]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

Hi, i have a similar problem with a Dell Latitude E5570, The 19.5V power rail is dropping to 13.65V not far after the input and that is being maintained around the board, but i am also getting the 5V and 3.3V.
I dont think the 13.65V is correct, I will be getting the schematic soon so will have further info, and would like any feedback if possible.

Hi, did you find out the problem? Same here, 13v on the main power rail but all other voltages are fine. Thanks.

[piernov]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

https://www.badcaps.net/forum/showthread.php?t=90356

[mcplslg123]

Re: Dell Latitude E5540 power On than Off after 5 seconds.

13V on main rail is absolutely fine here.Your problem may be elsewhere. read the thread linked by @piernov to know what is narrow voltage charging technology.