Dell Inspiron N5110 3.3v present but not on power button

[s_henya]

Hi Guys,

appriciate your opinion on this weird case.

laptop is working. but 3.3v is missing on power button.

on 3.3 power supply i have voltage and on bios chip.

if i take off the cmos battery the laptop auto turn on and works.

i think this laptop had water damage and dc jack replacement before.

i know the basic concept that 3.3 should be present on power button and on press reduce to 0 and then being read by super io chip and turn on.

any idea?

[peste]

Re: Dell Inspiron N5110 3.3v present but not on power button

Hi Guys,

appriciate your opinion on this weird case.

laptop is working. but 3.3v is missing on power button.

on 3.3 power supply i have voltage and on bios chip.

if i take off the cmos battery the laptop auto turn on and works.

i think this laptop had water damage and dc jack replacement before.

i know the basic concept that 3.3 should be present on power button and on press reduce to 0 and then being read by super io chip and turn on.

any idea?

check the ribbon between the start button and the motherboard.

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

check the ribbon between the start button and the motherboard.

I check the voltage on the mainboard.
Counting from the left side
Pin 1-2 are 5v when laptop is on
Pin 3 should be 3.3 but shows 0. But not shorted to gnd
Pin 4 is gnd

Looks like something is lost on the way from the 3.3 line

Any ideas or schematics?

[miyagik]

Re: Dell Inspiron N5110 3.3v present but not on power button

I check the voltage on the mainboard.
Counting from the left side
Pin 1-2 are 5v when laptop is on
Pin 3 should be 3.3 but shows 0. But not shorted to gnd
Pin 4 is gnd

Looks like something is lost on the way from the 3.3 line

Any ideas or schematics?

You have a problem over there!
There must be only 3.3v no 5v in any pins
Do you have the board no.? here is a picture about the pwon circuit.

I found one schematic, here it is my friend!

[mcplslg123]

Re: Dell Inspiron N5110 3.3v present but not on power button

WRONG. 5V is correct on pin 3-4(what @s_henya is counting as pin 1-2). Pin2 should have 2.4V approx. This mb has nuvoton sio and it has PSL Logic involved. So pwrbtn will not have 3.3V but should be 2.4-2.5V. On page 27, PSL logic is described. Start from there.

[mcplslg123]

Re: Dell Inspiron N5110 3.3v present but not on power button

Sorry, Just read the entire post. You have 3V ALW on coil-so PSL logic is fine. No need to poke there. It has to be something wrong with RTC circuit.What is the voltage on G2101 Pad with RTC cell inserted?Check Q6001/Q6002 pins voltage.However, 5V on pwrbtn connector on pin3-4 is correct. So dont mess with it.

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

Sorry, Just read the entire post. You have 3V ALW on coil-so PSL logic is fine. No need to poke there. It has to be something wrong with RTC circuit.What is the voltage on G2101 Pad with RTC cell inserted?Check Q6001/Q6002 pins voltage.However, 5V on pwrbtn connector on pin3-4 is correct. So dont mess with it.

Thanks for your reply,
i didn't find G2101 what is it?

for the other measurements:

Q6001: (S43)
pin1 3.197
pin2 3.028
pin3 3.357

Q6002: (K72)
pin1 0 short to gnd
pin2 3.028
pin3 0 short to gnd

so something is wrong with Q6002, should i try to replace it?
i have no idea what is that transistor is, pin configuration, voltage and amps.

i do have alot of spare boards, but i don't have the exact board to salvage.

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

You have a problem over there!
There must be only 3.3v no 5v in any pins
Do you have the board no.? here is a picture about the pwon circuit.

I found one schematic, here it is my friend!

Thank you for the schematic

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

I check the voltage on the mainboard.
Counting from the left side
Pin 1-2 are 5v when laptop is on
Pin 3 should be 3.3 but shows 0. But not shorted to gnd
Pin 4 is gnd

Looks like something is lost on the way from the 3.3 line

Any ideas or schematics?

pin 1-2 has 2.7v not 5v sorry...
but pin 3 has 0v not shorted

[mcplslg123]

Re: Dell Inspiron N5110 3.3v present but not on power button

Did you checked R6006?? Remove Q6002 and measure resistance on mb pads. Perhaps you are getting voltage at the gate pin. Source is ground anyway. Drain is grounded as well which i think is wrong. Q6002 is N channel fet 2N7002K. You can search this code on other scrap boards with schematics to get one. G2101 is your RTCrst# pad. Its important to find it out.

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

Did you checked R6006?? Remove Q6002 and measure resistance on mb pads. Perhaps you are getting voltage at the gate pin. Source is ground anyway. Drain is grounded as well which i think is wrong. Q6002 is N channel fet 2N7002K. You can search this code on other scrap boards with schematics to get one. G2101 is your RTCrst# pad. Its important to find it out.

Thank you for the help, i will try this evening and update.
Btw where did u get the info for that mosfet?

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

i removed the mosfet but the pads are still shorted,
i couldn't find the part of the circuit in the schematics.

i also tried to inject 2v to the pin on the power button to see what is getting hot, but no current was drawn,.
i can do the same on the mosfet pins, but i don't know which pin should go where without schematics.

[kodox]

Re: Dell Inspiron N5110 3.3v present but not on power button

i had experienced same symptom but on two unit of acer mainboard, the culprit was the small capacitor near power button. it's not shorted but when voltage applied the voltage gone. hope this help

[s_henya]

Re: Dell Inspiron N5110 3.3v present but not on power button

i had experienced same symptom but on two unit of acer mainboard, the culprit was the small capacitor near power button. it's not shorted but when voltage applied the voltage gone. hope this help

i have a small resistor there, no cap in that area.