Dell inspiron 3542 laptop not powering up

[Omron]

Hello guys, I have issue with Dell Inspiron 3542 Laptop, motherboard name "CEDAR_INTEL_MB 13269-1 PWB FX3MC REV A00"
On power button it came on then fans were spinning but no image.

After my work laptop isn't doing anything, no light coming on, when I press power button
I checked voltage on charging port it has 19.5 volts

I saw video on youtube and tried to bridge with wire mosfets on image, it gave me picture but soon it stopped working
after I decided to soldier another mosfets and I was getting deeper and deeper in mud the more I worked on motherboard.

Is this thing repairable or not?
Padding for mosfet is gone now

I don't have knowledge to diagnose what is wrong unfortunately, but I'm willing to do everything if someone would give me aid, I would be very thankful :3

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Q2402/2403 is PSL logic and often fails on this motherboard. Search for boardview in this forum.its posted here. You can easily connect a wire from Gate of Q2403 to PR2433,pin2. It'll be clear to you once you open the boardview.
Q2403 is N channel mosfet(2N7002K)
Q2402 is P channel mosfet(DMP2130L)

Usually Q2402 fails and you can remove Q3004 from this board and place it at Q2402.

Carry out these steps and hopefully it can be fixed. have some patience and practice some YOGA before doing the job as you seems to be stressed.

[memoslar]

that worked for me! thanks!!

[Omron]

Re: Dell inspiron 3542 laptop not powering up

Thank you so much for trying to help me!

So if I understood you correctly, it should be like this?

In my board view its called "R2433", I have one more question, when I removed the original mosfets I replaced them with same size from my old dead gpu, I didn't know that mosfets can be different types, should I order new mosfets both of them and replace with fresh ones? And I can leave Q3004 intact that way

I am very confused why laptop doesn't even turn on lamp on when I try to power it, before it gave some signs of life, now nothing, I just hope I didn't bridge something too badly and that I didn't burn chipset or something,

Before I do anything I just wanted to hear your confirmation first, I uploaded the picture below

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

We need to complete these steps first and only after that we can make further checks. You have understood correctly. Q2402-You can remove Q3004 and place it at its place. Q2403 is n channel and is available plenty on scrap boards. If you have some scrap boards, then look for mosfets maked K72/S72 and if you get one, just replace it. Else ,you need to order it.

PS: Yes ,its R2433 and not PR2433

[Omron]

Re: Dell inspiron 3542 laptop not powering up

I was searching online, I found:
"Q2403 is N channel mosfet(2N7002K)"
https://www.belielektronik.rs/2N7002-TRANZISTOR

This one I cannot find:
Q2402 is P channel mosfet(DMP2130L)
So if I unsolder it from Q3004 and put it on Q2402
will motherboard still be functional? Mainly because Q3004 will be empty

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Yes, Mb will be functional while Q3004 is removed.

[Omron]

Re: Dell inspiron 3542 laptop not powering up

Excellent, I'll order 2N7002 then, and will reply once its here and all soldered

[Omron]

Re: Dell inspiron 3542 laptop not powering up

I soldered Q2402 from Q3004
And soldered new 2N7002K and made a wire from Q2403 to R2433

Laptop came on, I kept it on like 5-10 minutes it stayed on, but I noticed laptop lamp was not on, before I assemble everything back together, I tried to turn off/on laptop 1 more time and now it has Light ON then it Dims and it goes off, no screen again. But at least its making some signs of life like before. Now I'm at start again basically, it was quite hard to solder these, I did it one by one and took pauses in between

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

This again is a common problem on this platform. Measure voltage on all pins of LIDSW1.Its located near hdmi port.Pin2-3 should be 3.3V,pin1 should be zero. If its not so,then remove LIDSW1 and measure pin2-3 again.

This problem can be solved-so have patience.

[Omron]

Re: Dell inspiron 3542 laptop not powering up

Yes I'm patient, not doing anything without you anymore

PIN 1 LIDSW1 = 0v
PIN 2 LIDSW1 = 3.42v
PIN 3 LIDSW1 = 3.42v

Seems to show okay results

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Voltage on pin 1/4/20/21 (after turning on) on LCD connector.? Avoid measuring directly on connector and look at boardview for any test point where you can measure easily.

Yes, LIDSW# is working as expected.

[Omron]

Re: Dell inspiron 3542 laptop not powering up

pin 1 = 19.5volts

pin 4 = 0 volts

pin 20 = 0 volts

pin 21 = it was 3.3 volts when screen came on, but I tried again and screen didnt came on and it was 0 volts this time.

Something is fishy with 3.3v line when its getting it screen comes on, when there is no 3.3v no screen on,
question would be why sometimes there is 3.3v and sometimes there are no 3.3v?

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Nothing fishy there-screen will light up when all its requirements are met. First,focus on pin4-why LCDVDD is missing. Measure voltage on U5201,pin 1-3-4 and report back.

[Omron]

Re: Dell inspiron 3542 laptop not powering up

Understood!

Pin1 = 0 volts, When screen turned on (sometimes) it was 3.34v otherwise 0v
Pin3 = 0 volts, When screen turned on (sometimes) it was 3.34v otherwise 0v
Pin4 = 3.39 volts (even when screen was not showing, it still kept 3.39v)

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

U5201 pin1 is ENable for this to output any volatge on pin3-so the anable must be there always. Pin1 is connected to D5201.So measure voltage on all pins of D5201. This may turn out to be KBC fault. Have you examined the board for corrossion under microscope/magnifying glass?

[Omron]

Re: Dell inspiron 3542 laptop not powering up

U5201 Pin1,2,3 = 0v
I don't see any signs of corrosion, laptop never left my home it was always in my room, I can brush board with isopropyl alcohol if that would help something;
I put my finger around the board to check for heating when I plug in charger, CPU and GPU chip was getting hot, they work, we are missing 3.3v Line I would say, what can cause 3.3v line to be missing?

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Replace PT4501/PT4502 caps by 330 uF tantalum caps.

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

Also check when you have no voltage on D5201 pins, is there 3.3V available on PL4502 coil.

[Omron]

Re: Dell inspiron 3542 laptop not powering up

Also check when you have no voltage on D5201 pins, is there 3.3V available on PL4502 coil.

I have voltage on PL4502 Coil, 3.4~ volts on both pins. When no voltage on D5201.

I measured PL4501 it was 5.2V~ (took the freedom while I was there)

I also measured PT4501 capacitor = 5.2volts
PT4502 capacitor = 3.42 volts

When no voltage on D5201

Visually inspecting capacitors they don`t look like they have bulge, but of course they might not hold capacitive as they should.

[mcplslg123]

Re: Dell inspiron 3542 laptop not powering up

I'm sorry but no voltage on D5201 indicates SOC failure(PCH Part). EDP_VDD_EN comes directly from SOC and if it is coming up intermittently,thats a PCH fault. So end of road perhaps for you as you may not have necessary skills/tools to replace the SOC. You can ask others for opinion.

PS: Just gave up on lenovo LA-E541P with exact same fault-intermittent display. When no display LCDVDD/PCH_ENVDD/ENBKL/BKOFF# are missing. There are no components in between PCH and JEDP1(except for LCDVDD) as all components are marked@. So its SOC fault. I've faced such SOC fault on many occassions but usually on 8th gen onwards. All the basics like LIDSW#/LCDVDD requirements were thoroughly checked before my conclusion.