Dell XPS 15 9530 LA-9941P no power

[Conste]

Dear all,

I have a motherboard from a Dell XPS 9530 laying here which doesn't power on.
As far as I can tell I only have 1,3xx v on the power button.
No voltage at all on bios chip.

Unfortunately I do not have a battery or the original charger cable, just a universal one.

Can someone tell me how to start searching for the fault?

Schematic can be found here:

https://cdn.badcaps-static.com/pdfs/...4c3e981484.pdf

Thanks in advance.

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

Anybody?

[SMDFlea]

Re: Dell XPS 15 9530 LA-9941P no power

Start by taking voltage measurements on all large grey coils .

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

I cannot detect any voltage on coils.

/Edit: Charging coils has 13,50 volts

According to power on diagram

+3VLP is there, but not EC_ON.

How to go on?

[SMDFlea]

Re: Dell XPS 15 9530 LA-9941P no power

Press SW2 in (BATBTN#),keep it pressed in and measure voltage on EC_ON

.

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

Where to measure it?

I just suspected that I don‘t have 3,3 and 5 volts on coil because I don‘t have EC_ON.

[SMDFlea]

Re: Dell XPS 15 9530 LA-9941P no power

Where to measure it?

I just suspected that I don‘t have 3,3 and 5 volts on coil because I don‘t have EC_ON.

Yes as you can see by the IO power sequence.

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

Where is the measure point for EC_ON?

I can say that I have measured the power button wrong, I have 3,3v and goes to 0 if I press it like it should.

Thanks for your help!

SW2 has also 3,3v and goes to 0v when pressed.

[SMDFlea]

Re: Dell XPS 15 9530 LA-9941P no power

You can measure EC_ON at RE340 if you can find it,do you have the boardview?, or if not measure PU300 pin pin 6 for 3VA_EN. Also measure the voltage on pins 7,8,18 and with no power attached check the 4 mosfets PQ300 - PQ303

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

You can measure EC_ON at RE340 if you can find it,do you have the boardview?, or if not measure PU300 pin pin 6 for 3VA_EN. Also measure the voltage on pins 7,8,18 and with no power attached check the 4 mosfets PQ300 - PQ303

No, I don't have a boardview.

Thanks a lot, I will measure and tell the values tomorrow.

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

PU 300

Pin 6 = 3,254 v
Pin 7 = 0 v
Pin 8 = 0 v

Pin 18 = 0 v

MOSFETs seems okay, but PIN 4 of PQ 303 is nearly on ground! Cause could be PC314 or a defective PU 300. I think that I can see a small burn mark on PU300, but maybe it just got hot and is not defective.
I will inject 1 V and 3 amps or that way to PIN 4 of PQ 303 and see if something gets warm.

/edit: Made this test when on power supply, without power supply resistance on PIN 4 is like 144 Kohm, so not guilty?

Also saw that EN1 (Pin 20) is just like 1,4 v, EN2 (Pin6) is good...

[emestee]

Re: Dell XPS 15 9530 LA-9941P no power

This is a dell board with PS_ID, it may not want to power up if it doesnt identify the adapter through 1-wire protocol. This means the universal charger may not work.

EN1 should be 3.3v. You're saying it is 1.4v and also same on the power button. That's probably what you should be looking at.

Also note that in the internal structure of TPC51225C, the LDO outputs (pin 3 and 15) are always on. You may want to test these. If they aren't present, then the chip won't start and it's a solid indication it's dead.

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

This is a dell board with PS_ID, it may not want to power up if it doesnt identify the adapter through 1-wire protocol. This means the universal charger may not work.

EN1 should be 3.3v. You're saying it is 1.4v and also same on the power button. That's probably what you should be looking at.

Also note that in the internal structure of TPC51225C, the LDO outputs (pin 3 and 15) are always on. You may want to test these. If they aren't present, then the chip won't start and it's a solid indication it's dead.

Hello,
I managed to get some original Dell PSU, all tests were done this one.

Power button has 3,3v, the original measure was wrong.

Pin 3 and 15 do have 3,3 and 5v, everything good.

Enable 2 has 3,3v, but sw2 doesn't switch high, why?
Why is en1 only 1,4v? It comes from ec, either ec is bad or pu300?

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

unsoldered PU300 and wanted to test if 3,3 on en1 appears, PCH was getting hot, then I immediately unplugged the PSU.

Did I destroy something?

[emestee]

Re: Dell XPS 15 9530 LA-9941P no power

unsoldered PU300 and wanted to test if 3,3 on en1 appears, PCH was getting hot, then I immediately unplugged the PSU.

Did I destroy something?

Probably. You should never ever power up a board with a DC-DC converter removed. This will make MOSFET gates float, they will charge up and open, letting 19V into the output of the power supply.

[emestee]

Re: Dell XPS 15 9530 LA-9941P no power

Enable 2 has 3,3v, but sw2 doesn't switch high, why?

How do you know it doesn't? Did you put a scope on it?

Why is en1 only 1,4v? It comes from ec, either ec is bad or pu300?

Possible. You can short EN2 to EN1 and see if this powers up the 3V rail. Alternatively, pull out PR350 (or desolder the jumper), thus interrupting the EN2 line. Then you can measure it on the EC side. If the EN voltage goes to normal 3.3V, and the resistor itself is within the nominal, you have a bad TPS chip.

[mcplslg123]

Re: Dell XPS 15 9530 LA-9941P no power

unsoldered PU300 and wanted to test if 3,3 on en1 appears, PCH was getting hot, then I immediately unplugged the PSU.

Did I destroy something?

The PCH is definitely gone. Dont make such costly mistakes. Dont you know you shouldnt power a mb without 3/5V regulator in place??

[Conste]

Re: Dell XPS 15 9530 LA-9941P no power

No, unfortunately I did not know that.

Since I cannot change the PCH, the repair is finished now and I have to order a board from aliexpress