Vostro 3401 strange problem charge

[the Benninger]

Now the one offering apologies is me, I was working on the bottom side, when I looked at this part that you pointed out, I noticed the marker that is above PQ1 and not in PL3. The aggravating factor is that it was on the inductive coil PL301 on the bottom side, regarding the resistor PR1=33.2 ohms on my multimeter

the measurements of PQ1 are

Source/Drain= 65.2k
Source/Gate= 12.48k
Gate/Drain= 73.5k

[the Benninger]

I have no way of knowing if pq1 is good or not so I have made the decision to change it, while the resistance PR1 is at its correct value, which leads me to think that it is pq1 that causes the source to disassemble when reconnecting.
If you have anything else to add, I would be grateful; if not, we will just wait for the arrival of the components.

[mon2]

These are very low resistance readings for a good mosfet:

Source/Drain= 65.2k
Source/Gate= 12.48k
Gate/Drain= 73.5k

Each should be hundreds of k ohms or higher. One reason could be the influence of other parts on the part so best to remove and then test the same mosfet while it is on your workbench. If the resistance readings remain low, the part is indeed defective. Curious on the measurements of this mosfet that has been removed.

reference reading:
https://electronicsbeliever.com/how-...-defective/

[the Benninger]

disassembled or out of the motherboard the readings were as follows

Source/Drain=72k
Source/Gate = 750M
Gate/Drain = 1050M

[mon2]

Reverse the meter leads and test source / drain but to me, this part is defective from the low resistance.

Source/Drain=72k

[the Benninger]

happy start of the week
something happens that I don't know if it's normal, when the reading started (38Mhom) it increased until it reached 60Mhom, in a span of 1 minute. I think it would have continued to increase if I hadn't lost connection. It's difficult to keep the test probes on the pins when it's disassembled due to the shape and size.

[the Benninger]

hello I bring news around here, replace the PU301 in addition to PQ1, the new thing is that it is no longer heating, but the machine still does not turn on, not even the charging LED
I made some readings that I attached in the image, when I made the mistake of incorrectly bridging on the coil (PL301) is when I immediately lost it, so the question is do you know which other component suffered from this?

[Sephir0th]

Voltage measurements are usually less than half of the picture you need.

Measure resistance to GND of Pin 9, 11, 12, 17 and 20 and share the readings here.

PS: it's still puzzling how the PU301 has failed this bad. Normally nothing bad should happen when connecting a 3V supply to a signal which is supposed to be supplied with 3V too. At least not with such serious damage.

[teccyber-lab]

Hi Sephir0th I'm writing from another account, I can't use my computer anymore. I decided to copy the client's data to my mother card, that's why I couldn't use my computer anymore. the sense of responsibility is very strong

While I did a reading of PU301 as you asked, I hope you can fix this Mobo because it would be the one I'm going to use. If I can fix it, of course, here are the results of the ground resistance measurements, and the voltage reading when the plava is energized. I await your guidance.

[mon2]

From pins 17 & 18 on PU301 - the +3VALWP is shorted.

Locate a solder blob @ PJP302. This blob shorts +3VALWP to +3VALW. Remove this solder short and then measure the resistance to ground on PL301. No power to the board during this test. Is PL301 still 10R9 ohms to ground?

[teccyber-lab]

hI mon2 I have the new readings

pin	hom	volts	WIHTOUT-PJP302
1	1~1.5M	4.3	2.2M
2	500k	19.4	10M
3	500k	19.4	10M
4	500k	19.4	10M
5	500k	19.4	10M
6	10.9	9mv	44K
7	0.2	0	0.2
8	0.2	0	0.2
9	10k	105mv	54K
10	---	125mv	0.L
11	125	462mv	130K
12	2k	457mv	1920K
13	0.75	330mv	0.670M
14	10.9	4.5mv	40K
15	10.9	179mv	40K
16	46k	6.6mv	47K
17	46k	6.6mv	155K
18	0.2	0	0.4
19	10.9	54~90mv	39K
20	10.9	54~90mv	39K

[mon2]

So the regulator is not shorted but downstream consumer side is. Measure the resistance from the solder blob to the pch 3v3 rail. The pch uses the same power rail. It is possible the cpu is dead from this event but to be determined.

[teccyber-lab]

Good morning mom2, I don't know how to reference PCH 3v3, don't have the boardview for this board, however I read the ground to everything surrounding PJP302, intuitively it takes me to UZ2

[mon2]

Pour some alcohol on the top surface of UZ2. This will enhance the markings. Then take a clear pic of the top surface. What are the markings? The very large PCB traces hints that the same rail is being shared by a device that consumes heavy currents. Where does this area lead to?

[teccyber-lab]

PU301 overheats

[mon2]

If PU301 is overheating, remove all power. Meter in resistance mode. Measure the resistance to ground of each output rail on this device.

[teccyber-lab]

PIN	ToGND
1-BS	100k~141k
2~5	210k
6	10.7hom
7+8	000.4
9	9.90k
10	900m
11	110k
12	1965k
13	170k
14	12.3hom
15	0.960m~1500m
16+17	1744hom
18	000.2hom
19+20	10.7hom

[mon2]

Can you confirm if the solder blob @ PJP302 is open or is it closed with solder?

[teccyber-lab]

close

[mon2]

Open this solder blob and confirm if the short remains on pins 19 & 20.