Dell Vostro 3360 no power on

[bicalov]

Hi
I have a vostro 3360 which don't start.
On the motherboard I found PQ10 to get very hot, but the components connected to him seems to be OK, no short
Is this a defective PQ10 for sure or do I have to look at other things?

[atsio]

Re: Dell Vostro 3360 no power on

You will never know unless you remove it and test it.

[bicalov]

Re: Dell Vostro 3360 no power on

Thx atsio.
I have to wait a while to do that because I have to order the part. In my area it have no electronics shops who carry smd chips.

[atsio]

Re: Dell Vostro 3360 no power on

You remove it, you test it, check on board that there is no short and then solder new one.

[HarryPK]

Re: Dell Vostro 3360 no power on

Its look like bad diode...

[bicalov]

Re: Dell Vostro 3360 no power on

Hi Guys,
I put a new PQ10 on the board, but this one also gets very hot, so no gain there.
Checked around the PQ10 for other components , but no short there.
There is a strange thing, the mosfets are usually numbered 1-2-3- or G-S -D. There are several 2n7002W but the marking on the board says I-G-O.which does not correspondent with the factory specs from the 2N7002W.
The schematics shows 1-2-3 of which 1 is on GND and on the board 2 is on ground.
Can somebody pls explain how to messure?

[samanthban]

Re: Dell Vostro 3360 no power on

mosfet can be easily identified by removing it .n channel single or dual , p channel single or dual.there is a short/falty that's what component getting hot

[bicalov]

Re: Dell Vostro 3360 no power on

mosfet can be easily identified by removing it .n channel single or dual , p channel single or dual.there is a short/falty that's what component getting hot

Thank you, that I understand, but the issue remains about the markings on the mobo, how to interpreted that.

[bicalov]

Re: Dell Vostro 3360 no power on

Wat it looks like, is that Dell uses the marking "In- Out-GND" on the motherboard,
This is very confusing, because the schematics use "1-2-3"
The pinout from the 2N7002W is 1= Gate, 2= Source and 3= Drain
So on the mobo it looks like In=Gate, Gnd=Source and Out=Drain
The schematics now look wrong because 1=Source, 2=Gate and 3=Drain and 2 is on gnd

[ktmmotocross]

Re: Dell Vostro 3360 no power on

replace both two mosfets if it is a step-down circuit.

[atsio]

Re: Dell Vostro 3360 no power on

Probably you got the wrong numbering (if I am looking at the right schematic). PQ10 is an 4435. 2n7002W is either the PQ11, PQ1, PQ14 or PQ16.

[bicalov]

Re: Dell Vostro 3360 no power on

That is correct. The PQ10 I have changed for a new one. The PQ11,-1,-14,-16 are 2n7002W and it is by these ones the letters I,G,and O are on the board and not 1-2-3.
If I translate the letters from the board to the schematic, it would be: 1= I , 2 = G and 3 = O. or translated to letters Gate=I, Source= G and Drain= O.
Very confusing, see pictures

[atsio]

Re: Dell Vostro 3360 no power on

Just remove pq10 again and check resistance relative to ground on pads (on motherboard) 1, 4 and 8.

[bicalov]

Re: Dell Vostro 3360 no power on

pq10 removed.
pin 1-2-3= 286k
pin 4= 47,5k
pin 5-6-7-8= 152k

[atsio]

Re: Dell Vostro 3360 no power on

152k means there is a problem somewhere down the line (but it's not so clear). Do you have a lab supply? Check resistance relative to ground on coils, PL1, PL2, PL3, PL4, PL5, PL6, PL7, PL8, PL9.

[bicalov]

Re: Dell Vostro 3360 no power on

I do not have lab supply, I do have a 120W adapter which can stand a short cut.
PL1= 380 ohm
PL2= 10.8 ohm
PL3= 2,9 ohm
PL4= 9,2 ohm
PL5= 42 kohm, starts at 850 kohm and drops to 42 kohm. Capacitor unloading?
PL6= 22,6 ohm
PL7= 1,6 ohm
PL8= 492 ohm
PL9= 192 kohm

[atsio]

Re: Dell Vostro 3360 no power on

You have problems on the 3.3v_alw rail as well as on the gfx_core rail. Remove pr133 and check resistance relative to ground on both pads.

[bicalov]

Re: Dell Vostro 3360 no power on

Sorry, I can't find PR133. I looked for more than an hour and I can find all the components in that part of the schematics, except for the PR133.
Also I forgot to mention that I took PU7 off the board to replace it. I waited to measure first before I put it back on. Do I have to put it now or wait

[atsio]

Re: Dell Vostro 3360 no power on

remove pl6 and measure

[bicalov]

Re: Dell Vostro 3360 no power on

PL6-1 = 1,2 Mohm
PL6-2 = 22,6 ohm