Dell Inspirion 5520 no power

[hazardus]

Hi all.

My dell inspirion just stopped working. No power.
I checked the two P-channel mosfet on the DC-IN side.

There is no short. On the first MOSFET PQ100 I've 18V but after the second
MOSFET PQ101 I have almost nothing 0.7V. I checked it for short, but no short.
What should I check next?

Thanks.

[samanthban]

Re: Dell Inspirion 5520 no power

if voltage available at pin 123 of pq100 check pq 101 gate components. if no voltage at pq 100 check gate components.

[razu]

Re: Dell Inspirion 5520 no power

Short the 0.7V mosfet Without Gate. pin 1,2,3 and 5,6,7,8 its might be okkkk..

[hazardus]

Re: Dell Inspirion 5520 no power

if voltage available at pin 123 of pq100 check pq 101 gate components. if no voltage at pq 100 check gate components.

I've charger voltage on PQ100 at pin 1,2,3.
The gate has the charger voltage for some reason.
As far as I can see PQ100 and PQ101 shares the same gate. No voltage divider.

Short the 0.7V mosfet Without Gate. pin 1,2,3 and 5,6,7,8 its might be okkkk..

Yes, If I short those pins it's working. What could be the problem?

[razu]

Re: Dell Inspirion 5520 no power

you can short those pin with a fuse .......and return to the customer.......

[kiraro]

Re: Dell Inspirion 5520 no power

Check acin voltage on charger circuit it should be 3,3v if 0v the charger circuit can't switch second MOSFET ,I have a similar problem last week and it was missing a acin voltage (because broken resistance ).

[hazardus]

Re: Dell Inspirion 5520 no power

Check acin voltage on charger circuit it should be 3,3v if 0v the charger circuit can't switch second MOSFET ,I have a similar problem last week and it was missing a acin voltage (because broken resistance ).

ACIN is 3.3V at pin 2. ACOK is 1.2V at pin 13.
I've DCIN voltage at the charger ic.

[subroto]

Re: Dell Inspirion 5520 no power

Change the PQ101 P-channel MOSFET. If not work then add a feedback resistor of 1k between PQ100 output and gate of PQ101.
Your problem will be solve.

[hazardus]

Re: Dell Inspirion 5520 no power

Change the PQ101 P-channel MOSFET. If not work then add a feedback resistor of 1k between PQ100 output and gate of PQ101.
Your problem will be solve.

I changed the mosfet with different type of P Channel mosfets, but none of them are working.

Do you mean put a 1k resistor between the gate of PQ100 and PQ101?
Because there is a feedback resistor between the source and gate and it reads fine in the circuit.

[subroto]

Re: Dell Inspirion 5520 no power

The source of PQ100 is connected with charger Positive voltage, most of the cases a feedback resistor off 100K is connected between the source and gate of first MOSFET. Then the second MOSFET PQ101 drain is connected with the drain of PQ100. If the PQ101 gate has no voltage then PQ101 will be off and no voltage is in DCBATOUT.
Now you can do anyone of the following

i) Remove PQ101 and simply short the source and drain.
ii) Join the gate of PQ101 with rhe gate of PQ100 by a piece of wire.
iii) Add a feedback resistor of 1k or 100k(most preferable) between drain and gate of PQ101

But the first one is easy method and less time consuming.

[kiraro]

Re: Dell Inspirion 5520 no power

ACOK must be 0V ,short it with ground and you will find 5v and 3.3 v (always) coming .