Dell laptop model PP24L won't start from ac adapter

[mikey5791]

Dear all,

Bought this used Dell laptop PP24L(studio 1435) in Jan 2022. It was running smooth on 64 bit Windows 7 pro from processor Intel core Duo T6400@2Ghz with 2GB RAM. The laptop battery was charging and working fine until few months back the opening screen will display something like "replacing the battery warning", press F1 to continue. Normally i press F1, the laptop will proceed to Windows and i can use as normal.

But last week, after i pressed F1, the laptop just shut down. I suspected the laptop battery is dead. So i pulled out the battery and measured the dc voltage. It was 11.7vdc. Then i plugged in the original Dell ac adapter, pressed on power button but the laptop won't start.

Fyi, i opened the laptop back casing and do not see anything with burnt smell. This is my first time opening the laptop case and do not have any experience on repairing it. However, i wish to learn how to diagnose and possibly repair it. I hope there are forum members with experience and patience can kindly guide me on this. Thank you in advance.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

Laptop repair is a skilled business, so some basic understanding of elctronics is a must to proceed.

We can help you as long as you can answer correctly and follow the suggestions.

To begin with ,you need to take the motherboard apart from the casing and visually inspect for any damage/corrossion etc.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

Laptop repair is a skilled business, so some basic understanding of elctronics is a must to proceed.

We can help you as long as you can answer correctly and follow the suggestions.

To begin with ,you need to take the motherboard apart from the casing and visually inspect for any damage/corrossion etc.

Thank you for reply. I had taken the motherboard apart from the casing but i don't notice any damage / corrosion. If i am not mistaken, the board number seems like Dell DZ1 UMA M/B, 08217-1, 48.4AR03.011

Looking forward to your kind suggestions and to diagnose.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

https://www.alisaler.com/dell-studio...a00-schematic/

Download the schematic from above link.

Measure voltage on pin1/4/8 of PQ6304. Measure resistance on PR6302(Meter set to highest scale). resistance should be measured without any power source connected.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

Done download the schematic.
As per page 63 of schematic on power charger, PQ6304 is the 8 pin P channel 30v mosfet. Sorry i can' t figure out which corner is the pin 1 and which pin is pin 8. But i did put my DMM black probe on one of the ground screw point, and my red probe on all 4 corners of the 8 pin mosfet while power on from ac adapter. There is no dc voltage on any corner. Hope i am doing this right.

On the other hand i am unable to locate which item is the PR6302 on my board. Is it a 4 pin resistor of black color very near to PQ6304? I am attaching some close up pictures for your reference. Hope this helps. Thank you for your patience in helping out.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

Was meter set to voltage settings?? You should get voltage on some pins atleast of PQ6304. PR6302 is 2 leg resistor and may be located on the other side of the board. You need to take the motherboard out of housing. Btw, you are sure your adapter is fine? If you have another dell original adapter, try with that.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

Was meter set to voltage settings?? You should get voltage on some pins atleast of PQ6304. PR6302 is 2 leg resistor and may be located on the other side of the board. You need to take the motherboard out of housing. Btw, you are sure your adapter is fine? If you have another dell original adapter, try with that.

Yes, the meter was on dc voltage setting. On PQ6304, i am not sure which one is pin 1. If i take the the pin on lower right corner nearest to no.4 of 4835 (PQ6304) as pin 1, i got dc 19.5v. And pin 4 and pin 8 are both also 19.5vdc . I flipped the other side of the board and can't seem to find any 2 leg resistor. So i think the 2 leg resistor seem to be next to PQ6304 (on the right hand side of PQ6304). Please correct me if i am wrong.
Setting my dmm to highest resistance scale of 2M and i probe on both side of the resistor. The reading is 0.00. (strange my dmm register this reading?). Fyi, i tested a 1M resistor on my dmm and it reads about 1.3M ohm. Btw, i had taken the motherboard out of the casing. I retested my original Dell adapter for working condition. It reads 19.5vdc on output.
Hope you can continue to guide and give suggestions. Thank you.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

I've marked pin1 with an arrow. Pin1-2-3 are together.Similarly pin5-6-7-8 are together on the opposite side of pin 1-2-3. Pin4 is not connected with any other pin. Hope its clear to you now. Else ,just doenload the datasheet of that mosfet and you will have clear understanding of pins. I dont see the CLR in your pic. Give pic on the opposite side.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

Sorry forgot to attach image

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter



datasheet for the mosfet

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

I've marked pin1 with an arrow. Pin1-2-3 are together.Similarly pin5-6-7-8 are together on the opposite side of pin 1-2-3. Pin4 is not connected with any other pin. Hope its clear to you now. Else ,just doenload the datasheet of that mosfet and you will have clear understanding of pins. I dont see the CLR in your pic. Give pic on the opposite side.

With my dmm black probe on the nearest screw ground, my red probe on pin 1(as per your arrow) my dmm reading is 20.4 vdc while pin 4 is at 3.2vdc and pin 8 is at 20.4vdc. Fyi, i also can't locate the CLR on my board. I had attached a picture on the opposite side of the board.
Hope you can continue with your help and suggestions. Thank you.

[mon2]

Re: Dell laptop model PP24L won't start from ac adapter

Post a pic of the bottom side. The parts of interest may be on the opposite side or are being hidden by the large heat sink.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

In post#8, i asked for image on the oppsite side but he has not shared yet. Btw, PQ6304 readings are good.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

Post a pic of the bottom side. The parts of interest may be on the opposite side or are being hidden by the large heat sink.

Attaching pictures of the bottom side and area hidden by the large heat sink. Please do request or correct me if i had done it wrong. Thank you.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

In post#8, i asked for image on the oppsite side but he has not shared yet. Btw, PQ6304 readings are good.

Attaching image on the opposite site (of PQ6304?) by removing the fan. Hope i am doing it right this time. Correct me if i am wrong. Thank you.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

R010 may be the CLR

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

R010 may be the CLR

May i know what type of testing do i need to perform on the resistor R010. Btw, I did resistance measurement on scale 200 ohm and R010 reads about 9.6 ohm.
And what is the CLR stand for?

[mon2]

Re: Dell laptop model PP24L won't start from ac adapter

CLR = current limit resistor which is technically a current sense resistor.

A low resistance value is used to gauge the voltage drop across the pins to determine how much current is being consumed on the same power rail.

The charger IC will monitor the voltage going INTO the current sense resistor and the voltage LEAVING the part and from the small voltage drop, calculate the current consumption of the rail.

If the current draw is out of spec, it will turn OFF the linked mosfets to prevent damage (in an ideal world).

The resistance of this part sounds high to me -> often such parts are very low in resistance values. Can you confirm that your meter shows 0 ohms if the leads are shorted? Be sure to use the lowest scale on your meter and remove all power. Then measure again.

[mcplslg123]

Re: Dell laptop model PP24L won't start from ac adapter

May i know what type of testing do i need to perform on the resistor R010. Btw, I did resistance measurement on scale 200 ohm and R010 reads about 9.6 ohm.
And what is the CLR stand for?

Put black probe to GND, Red probe on any pin of CLR-what is the resistance? You measure resistance to GND this way and not across the pads of CLR.That will measure resistance of the resistor itself.

[mikey5791]

Re: Dell laptop model PP24L won't start from ac adapter

Hi mon2,
Appreciate your clear explanation on the CLR.
Yes, my dmm shows 0 ohm if both leads are shorted. By setting my dmm to lowest scale at 200 ohm, while black probe to ground and red probe on any pin of CLR, i got reading of "1" infinity.

Hi mcplslg123,
I measured the resistance as per your suggestion and i remeasured using another dmm also at lowest scale of 200 ohm. The reading is at "1" infinity.