Dell Inspiron 15 5000 no power

[vpower]

Hi, I have this Dell Inspiron 15 5000, label says P102F and P102F002. It is completely dead, no charging lights. Any help with troubleshooting? I'm not even sure about the motherboard version, maybe the attached photos could help.
Thanks in advance
Wrong forum, sorry, how to delete or move to correct section?

[mon2]

See attached. Locate these 2 x DCin mosfets. You will need to check the voltage to ground of:

source (1-2-3)
gate (4) ; should be ~25v if all is well and the charger IC is enabling the power path to the logic board
drain (5-6-7-8)

measure both DCin mosfets. Post all measurements.

Update - the BV may not be matching yours. Checking my database for other board views to locate a suitable one..

[vpower]

See attached. Locate these 2 x DCin mosfets. You will need to check the voltage to ground of:

source (1-2-3)
gate (4) ; should be ~25v if all is well and the charger IC is enabling the power path to the logic board
drain (5-6-7-8)

measure both DCin mosfets. Post all measurements.

Update - the BV may not be matching yours. Checking my database for other board views to locate a suitable one..

I took a picture and I made a few checks with multimeter:
mosfet with white square:
source pin 1-2-3 20v
gate pin 4 3v
drain pin 5-6-7-8 20v
mosfet with red square:
source pin 1-2-3 20v
gate pin 4 15v
drain pin 5-6-7-8 20v

20v also on the first big diode and the second pin of dc-in cable.
weird thing..if I try to measure voltage on the first lower pin of the dc-in cable connector (orange arrow), a short occures (you can tell there is a little burn mark)

[vpower]

if needed, I could also measure this part of the motherboard in the attached photo

[mon2]

Share the topside markings of the mosfets (white & red squares) that you have measured in your post # 3. We need to know if they are P-channel or N-channel types.

[vpower]

thank you

[mon2]

Both of these appear to be P-channel mosfets from Alpha Omega AONR21321

AONR21321_Rev.1.0_Rohs (aosmd.com)

To avoid shorting events, better to study the circuit without power to the logic board. Locate nearby these mosfets the charger IC that is driving both of these DCin mosfets. The charger IC will usually be a black square device with pins on each side. Given that the DCin mosfets are P-channel type, the charger IC is probably NOT from Texas Instruments or the 'BQ' style. TI likes to use N-channel mosfets.

Hunt around also the other side of these mosfets. Share more pics of that area and the topside markings of the charger IC. Essentially you are reverse engineering the logic board's power path. Somewhere along the way, the power is stopping to travel to turn on the board.

[vpower]

here some pictures. please help me locate the charger ic. Maybe the one with the green dot?

[mon2]

The charger on your board is the Intersil (now Renesas) ISL9538CH

ISL9538C - Buck-Boost Narrow VDC Battery Charger with SMBus Interface | Renesas

The full datasheet is protected so sharing a pinout from my database.

[vpower]

thanks, found, is there any voltage I need to check?
ps when the motherboard is connected to the original power supply, that component is the only heating if I use my thermal camera.

[mon2]

Start with checking very carefully the ACOK pin voltage on this charger ic to ground. This line should be a logic ‘1' and perhaps about 3v3 if the power adapter is considered to be ok.

Also note the pin #1 on the chip is where there is a topside dimple and white arrow in the silk screen.

[vpower]

ACOK as pin 24 is 3.3v

[mcplslg123]

First of all mention the mb markings. Remove the stickers on the ram slot and its likely silk screened there. Link schematic,if available.

[vpower]

I have this under the ram slot

[vpower]

First of all mention the mb markings. Remove the stickers on the ram slot and its likely silk screened there. Link schematic,if available.

I think this is the motherboard:

MKB N TGL 8L MB 19861-1

KTKHP$JA

I cannot find any schematics

[vpower]

First of all mention the mb markings. Remove the stickers on the ram slot and its likely silk screened there. Link schematic,if available.

I found something https://www.badcaps.net/forum/troubl...gl-19861_19862

[vpower]

Start with checking very carefully the ACOK pin voltage on this charger ic to ground. This line should be a logic ‘1' and perhaps about 3v3 if the power adapter is considered to be ok.

Also note the pin #1 on the chip is where there is a topside dimple and white arrow in the silk screen.

it looks like the 19V_DCBATOUT line is shorted

[mon2]

With no power, measure the resistance to ground of 19V_DCBATOUT. What is the resistance?

A low resistance may be due to a shorted capacitor or a leaky mosfet on the board. If a high side leaky mosfet then the circuit that is mated with this high voltage of ~19v may be defective. If it is the CPU, the board will be a no-fix.

Would you have an adjustable power supply for power injection? If yes, dial up the power supply to 1 volt @ 3A-5A and inject this external 1 volts onto the shorted line. Monitor who is heating up.

[vpower]

With no power, measure the resistance to ground of 19V_DCBATOUT. What is the resistance?

A low resistance may be due to a shorted capacitor or a leaky mosfet on the board. If a high side leaky mosfet then the circuit that is mated with this high voltage of ~19v may be defective. If it is the CPU, the board will be a no-fix.

Would you have an adjustable power supply for power injection? If yes, dial up the power supply to 1 volt @ 3A-5A and inject this external 1 volts onto the shorted line. Monitor who is heating up.

problem solved, thank you! I spotted a shorted capacitor (PC5101) with my thermal camera while injecting voltage. thanks again for the hints.

[mon2]

Very nice ending! The updates and resolution are appreciated.