Alienware M17 R3 M/B LA-J521P charging issues

[ub6ib969]

Hi,
Alienware m17 R3 which charges using USB-C however it does not charge using PJPDC1 (dc jack)

• disconnected PJPDC1 and measured voltage on Pins 1-6 19V (19V_ADPIN)
• once connected into PJPDC1 PIN 1-6 1.20V (19V_ADPIN)
• Diagnostic tests does not detect charger.

Has anyone have this issue before?

[mon2]

What are the details of the dc jack power adapter? Alienware = Dell so most likely using the PSID 1-wire interface to identify the power adapter. Is the BIOS able to detect the power adapter? If not, the PSID is not working.

Confirm that the DCin jack is not defective.

Confirm (without power to the board) that the PSID pin of the DCin jack is mating with the PL13 ferrite bead on the logic board.

Then, attach the power adapter to this logic board and measure the voltage to ground of either side of PL13. What is the voltage?

There are many threads on this forum on this topic so do review them but often, PQ4 mosfet becomes defective or the DCin connector itself is at fault.

Be sure that you are using a true Dell brand power adapter and not a DC power supply. Only the original adapter will offer the 1-wire device to identify the power adapter's specifications.

[ub6ib969]

• It is OEM 240W Dell Power adapter
• I do not have a dc jack to check however i did measure pin1-6 and I am receiving when measure the dc jack connecter unplugged from the board.
• PSID pin of the DCin jack is mating with the PL13 confirmed.
• PIN 13 PSID 3.17v
• 0V on PL13 with the power adapter plugged in and battery unplugged.

thank you for all the help

[ub6ib969]

replaced pq4 however still does not detect a charger. It does detected a usb c charger though.

[mon2]

Missed that you lose the adapter voltage on insertion into the dcin jack. This implies a power path issue. Review the sticky above by piernov on battery charge circuits.

Trace where this adapter voltage travels. Remove all power. Measure the resistance to ground of this output rail.

With no power, test the resistance across the mosfets in the power path to the charger chip.

Measure

source & drain
source & gate
gate & drain


The unit operates ok on the usb C power adapter or when using a charged battery?

[ub6ib969]

The unit does operate fine and charges on usb c power. If usb -c is being used are the same mosfets used to the intersil IC or does it use a different path ?

[mon2]

Attach the power adapter. Measure the voltage to ground on the mosfets @ PQ12, PQ15. Measure source (1-2-3); gate (4); drain (5-6-7-8) on each mosfet. After PQ15 -> the charger IC follows. This is for the barrel jack power adapter power path.

When using the Type C adapter, it is PUS02 who passes on the VBUS voltage from this source onto the charger IC which we know works.

So the suspects are the PQ12 & P15 mosfet cluster and their driving circuits.

Post each measurement.

[ub6ib969]

thanks again for your help. i measured the following.

PQ12 1-2-3= 0v 4=0v 5-6-7-8 = 0v
PQ15 1-2-3=0.5v-0.8v 4=0v 5-6-7-8 =0v

update: removed PQ12 and receiving 19v on 1-2-3 gate.

[mon2]

Source pins = 1-2-3
gate pin = pin 4
drain pins = 5-6-7-8

If you remove PQ12, you have 19v present on the removed PQ12 pcb pads - pins 1-2-3?

Confirm that you have 19v present on each side of the emi coils @ PL8-PL12.

[ub6ib969]

don't have the same exact mosfet P-Channel EMB03P03H but can I use PZ0703EK MOSFET? almost same values.

[ub6ib969]

Source pins = 1-2-3
gate pin = pin 4
drain pins = 5-6-7-8

If you remove PQ12, you have 19v present on the removed PQ12 pcb pads - pins 1-2-3?

Confirm that you have 19v present on each side of the emi coils @ PL8-PL12.

yes when pq12 removed, pins1-2-3 receive 19v

PL8-PL12 = 19.9V on each side of the coils.

[mon2]

The other P-channel mosfet you have should be ok as a replacement for PQ12. If you solder back PQ12, the voltage on pins 1-2-3 (source) are no longer 19v? If correct, remove all power, meter in resistance mode. Measure the resistance to ground of the drain pins (5-6-7-8) on PQ12.

What are the voltage measurements to ground on the comparator @ PUS06A? The issue may be the gate driving logic that is south of the mosfet @ PQ12 in the schematics. Going cross-eyed following this spaghetti schematic.

We know that PQ12 is a P-channel. For this mosfet to enable, the gate voltage must be lower than 19v. For this to occur, the 2N7002 @ PQ8 must enable. The gate pin on PQ8 is driven by the comparator @ PUS06A pin # 1.

Post each measurement.

[ub6ib969]

- soldered back the "sus" mosfet removed and resistance to ground for pins 5-6-7-8 = 1.479v, i am now getting 19V on 5-6-7-8 Pin 1-2-3 = 19V PIN 4 = 9.4V
- PUS06A PIN 4 (GND) = 0V
- PUS06A PIN 1 = 3.2
- PQ8 PIN 1 D4_DCIN = 0V

[ub6ib969]

PQ8 without PQ12 mosfet PIN 1 =0v, PIN 2 =3.2V PIN 3 = 0v
PQ8 with PQ12 mosfet PIN 1 =0v, PIN 2 =3.2V PIN 3 = 0v

is 3.2V the correct value for PIN 2 @ PQ8? seems it is getting the same value from PUS06A pin # 1.

[ub6ib969]

update: the charger was detected and charged overnight, however but once discharged the charger was no longer detected. There is now a short to ground at PIN 2 on the PQ8 G4_DCIN @ 002.9 OHM in addition PUS801 is very hot.

removed PDB11 and PRS892 to see if the short would disappear but it still exists.

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of PUS801, pin # 3 = output of this LDO regulator.

Keep in mind that this is a LDO regulator (not a switching type). Due to this design, this part is 'burning' the very high voltage of 19v down to the output of 3v3 so yes it will produce heat in the process. The heat you are measuring may be normal for such a high voltage (input) regulator.

[ub6ib969]

PUS801, pin # 3 = 0.201V (resistance mode)

[mon2]

Can you share a pic of your meter face when measuring this? If you are truly in resistance mode, then the measurement will be in ohms. If in DC volts mode, then the measurement will be in volts (V).

We need to confirm the meter setting and also the LCD screen display units of measurements.

[ub6ib969]

thank you for taking all this time. appreciate all the help.

picture uploaded.

black probe on ground and red probe on pin 3 of pus801

[rogfanther]

These measurements are with the suspect PQ12 soldered on the board, right ?

Please, set the meter in Ohms ( about two positions turning clockwise on your meter ) and measure

source to drain
source to gate
gate to drain

as pointed by mon2 above.