LA-D993P No power no charging

[tipoti]

hello
When you press the power button, the light turns on and off. It was working normally until a day ago. +3VALW ,+5VALW and power_sw have 5 volts, won't charge and won't turn on

P65F
LA-D993P REV 1.0

[mon2]

Re: LA-D993P No power no charging

After the lights turn OFF - do you still have the +3VALW ,+5VALW and power_sw voltages?

Are you using the original and official power adapter ?

[tipoti]

Re: LA-D993P No power no charging

it was working with non original charger. The battery was not installed. When I arrived in the morning, I noticed that the device was not turning on. I tried with another original charger and it still didn't turn on.

+3VALW ,+5VALW and power_sw 3 volts have

[mon2]

Re: LA-D993P No power no charging

See attached.

1) Start with the charger IC @ PU300.

Attach a known good power adapter -> meter in DC volts scale (30v or higher).

Carefully (!) measure the voltage of each of the highlighted IC pins.

Interested in:

Vcc (pin #28)
REGN (pin # 24)
ACDET (pin # 6)
ACOK (pin # 5)
ACDRV (pin # 4)

Post each measurement.


2) Next, remove all power / no battery.

Meter in resistance mode -> check the resistance across the mosfet pins:

PQ306 & PQ302

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each resistance measurement and the scale used on your meter for the checks. As per above sticky from @Pienov - often the 2nd mosfet gets damaged.

reference:
http://electronicsbeliever.com/how-t...-is-defective/
* see the section on resistance checks

[tipoti]

Re: LA-D993P No power no charging

Vcc (pin #28) = 19.7 Voltage
REGN (pin # 24) = 6 Voltage
ACDET (pin # 6) ACOK ( = 2.7 Voltage
pin # 5) = 3.3 Voltage
ACDRV (pin # 4) = 25.8 Voltage


PQ306 diod mode : 0.465 /
source (1-2-3) & drain (5-6-7-8) = resistance mode :465 ohm
source (1-2-3) & gate (4) = resistance mode :611ohm
gate (4) & drain (5-6-7-8) = ---

PQ302 diod mode : 0.513 /
source (1-2-3) & drain (5-6-7-8) = resistance mode :513ohm
source (1-2-3) & gate (4) = resistance mode :606 ohm
gate (4) & drain (5-6-7-8) = ---

[mon2]

Re: LA-D993P No power no charging

1) Charger IC voltages look good.

2) The mosfet resistance readings are not ok if the readings are indeed in ohms.

3) Remove all power and with flux and hot air, remove PQ302 off the board. Careful of the air pressure so that other tiny nearby parts do not go flying.

Then wait for the removed mosfet to cool and check the resistance in the same way of the part that you have removed.

Is the removed mosfet still with these very low readings?

Also check the resistance values of the PQ306 mosfet (now that PQ302 is off the board and should not influence the measurements).

[tipoti]

Re: LA-D993P No power no charging

sorry
I typed wrong kΩ

https://we.tl/t-cfstD6JZ3t

[mon2]

Re: LA-D993P No power no charging

Then the resistance appears to be ok for the mosfets.

Before placing the mosfet back onto the board, check the resistance to ground of the removed mosfet pads:

source (1-2-3)
gate (4)
drain (5-6-7-8)

if the power is not remaining ON for the main power rail then you may have an excessive current draw which is being sensed -> could be a broken current sense circuit which will result in the same observation. Or the bios of the EC controller may need to be reflashed.

[tipoti]

Re: LA-D993P No power no charging

source (1-2-3) = 398 kΩ
gate (4) = 416 kΩ
drain (5-6-7-8) = 130kΩ

i tried the bios

[mon2]

Re: LA-D993P No power no charging

Looks ok.

Check the resistance to ground of each coil (inductor).

[tipoti]

Re: LA-D993P No power no charging

I checked the coils, there is no low resistance or short circuit.
When the device was in its last working state, the battery was not plugged in and the non-original charger was connected

The PS_ID line goes in MEC1404. Could the mec 1404 be faulty? Due to fake charger

[mon2]

Re: LA-D993P No power no charging

What is voltage of PS_ID ?

[tipoti]

Re: LA-D993P No power no charging

PS_ID =3.4 Voltage

[tipoti]

Re: LA-D993P No power no charging

I haven't been able to fix the problem yet
There is a working motherboard. does it help fix the other

[mon2]

Re: LA-D993P No power no charging

Yes, it can help.

Does the working unit use the same or different power adapter?