Latitude 5300 not charging.

[menthol]

Hi guys

Please Help me

I cannot charge my laptop by connecting the AC adapter to it.

[The following is the situation]

The laptop is just connected to the AC adapter without booting.

1. pin 19: ACIN of Charger IC does not go HIGH when connecting the AC adapter with the battery connected to MB. (sheet 44) PR4485 is not mounted.


2. the reason why ACIN does not go HIGH is because pin 5 of PQ4423 is set to HIGH and pin 3 and pin 4 are set to ON.

3. When supplying power from the AC adapter, 0V should be output from the OUTPUT of PU4415, but 4.7V continues to be output.

4. 1V_CPU_CORE is outputting 0V and I think the overvoltage protection is not working.

5. when I connect AC adapter without battery to MB, 0V is output from PU4415 and ACIN goes HIGH. However, even in this case, if I quickly turn on/off the stabilized power supply, it may keep 4.7V. When the regulated power supply is turned OFF, the OUTPUT of PU4415 rises to 1.8V and becomes 0V with decay. This itself is not a problem since this phenomenon is also seen in normal MB. In the MB in question, when the stabilizing power supply is turned on at 1.8V, the output voltage rises to 4.7V, but in the normal MB, it immediately becomes 0V.

[Question]
　What could be the reason why the OUTPUT of PU4415 does not go to 0V with the battery and AC adapter connected to the MB?
Please let me know if there are any other details to check, not limited to PU4415.

[Supplemental]
　The following parts have already been replaced.
　 PU4415, FD4409, PQ4423, PR4450, PR4451

Any advice you can give me, would be greatly appreciated!

Schematic and boardview ---> https://www.badcaps.net/forum/showthread.php?t=101483

[Vesko356]

Re: Latitude 5300 not charging.

Hi guys...

Do not attach laptop schematics and/or BV in this section please!

Schematic Requests ONLY!
https://www.badcaps.net/forum/forumdisplay.php?f=41

Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483

.

[mon2]

Re: Latitude 5300 not charging.

Hello menthol-san.

1) original and recommended power adapter is being used? It is important for the single wire ID check used by the logic board.

2) measure the voltage to ground of PS_ID_R and PS_ID.

Post the voltage measurements.

Dell laptops use the Maxim / Dallas 1-wire communication on the PS_ID line to authenticate the power adapter details.

[menthol]

Re: Latitude 5300 not charging.

Hello mon2-san

Thanks for the reply.

A1: The adapter is a genuine DELL product.

A2: I measured the voltage of PR_ID and PR_ID_R. It seems that the battery is doing something wrong.

　1. Only AC adapter is connected.
　　PS_ID: 3.291 [V]
　　PS_ID_R: 3.287 [V].

　2. Connect AC adapter and battery
　　PS_ID: 0 [V]
　　PS_ID_R: 0.295 [V]

[mon2]

Re: Latitude 5300 not charging.

Remove all power / no battery.

Meter in resistance mode.

Measure the resistance across the mosfet pins to confirm if the mosfet is not defective.

Measure:

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


for the battery mosfet @ PU4412.

Then do the same for PU4413.

Post each measurement. A low resistance reading = mosfet is leaky and is defective.

[menthol]

Re: Latitude 5300 not charging.

Hi mon2-san

Thanks for the reply.

PU4412
source (1-2-3) & drain (5-6-7-8) : 0.562MΩ
source (1-2-3) & gate (4) : 0.602MΩ
gate (4) & drain (5-6-7-8) : 1.002MΩ

PU4413
source (1-2-3) & drain (5-6-7-8) : 5.4kΩ
source (1-2-3) & gate (4) : 52.8kΩ
gate (4) & drain (5-6-7-8) : 95.6kΩ

I think MOSFET seems to be fine.

[mon2]

Re: Latitude 5300 not charging.

PU4413 does not look good. For mosfets, this is low resistance.

Please flux and remove from the logic board -> allow it to cool down and measure the resistance again while it is on your workbench.

If the resistance remains to be low, this part is defective and must be replaced.

reference:
https://electronicsbeliever.com/how-...0good%20MOSFET.

See resistance check method for mosfets.

[menthol]

Re: Latitude 5300 not charging.

Hi mon2-san

Thank you very much.
Very informative and helpful.

When measuring the resistance of a MOSFET, at what resistance level should I suspect it is defective?

Is it necessary to have more than 200-300kΩ between each terminal to determine that it is normal?

[mon2]

Re: Latitude 5300 not charging.

The actual resistance value can vary but should be ok if it is higher range as noted.