Asus TUF Gaming F16 (2024) FX607J no power no ACDRV

[zaurus81]

0.9 Ohm (resistance between red probe and black probe 0.4 Ohm )

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance between pins # 1 and #2 on the charger IC. What is the resistance in ohms (with the current sense resistor onboard)? Measure directly on the charger IC contacts.

[zaurus81]

With sensing resistor in place and diode removed i've 4.3 volt unstable (up and down from 3.9v to 4.7v with multimiter) on main power line. So diode has nothing to do with it.

[zaurus81]

I have the same database (paid) for schematics as you, search GA401QM page 92
I try to start the board with the bench power supply, without the diode

[mon2]

That is a great find! Was hunting for the same but could not find it. Which schematic are your referencing with this partial screen grab? It can help us debug your case.

Leave this diode off the board. Without this part - is the board able to operate normally?

PS: The lack of using the originally beefy adapter is of concern. Purchase / borrow a suitable adapter. Maybe available through Amazon?

[zaurus81]

Smd Marking code is A7t. I found this diode in another asus schematic. see photos

[mon2]

Post a clear pic of D6001. Wish to confirm the smd markings to confirm against the diode datasheet.

Continue to trace each pin of the mystery rail. This would have been helpful earlier.

[zaurus81]

20 volts coming from the power jack (PVADPTR line) goes to the diode D6001 passing through the resistor R6016 (13.7K). This is a switching diode (datasheet) and this is where the 4.3 volts are generated. By removing the diode I no longer have 4.3 volts in the sensing resistor. I tested the diode out of circuit and it seems ok. Unfortunately I don't know what function this diode performs and if it is doing its job. See boardview

[zaurus81]

Here I am. New bq just installed. Nothing changed. I still have 4.3 volts on the main power line with the sensor resistor removed from the board

[zaurus81]

Some of the asus gaming boards wont work with bench PSU and there will be no 25V at ACDRV. When original adapter is used,ACDRV works fine at 25V. faced multiple times. So before experimenting,use a original charger first.

This is something I thought of right away. Unfortunately I don't have the original charger, which is a 20V 12A charger. My bench power supply gets to 5A. However when I disconnect the sensing resistor I get 25v on ACDRV.

[mcplslg123]

Some of the asus gaming boards wont work with bench PSU and there will be no 25V at ACDRV. When original adapter is used,ACDRV works fine at 25V. faced multiple times. So before experimenting,use a original charger first.

[zaurus81]

Ok, thanks for your time. I just ordered the charger ic, it will arrive in 4 days. As soon as I mount it I will update the thread

[mon2]

This dual diode appears to be ok. Replace the charger IC and do update this thread.

[zaurus81]

In photo you read voltages values to grounds of each pin of this dual diode.
In diode mode i read 0.289 voltage drop for each diode (red probe to anode and black probe to cathode). Reverse it give me 0.L.

If you need i post boardview on appropiate section

[mon2]

Disconnect the battery (if it is connected). Connect the external power adapter. Measure the voltage to ground on each pin of the commonly used dual diode on the Vcc pin 28 of this IC. This is a dual common cathode diode with one leg feeding the power adapter voltage; other leg feeding the battery voltage to power this BQ charger IC.

Confirming if this dual diode is leaking and causing this mystery voltage to appear onto the ACN pin. Test all 3 pins on this dual diode.

[zaurus81]

Voltage to ground of 1st DCin mosfet are:

Gate 25V (i have resoldered 4.2K resistor in series on ACDRV line)
Drain 20V
Source 20V

Here the values of 2nd Dcin mosfet out of the board:

source (1-2-3) & drain (5-6-7-8) ----> 0L (with inverted probes 3.6Mohm, i don't know why)
source (1-2-3) & gate (4) --------------> 0L
gate (4) & drain (5-6-7-8) --------------> 0L

I also checked the mosfet in diode mode. I read the voltage drop of the diode integrated in the mosfet from source to drain (red probe on the source and black on the drain, N-channel). Also when I apply the red probe to the gate and the black to the source I get conduction between drain and source (0.002). This indicates that it is working.

With the 2nd dc in mosfet removed, i see same values (see photo).
Looks like I need to buy a new bq24800.

[mon2]

Remove the 2nd DCin mosfet off the board. After you do this, measure the voltage to ground on each pin on the remaining 1st DCin mosfet.

When the 2nd Dcin mosfet is removed, allow it to cool down on your work table. Then, meter in resistance mode.

Measure the removed mosfet as follows:

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

Post each measurement. With the 2nd dc in mosfet removed, do you still see a voltage on ACP or ACN? If yes, for sure the charger IC is defective and must be replaced. Suspecting the power path for this leakage is through the Vcc pin on the BQ charger IC.

[zaurus81]

See photo for results. 4.3V and 0.3V
thx for your patience

[mon2]

Flux and remove the 4k resistor that will be in series with the ACDRV pin. Do not lose this tiny resistor.

Power up. Now the DCin mosfets are supposed to be OFF. What do you measure now on the ACP and ACN pins?

[zaurus81]

the battery has always been disconnected. One thing I forgot to mention is that I have no current draw from the bench power source.