ASUS TUF Dash Motherboard FX516 REV 6.0 Model Device Not Charging

[lazenes]

The device is not charging with the 19V 180W DC charger. If the battery is full, the laptop powers on normally. I can charge it via USB Type-C, but it’s very slow. I checked the schematics but couldn’t find a solution. I even replaced the BQ24800 battery charging IC, but the issue remains the same. I suspect a MOSFET or a fuse that I might be overlooking is preventing it from charging with the adapter. Has anyone experienced a similar fault before or has any advice?

[mon2]

Attach the power adapter. Measure the voltage to ground of:

ACDET
REGN
ACDRV

[lazenes]

Attach the power adapter. Measure the voltage to ground of:

ACDET
REGN
ACDRV

Thanks for your reply. Could you please let me know which voltages or signals I should measure and at which test points or pins? That would help me narrow down the problem. (For example, ACDET = 14v)

[mon2]

See attached. Proceed only if your meter leads are fine tipped. Otherwise, the short circuit of the pins can be lethal to the board.

Black meter lead to ground. Red (fine tipped) lead to pin to test. Meter in 30V dc scale or higher.

If all is well, ACDRV should be ~25v. REGN should be ~6v. ACDET must be 2v4 or higher else the DCin mosfets will remain disabled.

[lazenes]

See attached. Proceed only if your meter leads are fine tipped. Otherwise, the short circuit of the pins can be lethal to the board.

Black meter lead to ground. Red (fine tipped) lead to pin to test. Meter in 30V dc scale or higher.

If all is well, ACDRV should be ~25v. REGN should be ~6v. ACDET must be 2v4 or higher else the DCin mosfets will remain disabled.

I checked the voltages as you suggested. ACDRV is around 25V, REGN is about 6V, and ACDET is above 2.4V, so the readings look fine. However, the battery still does not charge with the DC adapter. Do you have any idea what else I should check?

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance directly on pins 19 & 20 on the charger ic. One meter probe on pin # 19. Other meter probe on pin # 20. What is the resistance in ohms?

[lazenes]

Remove all power. Meter in resistance mode. Measure the resistance directly on pins 19 & 20 on the charger ic. One meter probe on pin # 19. Other meter probe on pin # 20. What is the resistance in ohms?

I removed all power and measured directly on pins 19 and 20 of the charger IC with my UNI-T UT33D+ multimeter set to the 200Ω range. The reading was about 20.8 ohms.

[mon2]

This leg of the circuit is OK (comparing against the schematics of v4.0) = ~20 ohms.

Remove the pre-charged battery. Attach only the power adapter. Does the logic board power up normally? If not, measure the voltage to ground of the DCin mosfets.

Measure the voltage to ground of:

PQ8901 (1st mosfet)

source (1-2-3)
gate (4) ; should be ~25v
drain (5-6-7-8)


PQ8902 (2nd mosfet)

source (1-2-3)
gate (4) ; should be ~25v
drain (5-6-7-8)

[mon2]

Measure the voltage to ground of the following with the power adapter and battery:

MB_MAX_POWER ; this voltage is critical and defines what the logic board is detecting as the power rating of your external power adapter

If this voltage is not correct, the battery will not charge.

[lazenes]

This leg of the circuit is OK (comparing against the schematics of v4.0) = ~20 ohms.

Remove the pre-charged battery. Attach only the power adapter. Does the logic board power up normally? If not, measure the voltage to ground of the DCin mosfets.

Measure the voltage to ground of:

PQ8901 (1st mosfet)

source (1-2-3)
gate (4) ; should be ~25v
drain (5-6-7-8)


PQ8902 (2nd mosfet)

source (1-2-3)
gate (4) ; should be ~25v
drain (5-6-7-8)

I have taken the voltage measurements you requested on PQ8901 and PQ8902. I marked all the readings directly on the schematic/image and attached it here for your review

[lazenes]

[QUOTE=mon2;n3729133]Measure the voltage to ground of the following with the power adapter and battery:

MB_MAX_POWER ; this voltage is critical and defines what the logic board is detecting as the power rating of your external power adapter

If this voltage is not correct, the battery will not charge.

I couldn't read the value at MB_MAX_POWER. In my schematic, under the IO integrated circuit, this point.

[mon2]

Confirm the presence of a RTC battery. Measure the voltage to ground of this battery which should be ~3v.

(from another board schematic but should be similar to yours)

[lazenes]

Confirm the presence of a RTC battery. Measure the voltage to ground of this battery which should be ~3v.

(from another board schematic but should be similar to yours)

In my board, the battery is integrated (not removable) and the related +3V circuit components shown in the schematic are missing. The battery circuit area is also empty, so it seems incomplete compared to the diagram.

[mon2]

Ok. Confirm if you have ~3v on the other side of resistor R8935. This voltage is required to have a non-zero voltage @ MB_MAX_POWER.

[lazenes]

Ok. Confirm if you have ~3v on the other side of resistor R8935. This voltage is required to have a non-zero voltage @ MB_MAX_POWER.

I checked resistor R8935, but there is no 3V on either side of it.

[mon2]

Does the board power up ok without the battery but using only the power adapter? The adapter power rating is not being sensed properly due to the above circuit. This is required to inform the logic board that the adapter is capable of powering the board AND charge the battery pack.

[lazenes]

Does the board power up ok without the battery but using only the power adapter? The adapter power rating is not being sensed properly due to the above circuit. This is required to inform the logic board that the adapter is capable of powering the board AND charge the battery pack.

Without the battery, the board does not power on with only the adapter. With the battery installed, it powers on but still does not charge. In this case, what can be done to repair/restore the MB_MAX_POWER circuit so that the adapter power rating can be detected correctly?

[mon2]

Can you share the boardview diagram for your board? It is not in my database. Or link in the schematic sub-forum. Is the boardview diagram matching your board exactly?

[lazenes]

Can you share the boardview diagram for your board? It is not in my database. Or link in the schematic sub-forum. Is the boardview diagram matching your board exactly?

The schematic I have is for rev 4.0, while my actual board is rev 6.0. The diagram matches about 85% of the board, but there are some differences.

[mon2]

Locate and measure the voltage to ground on each leg of SL3006.