HP 14-dq0055dx - No Power After Shutdown - Must Reseat Internal Battery First, Then Powers On Normally.

[grimacelord]

Hello again,

I am once again working on this same laptop that I was working on in this thread. I was able to fix all of the problems that it had, but now it has one final problem. The computer will turn on and work completely fine until you shut it down. Once the computer has been shut down, it will not turn on again, nor will it show charging LED until the internal battery is disconnected and then reconnected. Once the battery has been disconnected and reconnected, the computer will then power on and charge normally and everything is fine again until the next shut down where you have to once again disconnect and reconnect the internal battery.

The computer originally had a BIOS/RAM problem (see thread linked to above for more info), so I don't know if it is related to that or not, but I have never dealt with this specific problem before, so I am unsure how to begin troubleshooting. This computer does not have it's own dedicated CMOS battery, only the main internal battery.

I don't know if this is a BIOS issue, a battery issue, or what. This computer was purchased new during Christmas holidays 2023 and rarely used, so it would be quite odd to have the battery be bad/defective in only 5 months and it charges/discharges normally as well as pass HP's Extensive Hardware Diagnostic Tests. In fact, everything passes HP's hardware tests...not really sure where to look...

Computer Information:

Motherboard model number: DA0PAMB46A1 REV: A
Secondary motherboard model number: 0PAB
SKU: 685K4UA
Serial number is: 5CD3223BJP

Repairs That Have Already Been Performed (See other thread)

1. RAM Module replaced
2. Replaced ITE with ITE from identical motherboard
3. Reflashed BIOS with latest available from HP

I am so tired of working on this laptop lol. Can anyone please help me with this last problem so I can get it out here? Thank you so much!

[grimacelord]

My ideas so far is to try and find a comparable schematic since I couldn't find an exact one for this model and study the RTC circuit and look there since the computer will only turn on after being shutdown if the battery is removed and then reinserted, which functions as a CMOS reset. I don't know if I am wasting my time or not, but maybe someone else has some other ideas?

[mon2]

Sounds like a leaky mosfet issue. Review the charger thread by @Piernov.

With no power to the board, meter in resistance mode (not diode mode) -> measure the resistance across the mosfet pins:

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

Review the usual 2 * DCin mosfets for a low resistance measurement. Continue to also check the battery charge (high and low side) as well as the battery enable mosfets in the same manner.

Post all measurements in ohms. A good mosfet will have a high resistance reading. Share the details of the charger IC -> perhaps the 'BQ' series in a QFN package ?

[grimacelord]

Sounds like a leaky mosfet issue. Review the charger thread by @Piernov.

With no power to the board, meter in resistance mode (not diode mode) -> measure the resistance across the mosfet pins:

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

Review the usual 2 * DCin mosfets for a low resistance measurement. Continue to also check the battery charge (high and low side) as well as the battery enable mosfets in the same manner.

Post all measurements in ohms. A good mosfet will have a high resistance reading. Share the details of the charger IC -> perhaps the 'BQ' series in a QFN package ?

Thanks for the reply, mon2!

This board is smaller in size, so they are using components that I am not accustomed to working with. I think I know which mosfets you want me to take measurements of, but could you look at these pictures and just verify which ones you want me to measure so I don't measure the wrong ones and waste your time? Thanks.

Also, the battery charger IC is BQ728

[mon2]

You will certainly not like the new macbooks / ipads and their 0201 or smaller parts that are onboard!! Personally cringe when they come in for service.

The BQ728 is in the witness protection program so not easy to locate datasheets for this device but BQ725 comes up on a valid match. We can study the BQ725 pinout to learn about your logic board.

BQ24725 data sheet, product information and support | TI.com

2-4Cell Li+ Battery SMBus Charge Controller with N-Channel Power MOSFET Selector datasheet (Rev. A) (ti.com)

Locate the mosfets that should be nearby to this charger IC. The mosfets may be on the opposite (or bottom) side of this charger IC. We are after the 2 * DCin N-channel mosfets that will be mating the power adapter to the main power rail and the ACDRV pin # 4 will drive the GATE pin to enable the power path.

When ACDRV is ~25 volts, the gate pins of the 2 * DCin mosfets will enable. Often there is a ~4k ohm resistor between the GATE pin # 4 of the mosfets and pin # 4 of this charger IC.

Remove all power. Meter in resistance mode. One meter probe on pin # 4 of this charger IC. Other meter probe on any mosfet that is nearby -> pin # 4. Stop when you locate the mosfets (there will be 2 of them) with a ~4k ohm resistance.

Once found -> share a close up picture of this region.

[grimacelord]

You will certainly not like the new macbooks / ipads and their 0201 or smaller parts that are onboard!! Personally cringe when they come in for service.

The BQ728 is in the witness protection program so not easy to locate datasheets for this device but BQ725 comes up on a valid match. We can study the BQ725 pinout to learn about your logic board.

BQ24725 data sheet, product information and support | TI.com

2-4Cell Li+ Battery SMBus Charge Controller with N-Channel Power MOSFET Selector datasheet (Rev. A) (ti.com)

Locate the mosfets that should be nearby to this charger IC. The mosfets may be on the opposite (or bottom) side of this charger IC. We are after the 2 * DCin N-channel mosfets that will be mating the power adapter to the main power rail and the ACDRV pin # 4 will drive the GATE pin to enable the power path.

When ACDRV is ~25 volts, the gate pins of the 2 * DCin mosfets will enable. Often there is a ~4k ohm resistor between the GATE pin # 4 of the mosfets and pin # 4 of this charger IC.

Remove all power. Meter in resistance mode. One meter probe on pin # 4 of this charger IC. Other meter probe on any mosfet that is nearby -> pin # 4. Stop when you locate the mosfets (there will be 2 of them) with a ~4k ohm resistance.

Once found -> share a close up picture of this region.

I believe this is the region you are asking for?

[mon2]

Nice and clear pix. Can you take a pic of the other side of the board under this same charger IC. The mosfets we are after are probably on that side. The ones in the posted pix are the battery charge mosfets since there is a linked power inductor.

The reference design from TI offers guidance on is most likely onboard.

[grimacelord]

Nothing underneath the board, just some caps and a few resistors and an IC or two, but here is a pic.