HP Probook 640 g8 break Fuse / Flashing BIOS with 5V instead auf 3,3 CH341A

[martin86]

Hi,

i had a HP 640 G8 with a DA0X8AMB8E0 Board. I would Flash the BIOS, but i used a CH341A Programmer with 5V instead auf 3,3. Then I thought the BIOS was now defective. I have already replaced it with a new one (flashed the same BIOS).

With the new chip, the notebook has the same error. The charging port lights up once and then goes out again. The notebook does nothing more.

I iced the board with a cooling spray to possibly find a chip that gets hot or has a short circuit. Unfortunately, I didn't find any. I suspect a fuse might have blown. Does anyone have any ideas or is there perhaps a schematic for the board?

Thanks.

[mon2]

Way are the details of your power adapter? It should be a HP brand with 65 watt rating or higher.

Locate where the power enters the board. Then study and share pics of the 8 pin mosfets and charger ic. Often, the fault is in this area. You will require a multimeter to troubleshoot the board.

[martin86]

Hello, thank you for the feedback. I have tested multiple power adapters, each with more than 65W. The behavior is the same when the laptop is operated with the USB-C charging port.

A circuit diagram or anything similar is not available for the board? The MOSFET and charger IC should be near the charging port on the motherboard?

Thanks.

[mon2]

The MOSFET and charger IC should be near the charging port on the motherboard?

Yes. Take a few pics of the area and post them here as attachments. The mosfets are often black in color with 8 pins (4 per side). Usually there are 2 x DCin mosfets that will follow the power adapter connector. These mosfets are enabled using the pin # 4 of the component and are driven by a pin on the charger IC. The charger IC is usually a square chip with pins on each side. HP likes to use charger ICs from Texas Instruments and are marked with a 'BQ' label on the topside. We need to know these details along with the mosfets to move forward.

A very good reading is the sticky above by piernov on charger circuits.

[martin86]

Hi,

here are same Picture auf die Mosfet and Charger IC.

[mon2]

The pics are not very clear to read the top side markings. Search for a square ic with topside markings with ‘BQ’ in the part number. If found, share a pic of that area.

[martin86]

Hi,

i found this 4 chips.

[martin86]

a Chip with BQ Marking is not in the near.

[alexfts20]

martin86 It appears that all the components you're referring to are MOSFETs.
The first one (3P3R0), in particular, seems to be a P-channel MOSFET used in the DC input circuit. To verify its functionality, please follow these steps:

Without power supply/battery connected
Measure the voltage drop between the Drain and Source. Expect about 0.5V.

With power supply connected
Check the voltage at both the Drain and Source relative to GND. It should match the DC input voltage, usually +19V.

P.S. For detailed specifications, you can search online for the datasheet of this MOSFET.

[martin86]

alexfts20 Hi, i check the 3P3R0. This Chip looks like OK, When Power is connected Drain und Source are at +19V like the DC input Voltage.

[martin86]

Hi,

i habe Check the other Mosfet. Here the Picture with Voltage.

[alexfts20]

a Chip with BQ Marking is not in the near.

It must be from the opposite side of the board. It looks like there is no schematic on this board, but you can find the charger datasheet on the TI website.

[martin86]

Hi,

mon2 and alexfts20 I found only one Chip at the opposite of the board that contains BQ Marking. Here are the Picture of the Chip and the Board from the other site. On this side there a no Mosfets.

[mon2]

The first pic with the BQ24780S is the charger IC.

Search this part on the internet to locate a sample datasheet. The logic board will very likely follow the sample schematics.