Bios chip voltages

Thread Starter

Darzo

Joined Nov 5, 2019
2
Hi All first time post.
Would anyone know if the bios chip on a HP laptop has the supply voltage directly from the battery or would it go through a regulator curcuit?.
The chip is a 25Q64FV and has 8 pins. Pin 4 is ground Pin 8 should have 3v but it is sitting at 0v. I cannot load the bios software so the laptop wont boot up. I dont want to replace the chip if it is just a voltage problem.
Could I just connect the battery directly to the chip for a test??
Many thanks
D
 

RPLaJeunesse

Joined Jul 29, 2018
62
NO! That would destroy the chip and a few others. All modern laptops have a PMIC, a power management IC that reduces the battery to all the different voltages needed by the PC. If your problem is truly the BIOS not loading, it could be that the 25Q64FV is power switched and that switch isn't working. If the PC is dead then it's likely the PMIC isn't starting up as it needs to. That could be the PMIC, it could be something else that controls or feeds the PMIC.
 

Thread Starter

Darzo

Joined Nov 5, 2019
2
NO! That would destroy the chip and a few others. All modern laptops have a PMIC, a power management IC that reduces the battery to all the different voltages needed by the PC. If your problem is truly the BIOS not loading, it could be that the 25Q64FV is power switched and that switch isn't working. If the PC is dead then it's likely the PMIC isn't starting up as it needs to. That could be the PMIC, it could be something else that controls or feeds the PMIC.
Hi RP and thank you for replying. Just for clarification, I am referring to the 3v cmos button battery not the main computer battery. The laptop tried to boot, but crashes. Testing the hard drive externally on another computer using the supplier software it passes all the sector checks. When I try to reprogram the bios using the 'windows key +b' the computer goes through all the motions and you can see the files being loaded but at the end it says update failed.

D
 

RPLaJeunesse

Joined Jul 29, 2018
62
Hi RP and thank you for replying. Just for clarification, I am referring to the 3v cmos button battery not the main computer battery. The laptop tried to boot, but crashes. Testing the hard drive externally on another computer using the supplier software it passes all the sector checks. When I try to reprogram the bios using the 'windows key +b' the computer goes through all the motions and you can see the files being loaded but at the end it says update failed.

D
Well, that makes a big difference. There is a good possibility the 3V battery will make the chip come alive. If all else is working this might just get the thing going. Consider using a milliamp meter between the battery and the chip. If you hit say 10 to 20mA there might be a problem that could damage the bios chip and drain the battery. ( I didn't pull the chip datasheet, that should have the typical operating current called out.)
 
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