CMOS settings retained only if AC Power Supply is attached. 502 error otherwise. No CMOS battery.

[WryThot]

This laptop generates a 502 error, invalid CMOS settings, upon boot unless the AC Power Supply is attached.  It has no CMOS battery.  The motherboard is the 84A6 made by HP.  An A. I. says the CMOS settings are held in NVRAM powered by the internal battery.  I suspect the NVRAM has been damaged so that it will not hold the settings unless there is a continuous power supply from the power supply system.  The settings are not being held simply powered by the internal battery or the innate ability of NVRAM.  I  can't find a diagram showing where NVRAM chip might be, if it even exists on the board.  Nor do I find a manual for the HP motherboard.   Loading default settings via BIOS does not fix this.  I don't find a software fix that works for this and have concluded it is a hardware problem.  Can anyone confirm I am on the right path thinking it is a problem of the NVRAM?  And if so, just what and how am I supposed to replace that Non-volatile ram?

[Irfan_06]

Hi @WryThot,

Welcome to the HP Support Community.

Thank you for posting your query, I will be glad to assist you.

I see that you are facing an issue with your Laptop that has a CMOS error.

-Perform a power drain on your PC.

1) Unplug the power cord from the PC & wall.

2) Disconnect the power cable from the AC adapter if it is a detachable part and keep it aside.

3) Press and hold the power button down for 15 seconds and release the power button, wait for about 30 seconds.

4) Plug the power cord back into the AC adapter, then connect it to the wall and to the charging port on your PC.

5) Power on the PC and check if it boots into Windows now.

-Update the BIOS for your PC by clicking on the link.

Make sure you keep only the charger plugged in while updating the BIOS for your PC.

Click on the + sign next to BIOS and then download the file.

Open the file and follow the on-screen instructions to complete the update.

-Install all the pending updates for the Windows operating system following the below steps and let me know if that resolves the issue.

Go to Start > Settings > Update & Security > Windows Update and select Check for updates. If the upgrade is available for your device and you want to proceed, download and install it.

- If the issue still persistss, refer to the steps on this link to further troubleshoot and let me know if that resolves the issue.

Please mark this post as “Accepted Solution” if the issue is resolved and if you feel this reply was helpful click “Yes”.

I hope this helps.

Take care and have a great day ahead!

Irwin6

HP Support

[WryThot]

The CMOS settings are not retained even after BIOS has been updated and defaults loaded and saved in BIOS, at least proceduraly.   Although the suggestions offered may work in other cases, hardware issues seem at fault in this instance.  In short, the hardware defects can't be fixed by software means.  And that brings us to how to identify the part of the hardware that has failed.  It can't be a CMOS battery as there is none on this model of laptop.  Can it be failure in whatever holds NVRAM?  Very possibly.  But identification of what that component is and where it is located certainly is not in the HP Service and Maintenance Manual.  Nor can I find a relevant motherboard manual for the HP 84A6 board.  Not a single YouTube nor image makes clearly identifies where the NVRAM might be if it is soldered to the motherboard.  And "if" means that even if I replaced the motherboard, I have no idea if that removes the defect.  It turns out that NVRAM involves more than one chip, which adds to the mystery of repair.  Pursuing a part number for NVRAM is like chasing the wind.  Thank you for the suggestions.  If anyone can suggest how else I might pursue this fix, I would be grateful.  Any graphics explaining the motherboard parts would also be welcome.  Lastly on a secondary issue, am I correct that soldering would be required in replacing the internal keyboard?

[WryThot]

It looks like the 15-da0073wm has no CMOS battery, no RTC battery, no CMOS chip, and no BIOS chip.  The BIOS settings when retained are being retained on the motherboard itself.  The functions of the BIOS chips are integrated therein.  This certainly explains the futility of my search for the identifiers of such chips including the also absent EEProm.  No NVRAM chip is to be had.  As whatever fault exist that prevents retention of CMOS settings yielding the 502 error, such fault is either in the chipset, the CPU, or the motherboard itself.  Lacking the hands on technical skills to repair those components which would likely require soldering even if I narrowed the problem further, my "guess" is that only a 2nd hand motherboard from ebay might suffice to correct the situation.  Just what difficulty would ensue from DIY replacement of the motherboard, is another riddle.  But I think I have narrowed the "problem" sufficently to recognize no chip replacement is going to fix this.  Somewhat ironically, I recognize that even if I replace the motherboard, that would not solve the issue of some of the keys not working on the internal keyboard.  That too has been challenging to figure without basic technical assistance.  Much of what is on the web doesn't even make it clear if you acquire a replacement keyboard, would it include the keyboard connector.  Some say no but some pictures of what you would acquire include the cabling and the connector.  Hopefully, this posting will prevent someone else from falling down this rabbit hole.  I've learned a bit but the definite solution eludes me unless the motherboard replacement proved easy and fulfilling.

[Irfan_06]

Hi @WryThot,

I am sorry to hear that the above steps did not help much but i do appreciate your efforts in performing the troubleshooting steps.

The support on the HP community is currently available within certain constraints. We are striving to enhance our assistance and broaden its scope. We appreciate your understanding and patience.

I've sent you a private message with the instructions. In order to access your private messages, Click the Private message icon on the upper right corner of your HP Community profile Next to your profile Name, you should see a little blue envelope, please click on it or simply click on this link

Take care and have a great day ahead!

Irwin6

HP Support