BIOS 502 Error

[opie1canolli]

Hi Forum Members. I have an HP Envy TE02-0187C with System board 894B Series 10 Blizzard U. About 6 weeks ago I began getting BIOS error 502 boot up warnings. Since then, I have replaced the CMOS battery, reset power and BIOS, updated BIOS and ensured Windows Time services are running. Every time I turn off the computer, it loses time memory and I must go and reset it manually in Windows. When I try to sync the computer, it fails and when I try to change the time in BIOS It acts like it is super hyper and will not let me adjust it easily. Any ideas what might be going on? Thank you.

[Deep_World]

Hi  @opie1canolli,
 
Welcome to the HP Support Community!

Thank you for reaching out, and I appreciate the detailed information you've already provided. I can see that you've performed several advanced troubleshooting steps, including replacing the CMOS battery, resetting the BIOS, updating the BIOS, and verifying Windows Time services. Since the system continues to lose date and time settings after shutdown, let's gather a few additional details and try few checks.

To better understand the situation, could you kindly confirm the below details :

• Does the BIOS date and time reset every time the PC is powered off, or only after being unplugged from the wall outlet?
• Have you noticed any BIOS settings other than the date and time reverting to default values?
• After replacing the CMOS battery, was a brand-new battery installed, and was the battery orientation verified? and also where was the battery replaced from ?

In the meantime, kindly try the below steps mentioned in the link and confirm : 

Additionally  you can refer to this link explaining about the HP PCs - 500, 501, or 502 error displays on a black screen - click here 
 

I hope this helps. 

[opie1canolli]

Hello Deep_World and thank you so much for your reply! For many years I have been using a power hub/surge protector and would hit the master switch (after the computer shut down) to cut power to the computer, monitor and any other USB connected devices. Since this problem has started, I tried leaving the hub on when I powered down the computer. It seems that as long as AC power is applied, the real time clock is working again. I'm not sure what this indicates but I am wondering if perhaps capacitors on the motherboard have lost their ability to maintain a charge when AC power is totally disconnected, or perhaps, after many years, the surge protector has gone bad. Any ideas? Thank you!

[Kuroi_Kenshi · Accepted solution]

Hi @opie1canolli,

Welcome back!

Thank you for the additional information. The fact that the date and time remain correct while AC power is connected but reset after the computer is completely disconnected from AC power is an important clue.

Since you have already replaced the CMOS battery, reset the BIOS, and updated the BIOS, I would not recommend repeating those steps.

Please try one additional check:

• Shut down the PC normally.
• Leave the surge protector/power hub turned on so the PC remains connected to AC power.
• Leave the PC powered off for several minutes, then turn it back on.
• Check whether the BIOS date and time are retained.
• Then repeat the test after completely disconnecting AC power.

If the time is retained with AC power connected but is lost whenever AC power is removed, this would indicate that the system is not retaining the RTC settings when external power is unavailable.

I would not assume that the surge protector or motherboard capacitors are the cause based on this test alone. Since the CMOS battery has already been replaced, if the behavior consistently occurs only after AC power is removed, the next step may require further hardware-level diagnosis.

Please let me know the result of the above test, particularly whether all other BIOS settings are also reset or only the date/time.

Best regards,
Kuroi_Kenshi