CMOS Reset (502) The CMOS Checksum is Invalid

[Neto]

CMOS Reset (502) The CMOS Checksum is Invalid

Working on an HP All-in-One. It throws this error every time the system is restarted after having the power cord disconnected.

[Described here https://support.hp.com/us-en/document/c01443485]

I let it do its thing to restore the defaults, but it still does it. So then I read elsewhere to update the BIOS, which I also did – same thing. Didn’t really think it would help, but ran the restore function off of a Windows 10 disk. (That is like the results of SysPrep, where it starts up again with the out-of-the-box experience, going thorough all of the system setup choices, user name, etc.) That didn’t help, either.

Anyone had this experience? All ideas appreciated.

[Neto]

It is a Windows 10 system, so it has that nonsense of automatic location, time & date settings. Could it just be the CMOS battery dead? (I ask because I just remembered that although I had set the time & date already, it was wrong again later. But it's new, so I didn't think about the battery being dead.)

[Wayne in Maine]

The CMOS battery is one of the first things I thought of.

[Neto]

The CMOS battery is one of the first things I thought of.

This does make sense, because it only does it after it has been unplugged. But it's also an All-in-One, which means it is a pain to get inside. (This particular model has no access through the back - you have to remove the screen to get to anything, and it's about 15 screws to remove the screen. Almost as bad as modern laptops.)

[Neto]

I had never corrected the time & date, because I was just starting the configuration process when I saw this. I do not have internet service in my shop, and you have to turn off the automatic time-date process before you can set it manually. I did that this morning, and restarted it after having disconnected the power for around 10 seconds. The time & date were still correct, and the CMOS error still appears. So it is something else, perhaps a bad motherboard. (The problem with a return process is that I have already opened the case, and I am not an authorized HP service provider.)

[ken_sylvania]

I had never corrected the time & date, because I was just starting the configuration process when I saw this. I do not have internet service in my shop, and you have to turn off the automatic time-date process before you can set it manually. I did that this morning, and restarted it after having disconnected the power for around 10 seconds. The time & date were still correct, and the CMOS error still appears. So it is something else, perhaps a bad motherboard. (The problem with a return process is that I have already opened the case, and I am not an authorized HP service provider.)

I have a number of desktops with Intel motherboards that give that error every time they are restarted. I've never worried about it and they seem to run just fine.

[Neto]

Thanks for all of the responses. (I just realized that I put this thread in the Other section, instead of in Tech Talk....)

If this was for me, I wouldn't worry about it, but it's for a customer. (Actually, if it was for me, it wouldn't BE, because I will never again buy a ready-made computer. I've seen too much sloppy short-cuts and inferior parts, not knowing what brand of drives, etc are inside, all that sort of stuff. I'm not singling out HP here, although I've seen things in their systems in the past that do not favorably impress me.)

[Neto]

I have been busy with other projects for the past week, but started a service request with HP, and they suggested something I should try (to attempt to rest the BIOS manually, but it didn't do what they said it should), and so I set it up on the work table & started it up again. That was yesterday late afternoon-evening, but just noticed this morning that while the time & date have not reverted to the manufactured date, which is what I've seen in the past. So to make sure, I set everything again, and then left it disconnected for an hour. It's now showing an hour off. I hadn't noticed this earlier because I was only disconnecting the power for 10 seconds or so at a time.
Is it possible that there is another issue causing this, or would replacing the battery take care of this? (Generally I've only dealt with cases where the battery was so dead that it reverted to the manufacture date of the MB.)

(NOTE: If any Admin sees this, could you move this thread to the tech section, please? I posted it in the wrong place.)

[Neto]

I didn't complete one of the sentences in my last post.

I said:
That was yesterday late afternoon-evening, but just noticed this morning that while the time & date have not reverted to the manufactured date, which is what I've seen in the past.

With the rest of what I had meant to write:
That was yesterday late afternoon-evening, but just noticed this morning that while the time & date have not reverted to the manufactured date, which is what I've seen in the past, the date & time difference amounted to approximately 7 1/2 days back. This matches the last time I had the power cord connected, so the battery is not keeping the system clock running while disconnected from power.

The HP tech told me that the CMOS battery is soldered down, but because my son has a professional soldering kit and often does very fine, close work of this sort, I opened the case to have a look. Turns out that it is NOT soldered down, so I replaced it with a new one. He later tested both batteries, and the one from HP read .13 volts, and the new Duracell one (from our local hardware store) showed 2.83 volts. (From what I found on-line, it should be replaced if it falls below 90%, which would be 2.7.)
But this did not change anything - it is still throwing the CMOS error 502. So I have started a return request, and I guess I'll find out if they are going to honor their warranty or not.