What might be the cause of my BIOS not retaining settings?

[Minaz]

An annoying problem that I have with my IBM PS ValuePoint SX/25 (6381-F30) PC is that every time the power is turned off or disconnected, the BIOS settings are reset to the factory default. This is very annoying because not only does it reset the clock, but also it changes the FDD to 5.25", and to use the floppy, I have to enter the BIOS to have it auto-reset to 3.5". The Valuepoint BIOS firmware is extremely simple, there is no way to customize most of the settings like you would in a normal bios (e.g. you cannot specify HDD paramenters - it either autodetects the HDD or it doesn't). Also, it means that every time I reboot after turning off the PC, I have to either enter the BIOS to correct the settings, or hit escape to bypass the BIOS check.

Since there are many variations of the motherboard, I am attaching a diagram below. BT1 is the button battery which I assume supplies the BIOS. It's a CR battery and I've replaced it twice with newer batteries off Amazon (Duracell), but this does not solve the problem.

Since it is unlikely that all three batteries all failed, I am wondering what else could be going on that causes the BIOS to not retain its settings? Is there anything I could try get the BIOS to retain its settings again?

 

[Timo W.]

Since it is unlikely that all three batteries all failed, I am wondering what else could be going on that causes the BIOS to not retain its settings?

First, check the battery type of the original. Was it really a CR or maybe a VL? The latter are rechargeables.

Second, don't assume anything about the "new" batteries. Check their voltage to see if they are good. If they don't supply 3.0 volts, they are not.

If all that is sorted out, use a multimeter to check if the traces are good and the voltage from the battery reaches the chips that are powered by the battery. You may find a broken diode or something in between.

 

[Malc]

Second, don't assume anything about the "new" batteries. Check their voltage to see if they are good. If they don't supply 3.0 volts, they are not.

Very good advice, Not so long ago i bought a couple of CR2032 Duracell batteries on ebah intended for a couple of thin clients i have, They had a long "best by date" and i checked the voltages with my DMM which seemed fine, I fitted them and all was well for a few days until i fired them up and found both clients had lost their settings.
I checked the voltages of both the CR2032's and they had dropped to well below 3v, It wasn't until i dug the old packaging out of the bin i realized they were " Made in China " :-( Anyway i bought 2 more from a local shop which cost more and these were " Made in Germany " Problem solved.

 

[Robbbert]

As the others have said, it's 99% certain to be the battery.

But once I had some other fault, the settings were missing at boot, so I entered them, and at the end as you know it reboots with the new settings but they were lost already. Guess the cmos itself was broken. It was an old 486 so I wasn't going to bother further and binned it.

 

[Minaz]

First, check the battery type of the original. Was it really a CR or maybe a VL? The latter are rechargeables.

Second, don't assume anything about the "new" batteries. Check their voltage to see if they are good. If they don't supply 3.0 volts, they are not.

If all that is sorted out, use a multimeter to check if the traces are good and the voltage from the battery reaches the chips that are powered by the battery. You may find a broken diode or something in between.

Hi Timo, thanks for the reply.
Yes, the MB does use CR2032 batteries, there is fortunately a fair amount of literature on this particular MB online still (probably was a popular brand back then), and that is why I was confident I had the right battery at least.

I followed your suggestion about testing the battery, and it tested at 3.2V.

The last step I am a bit hesitant, mainly because I am not electronically technically minded enough to begin to know how to do that. I am sure it will fix the problem, but I have never soldered anything in my life before and wouldn't be able to recognize a diode. I might follow some Youtube tutorial but I will probably end up bricking up PC instead

 

[thenzero]

I don’t know if it’s relevant but I recently had a similar issue. I cleaned the contacts and made sure the springy one at the top was bent down enough to hold the battery well and hit it with a little deoxit (mine was showing a bit of corrosion from a previously leaked battery) and that had me right as rain.

 

[twolazy]

Some battery setups on motherboards use a diode, if the battery is good, and the holder is clean, check that diode if installed.