[RESOLVED] CMOS battery failed

Every time I start up this computer I get the messages,
CMOS checksum error - Defaults loaded
CMOS battery failed
Press F1 to continue, DEL to enter setup.

I know that the motherboard battery is on its way out, but how long will it last?
I looked at the mptherboard to see the type of battery but could not see one. The only thing the looks as if it is the battery is a long fat rectangle with the words "Houston Tech HT12888A Real Time 9639A116669V" on it.
Is this the battery? and if so can you still get tham as it is an old machine (Pentium 166).
:confused:

Many of the older motherboards with "non-removeable" batteries like this have a connector on the board for an external battery. Do you have your motherboard booklet or any info on the board ? You need to determine what voltage battery you need and the polarity of the connector.

Just an addition to aigal's post:

Yes, IC You have mentioned, really contains non-removable battery (and CMOS,RTC itself,BTW)inside.

Fisrt of all, check again all jumpers positions. Few times I even had to replace bad (unreliable) jumpers caused that problem.
If all jumpers are O'K - Your RTC IC (Hewston ...)should be replaced (or resoldered, in case if that IC soldered into board).
Aigal is right, that RTC type IC were often used in old 286-586 PCs (especially in brand ones). They are usually reliable enough.
I didn't find yet info about Your RTC IC,though. Personally I've seen a lot of MoBos with Dallas Semiconductor' RTC chips,what, I believe,similar or even same to what You have now,but much more easy to get, I think. You can check out their site here: http://www.dalsemi.com/datasheets/pdfindex.html and may be You'll find analog. May be,though, You'll be more lucky to find exactly same RTC IC as You have failed now.

If you are handy in electronics you can sorder a by pass battery to the old connections and slove your problem.

I'm sorry, but have to disagree.If that chip included only battery, I'd agree. But that chip includes also RTC,CMOS... :(

A used Pentium motherboard I'm just putting into a system now has a Houston HT12888A module on it, socketed. Older boards may have them soldered.

The faulty board which just came out has a Dallas DS12887 which appears to be basically the same so, as Ruslan suggested, a Dallas unit may substitute.

The board with the Houston has a pair of pins adjacent, which I can measure 2.65 volts on, with the PC not powered up. I believe this indicates the internal 3V lithium cell is fitted with a "steering diode". This prevents it from discharging an external battery connected here if the internal cell goes flat. A pair of alkaline AA or AAA cells in a holder (Tandy or similar) will connect up & work fine here, if your board has similar, and if you can measure to confirm the function and polarity.

Again, as Ruslan said, it would definitely not be wise to try to connect up a battery if there is no provision to do so, you could damage the cmos.

The other board has no connector for external battery, the module would have to be replaced. In fact, 200TDI, you can have it if you want to slip over here to Aus & get it!

Can I keep using the machine as it is? or will it give up the ghost some day?


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If we keep on doin' what we always done, we'll keep on gettin' what we always got.

Yes, you'll still be able to use it. You won't be doing any harm, except for that annoying message at startup, and any customized settings in the CMOS that you like to KEEP (eg. Clock settings...) But your not ruining the board, let's put it that way :)

BTW, what part of Ireland are you from? I'm from there too :D

Thank you all for your HELP. It is always a good help.
Going by what you are saying I can continue to use the machine. I was going to install an internet and ethernet cards for games in the home and the internet. Apart for the time not being right and only being able to have the default settings in CMOS everthing will work ofay?

The number of the motherboard is 10/18/96-i430VX-10031996C-00
And I am from Dublin in the South of Ireland or if you want it in more detail 30min drive from Dublin in Salins.

Thank again for all your HELP.
:D

Quote:

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Originally posted by 200TDI:
Apart for the time not being right and only being able to have the default settings in CMOS everthing will work ofay?

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Yes, your system will be fine. In fact if you boot it up and go into CMOS and set everything the way you want, then it will retain those setting until you turn it off again. Why not just leave it on and just turn off the monitor when you don't need it?

So I can install a modem? Do I have to install the modem ever time I switch on the machine?

Quote:

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Originally posted by 200TDI:
So I can install a modem? Do I have to install the modem ever time I switch on the machine?

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As long as the modem doesn't conflict with COM Port 1 or 2 (A or B on some boards) you should be fine without having to go into the BIOS with each boot up to disable COM2.

Many thank to all of you for the very helpful messages.

Problem solved.


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Keep in mind that the true measure of an individual is how thay treat a peson who can do them absolutely no good.

Quote:

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Originally posted by Vice President TBC:
If you are handy in electronics you can sorder a by pass battery to the old connections and slove your problem.

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This is not a good option...the bad battery will short out the good battery.

Also, FYI, we have used these guys for several years:

http://www.battery-biz.com/

Anyway, glad you got the problem resolved.

Later,
DonJ