The Mother Board

[bobg831]

I have an old biostar MB-8500tuc-a (ver3.2) Motherboard.
it is in a pionex box. my friend gave it to me to look at for her.
after adding ram,(it only HAD 32mg on it), i find it has CMOS problems
NO battery. i dont see a battery spot on the board and i cant find where to jumper a new one in . .
CAN ANYONE HELP ME

thanks
bob

[Aussie]

Right next to the bios chip there's a little black box about an inch or so long and a half inch wide, that contains the battery and realtime clock.

Sometimes these are removeable and replaceable sometimes not, othertimes you can pop the lid off and find a standard coin cell battery inside which is replaceable.

I'm sure that it is possible to supply power to the CMOS by wiring a battery of suitable voltage to the CMOS clear jumper pins but I don't know enough about this to advise you.



Aussie
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[tedybear]

http://www.computerhope.com/help/cmos.htm


Anything there look like the one?

S-

[bobg831]

found a little black box 1.5 '' x .5 ''
says dallas real time clock
it was tied stripped down. looks like it,
have to buy new one
thank you !

[tedybear]

That's the one...Used to have to replace 'em on older CPU boards for work. If you need a hand finding one? Try a search using MCM electronics or ECG parts.

S-

[wiliamjack703]

[evasive]

Nope, he has found he needs to replace the entire RTC/CMOS battery unit. They were made by DALLAS semiconductor.
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We hate rut, but we fear change.



System error, strike any user to continue...

[Karlsweldt]

Those older motherboards with the Dallas RTC design were doomed from the start. Most older motherboards did have two CMOS chips.. one for the "odd" registers, one for the "even" registers (0, 2, 4, 6 etc. are 'even'.. 1, 3, 5, 7 etc. are 'odd'). One of those chips had a battery and crystal as part of the makeup, in a larger case. There was no provision to apply an external power source to the real-time clock. If the Dallas RTC chip was in a socket, easy to replace. But too many motherboards had them soldered in. A bugger to replace! The original chip model was 1287 or 1287A.. the replacement is 12887A, if it can be found.
They are very hard to find today, especially in "new" condition. But there were several ingenious methods to replace the battery and revive the system. But you have to be very careful about doing surgery on the chip, as cutting into the leads for the RTC crystal is possible. Here is one method to revive the Dallas RTC feature.
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