motherboard battery change NVRAM oec12c887a

[heALer]

Hi!
I have a j-656b motherboard with a pentium 133MHz.
It has no CR2032 battery holder on it, it has a NVRAM oec12c887a, with battery and clock circuit inside.
It's solid and directly soldered to the motherboard. The battery inside is dead. I can desolder it and replace the whole thing, but it is
24pin, and desolder that I may mess up the motherboard.
I found on the Internet that the battery inside is connected to Pin 20(+) and Pin 16(-).
Can I solder two wires from those pins to a new CR2032 battery holder? Without taking out the old battery inside?

 

[angel_grig]

Can I solder two wires from those pins to a new CR2032 battery holder? Without taking out the old battery inside?

Yes you can..but pins 20 and 16 on the motherboard are not connected to the battery.They are connected to the battery but only internally.The simplest way to do it,is to melt the plastic with a soldering iron and then solder the cables to the exposed metal contacts.Usually the battery has some power left ,so checking with a multimeter you can confirm that you have found the correct contacts.
Some photos from my soyo pentium I motherboard:
The ODIN chip (thanks God it was on a socket:D)



Checking the internal battery:


The final result:


It is not very easy but it is doable.You can also use a knife like tezza did here:http://www.classic-computers.org.nz/blog/2009-10-10-renovating-a-dallas-battery-chip.htm.

 

[heALer]

Okey, I thought that I could just solder the wires on the backside of the motherboard, on the solderpoints, but if the legs are not connected to the motherboard, than it will not work.
You did a nice job on yours, I will try to do something similar..I just wish that mine was in a socket also.
I was looking at the motherboard today, and I saw and empty place on the motherboard called BT1, looks just like a cr2032 holder should be soldered to that place..I took a picture of it:

 

[angel_grig]

My motherboard also had an empty space for a CR2032 battery but..
a)there are components missing
b)even if you install the battery the current will never arrive to the Odin chip
So,you have to do the hack. Fortunately the wright side of the chip is exposed on your motherboard.Put a piece of paper on the motherboard when working with the soldering iron,to avoid problems with the chip nearby (if for example you drop melted solder by accident).
Good luck!