First post, by Ze_ro
So the clock battery on my Pentium 133 machine finally died on me the other day. Strangely, this has left the computer completely unusable! When I boot, it forces me into the CMOS to restore settings, but upon leaving the CMOS setup, the computer immediately reboots and forgets everything I just entered! Great work there, QDI (whoever they were...)
Oh well, I would have replaced the battery regardless, but to my horror when I opened the case, I found that the battery was not in a simple coin holder, nor even soldered to the motherboard... instead it is embedded into the substrate of the clock chip! I looked on the net for some information, and I found instructions on how to grind away the chip casing to expose two of the pins to solder a new coin-cell holder to replace the embedded battery. Has anyone here done this and maybe can provide some insight on the process?
The directions I find all seem to be for a DS1287 (apparently this is a common issue with PS/2 machines), while my clock chip is a DS12B887... near as I can tell, this is designed to be pin-compatible, so the process should be the same, right? I already used a dremel to expose the two pins, and I get a voltage of about 1.12V, so I think I'm good here...
One of the steps is breaking the connection to the existing battery, but is this actually necessary? If I just connect another battery in parallel to the old one, that should be good enough I would think... or would the old battery drain current from the new one? I'd rather not grind down too much more, in case I grind right through the pin I need to solder to.