First post, by treeman
Im fixing a 486 board that had barrel battery acid leak. From no response on boot I am now getting 10 beeps which is a cmos error.
I cleaned this board, fixed corrosion, removed alot of components resistors capacitors etc as there was too much corrosion on the vias. I even found a few cracked traces on the back which I fixed now.
Anyway I am stuck on the cmos error, I actually have a identical but working motherboard so I checked all the components around the cmos which is integrated into the opti f82c206q chipset on this board. comparing all resistance readings ground to component pins the readings are same on both boards, no shorts or disconnected pins. The cmos chipset is near the barrel battery so it is definitely related however apart from changing the actual cmos/chipset I am out of guesses. Yes ofcourse I tried resetting the cmos chip, nothing. I checked resistance readings on the cmos chip compared to a working one and its the same, leads me to believe the chip is not internally shorted. So I am thinking some connection between bios and cmos is lost, I have not been able to trace it visually so I fear a multi layer trace might be cracked.
Its a very long shot but anybody ever solve a similar issue?
the motherboard is a chicony ch-486
here is the picture of the cmos/chipset
still some flux and cleaning residue around, but I checked most things here for continuity/shorts