*CMOS Battery replaced, but!*

I have replaced the CMOS battery in my Risc PC. I have used a triple A re-chargable with a battery holder’ As I was unable to remove the screw holding the Mother Board I had cut the old battery off and used one positive leg and the negative legs to solder the wires for the battery holder. Now I find that, whilst the machine boots it does not remember the time, date, or the number of floppy drives. Have I made a bad connection to the mother board and where should I check with a multi meter to check this out?

Perhaps you omitted to save a CMOS file first.

You should consider reconfiguring these items first.

If they are then not recorded, yes, you’ve screwed up with the mod!

I had cut the old battery off and used one positive leg and the negative legs to solder the wires for the battery holder

Just checking, you did connect the +ve terminal of the triple-A rechargeable to (one of) the two legs from the original battery +ve and the -ve terminal to the one -ve leg? It reads as if you’ve possibly connected the +ve to the single leg and the -ve to the twin legs.

What’s the voltage measured across the battery, and measured across the RTC/CMOS chip (pins 4 & 8)?

Yes I did save the CMOS before taking the battery out and reloaded it afterwards. As I stated all seems fine and booting appear ok except time,date etc.,
I connected the positive wire to one of the two legs of the old battery and the negative to the one leg of the old battery. I connected the positive to the right hand leg when viewing the old battery from the negative side (the side facing into the machine). I will test pins 4 & 8 of the RTC/CMOS chip. The battery was reading 1.2v just before installation.
Is it necessary to remove the motherboard and solder the new wires from the back?

How do I identify the RTC/CMOS chip?

Depends on the board revision. From memory, either right next to the battery, or more or less center of the pcb. It’s an 8 pin package and it has the ticking crystal (slim two pin silver cylinder) right next to it. I’m sure someone will come along with the ic number shortly.

I can see the chip as you have described and there is a voltage of approx 1.2v I am now going to make a bridge between the 2 positive legs, as I have seen in some pictures, I cannot see the harm as the original battery had two positive feeds to the mother board and one negative. Then I will see if this overcomes the problem with the computer not holding time and date info.

If there’s 1.2V across the RTC chip when the computer is turned off then there’s a good connection from the battery to the chip, you don’t need to do anything more there. If it’s still not holding data & time then the fault is not with the battery. Does the time revert back to 12:00 Jan 1st? If so then it’s probably a failed RTC chip. If the time stays at the time you last set it, then it could be a failed crystal.

I have now found out the problem with the date and time not being held. It was a user problem not a computer problem, when I set the time and date I used the Alarm settings not the clock settings. Rather stupid of me, but at least I know that my soldering was not at fault after all. I did find the RTC chip thank you Will Ling and it does give a 1.2v reading across 4 and 8. I have found that it does not matter which positive connection point is used both give the same connection. Perhaps the original battery used to positive legs for physical stability as 3 leg are better than two.
One problem which I still have is with the floppy disc drive, the computer returns an error that the drive it empty, not sure if this fault old or new as have not use it for quite some time. I have ensured the power and data lead are fitted securely into the drive and as the data lead is the same one used by the original ADFS hard drive I cannot see that the connection to the mother board can be at fault. Any thoughts would be appreciated, as I really do not want to dismantle the computer down to the mother board again, too many extras to remove and reassemble just to check the data lead, as the Hard Drive is function correctly!

Have checked everything again all looks ok, but floppy still not functioning, may have to replace it or the ribbon cable.

Today. I Have reversed the ribbon cable, all back to normal. I just seems wrong, but if it works all well and good.