CMOS battery change

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J

Jr V

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Jan 22, 2014
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10,510
I recently changed out the cmos battery on a ODIN OEC12C887A (this was quite a proceedure) started the computer and was prompted to press F1 to setup, I set the date and time, auto detec the primary drive, save and exit. The PC boots up and works fine for about 5-10 mins. then it starts to flash off and on with the HD clicking away. I reset the PC and I am promted to press F1 to setup again this time I cannot correct the date or time. I must first shut down the PC disconnect the power and wait for a period of time. Then I can restart and go through the of process of setting up again this time I can set the date and time and start the computer only to have the same thing happen again after a few minuets.
This is an old 386 PC and I do not know very much about PCs.....Has anyone dealt with this type of problem?
 
Solution
navalweaponsofficer
The only thing I can think of it possably a bad power supply. What could be happening is that the PSU can supply good power for a few min and for some reason is failing soon after startup. When the PSU vlotage gets down to 1v it pulls current from the CMOS battery and then the entire system shuts off. When in such a low voltage state it causes the CMOS to clear because it does not have enough power to maintain its memory.

Have you verified that the new CMOS information is actualy saving? to check if it is actually saving you can save your settings and then shut the computer off, then power the computer back on and see if it makes to go into setup. if it makes you go into setup again then your CMOS data is not saving.
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J

Jr V

Honorable
Jan 22, 2014
5
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10,510
Navalweaponsofficer,
The CPU would not bootup CMOS battery low (It was actually dead) That is why I changed the Battery. Found a web site that explained how to do this on the ODIN chip. I replaced it with a new battery CR1220. Checked the voltage prior to install.
 
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navalweaponsofficer

navalweaponsofficer

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Jan 3, 2012
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The only thing I can think of it possably a bad power supply. What could be happening is that the PSU can supply good power for a few min and for some reason is failing soon after startup. When the PSU vlotage gets down to 1v it pulls current from the CMOS battery and then the entire system shuts off. When in such a low voltage state it causes the CMOS to clear because it does not have enough power to maintain its memory.

Have you verified that the new CMOS information is actualy saving? to check if it is actually saving you can save your settings and then shut the computer off, then power the computer back on and see if it makes to go into setup. if it makes you go into setup again then your CMOS data is not saving.
 
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Solution
J

Jr V

Honorable
Jan 22, 2014
5
0
10,510
I started the PC at the prompt key stroke F1 corrected he date and time, auto detect the main drive. Saved and exit, CPU booted fine waited till windows 95 up and running.(I know old op sys) Key stroke shut down, turned off power switch when display prompt said safe to switch off. Waited a min and restarted CPU and prompt indicated that the data was not saved.
I then checked the battery without removing it voltage ok. What now?

Update, I found that when I replace the CMOS battery on the ODIN chip, since it was a sealed chip I had to remove the plastic and resin material and pry up the + contact to access the battery.
I cleaned the contacts and replaced the battery and bent the + contact back in place holding it down with some hot glue.
What I discovered that the contacts while clean and reading good battery voltage, was not a good enough contact to maintain the CMOS settings.
After devising a better way to hold the + contact on to the battery, everything seems to be working fine now.
Feel a little foolish for not making sure the battery had the proper contact even though the voltage reading was good.
Thank you all who responded and for taking the time to advise me, I have learned a lot.
 
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