DS1387 IC replacement?

[William R. Walsh]

Hello group!

I have an NCR computer that uses the DS1387 clock and battery backed memory
IC. While this IC is still running and keeping pretty good time, I know it
is only a matter of time before it stops running from a dead battery.

According to Dallas, this part is obsolete/NLA. I tried to see if there were
any successor parts still being made, and although it appears that there
were, these too are out of production.

The part is soldered down on the computer's motherboard. This leads to me to
believe that NCR planned a backup circuit or found a way to power the IC
externally. There is a note on the power supply next to the battery that I
should "see the manual for battery replacement"...so clearly NCR had
something in mind. I can't figure out what that may have been. I have read
the datasheet and I don't see a way to power the chip externally.

I can get someone to unsolder the chip and replace it, but what can I
replace it with? Is there anything compatible enough to work?

The computer is an NCR System 3350, by the way.

William

 

[Roy J. Tellason]

William R. Walsh wrote:

Hello group!
I have an NCR computer that uses the DS1387 clock and battery backed
memory IC. While this IC is still running and keeping pretty good time, I
know it is only a matter of time before it stops running from a dead
battery.

That depends...

The battery is only in use when the computer isn't powered up and running.
I have an old 386 board here that's acting as firewall/router for me (this
is going through it!) and the soldered-in nicad is apparently shot. Which
is unfortunate as the defaults *really* don't work for me. So I just
don't turn that box off, until I get around to tearing it apart and fixing
the silly thing.

Is there no connection on that MB for an external battery apparent?
Usually, though by no means always, these are somewhere near the keyboard
connector. Typically a 4-pin header with one pin missing, though others
have also been used.

 

[Kyle Miller]

"Roy J. Tellason" <rtellason@DONTSPAM MEpa.net> wrote in message news:<uoBjb.296$jg7.245022@newshog.newsread.com>...

William R. Walsh wrote:

Hello group!
I have an NCR computer that uses the DS1387 clock and battery backed
memory IC. While this IC is still running and keeping pretty good time, I
know it is only a matter of time before it stops running from a dead
battery.

The batteries inside these modules can be replaced by a careful
technician. I've done it successfully on a few occasions and it
requires unsoldering the module from the board and prying it open with
a knife. As you cut into it from the top side you will see the battery
right on top. Just resolder the tabs to an ordinary watch battery.
Good luck!

 

[William R. Walsh]

Hi!

That depends...

True. At the moment the system isn't running. It is mid restoration...and
though I will run it at times throughout the process of fixing it up, it
won't be put into continuous use until much later on. I'm thinking it may be
a few years before all the pieces I need come together in sufficient
quantity.

The battery is only in use when the computer isn't powered up and running.
I have an old 386 board here that's acting as firewall/router for me (this
is going through it!) and the soldered-in nicad is apparently shot.

I realize that's true, but I never knew if the Dallas modules switched over
to running from system power when it was available. If that is indeed the
case, I suppose I could just always supply it some nice +5V to keep it
going...

Is there no connection on that MB for an external battery apparent?

If there is, it defies being found...and for the sake of the system I am not
just going to stuff in a battery and hook it up anywhere that "looks right".

The only thing I see is a label stuck to the power supply right by the
Dallas module...it says "See manual for battery replacement." Now, if I had
a manual...I could get somewhere on that...

William

 

[William R. Walsh]

Hi!

The batteries inside these modules can be replaced by a careful
technician. I've done it successfully on a few occasions and it
requires unsoldering the module from the board and prying it open with
a knife. As you cut into it from the top side you will see the battery
right on top. Just resolder the tabs to an ordinary watch battery.
Good luck!

So I have heard. I hacked open a dead 1287 and I'm getting ready to do a
more careful job of hacking open another dead 1287 just so I can become
practiced in this art. Unfortunately, I just don't think I am that good and
I don't know anyone who is and would be willing to dare unsolder the part
from the board.

I don't know why the someone at Dallas wasn't thinking that someday there
would be no direct replacement for these modules and that --worst case--
they should accept external power!

William