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Finding a Dallas DS1287 replacement
- Thread starter Tiberian Fiend
- Start date
DOS lives on!!
Veteran Member
Once you replace the battery, you'll need to run the reference/SETUP disk to your specific model.
If you haven't got a reference disk, you can get the images at
http://www.walshcomptech.com/selectpccbbs/
If you haven't got a reference disk, you can get the images at
http://www.walshcomptech.com/selectpccbbs/
k2x4b524[
Veteran Member
where were you able to procure a sample of one of those?
Tiberian Fiend
Veteran Member
sergey
Veteran Member
Mouser sells both DS12887 modules and DS12885 ICs (the same IC as used inside DS12887, but without battery and crystal). They are not very cheap though. I bet there are many other places where you can buy them, but I like Mouser because they sell new components (other places might sell you modules made 10 years ago, with almost completely discharged batteries).
Last week I repaired two DS1287 modules in my Intel Professional Workstation boxes, and soldered / glued nice CR2032 battery holders on top of them. The process is really very simple. If needed I can post some pictures.
BTW Intel Professional Workstation is a really interesting box. Kind of 1990's Intel vision of PC of the future. It is 486 based, EISA bus, low profile (7.6 cm / 3" high) box, with on-board SCSI, Ethernet, VGA (all this in '91 or so). The box could be opened by unscrewing only one single screw, there is no wires inside the box except short IDE and HDD power cables (5 cm / 2" long or so). If people are interested, I can start another thread with system description...
Last week I repaired two DS1287 modules in my Intel Professional Workstation boxes, and soldered / glued nice CR2032 battery holders on top of them. The process is really very simple. If needed I can post some pictures.
BTW Intel Professional Workstation is a really interesting box. Kind of 1990's Intel vision of PC of the future. It is 486 based, EISA bus, low profile (7.6 cm / 3" high) box, with on-board SCSI, Ethernet, VGA (all this in '91 or so). The box could be opened by unscrewing only one single screw, there is no wires inside the box except short IDE and HDD power cables (5 cm / 2" long or so). If people are interested, I can start another thread with system description...
DOS lives on!!
Veteran Member
Was your battery in a socket or soldered to the motherboard? And how easy (or difficult) was it to find both of the pins? Some pictures would be good for a future reference.
I'd be interested to see what that Intel system looks like on the inside.
I'd be interested to see what that Intel system looks like on the inside.
sergey
Veteran Member
DS1287 modules were installed in sockets and I extracted them before patching. It is possible to patch soldered modules (people have done that), but it could be more difficult, depending on module placement, other components nearby, etc.
The patch work is fairly easy, no problem with locating pins. All you need is a sharp knife, soldering iron, CR2032 battery holder (sold in Radio Shack for example - http://www.radioshack.com/product/index.jsp?productId=3060977) and battery, some wires and glue (glue gun).
I'll take and post some pictures of my DS1287 patch work and PWS tonight...
DOS lives on!!
Veteran Member
Yep, that's one method of doing it. I usually perform the 2x AA batteries method, but both do the same job.
Not all DS1287s are socketed. There are those, like in early Compaq laptops (SLT-286 and 386) that are soldered into the motherboard. I've had to do that rework with my SLT.
Not all DS1287s are socketed. There are those, like in early Compaq laptops (SLT-286 and 386) that are soldered into the motherboard. I've had to do that rework with my SLT.
Chromedome45
Veteran Member
Maybe a day late and a dollar short but Jameco still has them as well as the 12887. Here: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_76646_-1
DOS lives on!!
Veteran Member
Look at post #4.:D
SiriusHardware
Veteran Member
If you want the reassurance of buying from someone really mainstream, RS also have the DS12887, the datasheet for which includes a statement to the effect that it is designed as a direct replacement for the DS1287.
http://uk.rs-online.com/web/p/real-time-clocks/0133781
However, looking over at related threads in the Vintage Computer Forum there are some people saying that the DS12887 is not always usable as a direct replacement for the DS1287, although they don't take the trouble to explain why. RS's price for the DS12887 seems fairly reasonable: Probably worth a try?
http://uk.rs-online.com/web/p/real-time-clocks/0133781
However, looking over at related threads in the Vintage Computer Forum there are some people saying that the DS12887 is not always usable as a direct replacement for the DS1287, although they don't take the trouble to explain why. RS's price for the DS12887 seems fairly reasonable: Probably worth a try?
gslick
Veteran Member
It might be the case that the DS12887 is less forgiving of some systems using internal bits that are documented as reserved than the DS1287 was and that can cause problems. I don't have any links handy at the moment to back that up.
Chuck(G)
25k Member
The "why" of the 12887 not working in place of the 1287 may be hard to qualify for most. "Doesn't pass POST" might be as good as it gets.
But yes, there are those who have shelled out for the 12887 and met with failure.
But yes, there are those who have shelled out for the 12887 and met with failure.
I personally can confirm that the 12887 does NOT work as a replacement for the 1287 in the Dell 316SX machine. It looks like it works, but it fails to actually save the CMOS settings over power cycles.
Chuck(G)
25k Member
Which is the lesson every EE eventually learns--that datasheets are useful, but one is advised not to take them at face value.
I wonder if it is due to BIOS bugs or something similar.
BTW, on DS1387/1587 etc. I wonder if DS17287/17487/17887 might be worth trying (from the datasheet they do look similar):
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS17887.html
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS17887.html
Zippy Zapp
Experienced Member
After reading the data sheets for the 1287/12887/1285/12885, really the only difference between the 12885 and 12887 is the xxx87 comes with the battery and crystal encapsulated where as the xxx85 has pins for crystal input and 3v battery source. Couldn't a little circuit board be made to hold a DS12885 chip with a crystal and a CR2032 coin cell holder with pins to plug in to the original socket?
Just a thought.
Just a thought.
Not sure you'd even need a circuit board. Just bend the crystal pins up and solder it directly onto them and do the same with the 3V battery pins. Could eve just put on a 2 pin header and then it could be used with any 3v source.