I would recommend learning to desolder on some old non-working (or disposable) board, then desoldering the Dallas chip and soldering a socket. The other option to another DS12887 is one of these replacements - https://www.tindie.com/products/glitchwrks/gw … acement-module/ which won't need a socket.

Thanks very much for the reply.

I do have a few non-working boards lying around that I can practice on.

I wasn't aware of the option of soldering a socket or that neat-looking device you linked to, and both are appealing. I assume that soldering a socket makes the Dallas units pluggable.

If you are aware of any good beginner resources for a job like this I would appreciate it if you could pass them my way. I have seen a few good videos on soldering in general, but I haven't found many on this specific job where the pins go through the back.

Thanks again.

Yes, with a socket no more soldering is needed in order to insert or remove the chip.

I can't recommend any guides to soldering, as I learned as a child 50 years ago, but I would be surprised if there are none on YouTube. My preference when desoldering is to use a solder sucker when I have melted the solder, but I know some people like to use braid - again, I have no experience with braid, so can't advise on that. That something else I assume you can find on YouTube. Hopefully someone with more up to date experience can help more with finding guides.

you should watch louis rossmann. Though I'm not sure which of his videos you should watch.

I'm vaguely familiar with him but didn't think to look him up for some reason, so thanks.

Oh and debs (or anyone), I was just wondering if you have a preference between soldering a socket and that replacement module you linked to in the post above? I guess I like the socket because it feels more 'original' and therefore safer for some reason, but the replacement module looks convenient.

I'm planning to use the module I linked to on systems that have Dallas chips, but it is more expensive and not original, which matters to many collectors, so even with that I might use a socket.

Ok well I think I prefer the module too but I've got a bit of homework to do. Thanks very much once again!!

I agree with th previous posters, but it is also possible to fix a dead Dallas module.
I did it myself once, because I was too afraid to desolder the module in my 286 (which was located on the motherboard's edge).

Essentially, someone has to carefully use a file, a soldering iron, a drill (maybe).
Then, the old battery has to be disconnected on either plus or minus side.
An external battery is then used as a replacement.
https://www.classic-computers.org.nz/blog/200 … attery-chip.htm

Of course, most people here would likely argue that a repair isn't worth it and that you should just buy one of these new Dallas modules.
Well, they aren't wrong. It really depends on your skills. For me, desoldering was harder due the missing tools (heat gun),
so I went the tedious route of "opening" the Dallas module with a file and a soldering iron.

Edit: If you want to save yourself from frustration, make sure you have access to proper tools first before starting.
Or to quote a friend "I'm too poor for bad tools" . 😉

Pardon my ignorance, but is a heat gun necessary? I assumed you only needed the soldering iron (+ flux and desoldering wire). I did see one video of someone removing the dallas chip and I believe they used some kind of hot air device with a fancy bit on the end to target the two rows of pins. Is there any risk of burning things other than solder using a regular heat gun?

I also realize that this is now off-topic. I might start a thread in the hardware forum later.

If the computer boots then you don't need a working cmos battery. It just gets real old real quick having to go into setup every time to setup everything every time you turn on the PC.

If you can get into the setup menu it should either detect the hard drive or allow you to configure its settings. This would need doing before formatting the HDD even with a working battery.
If its still got an old copy of Win95 or whatever installed that should be enough to pull any data you want off the hard drive or at least check if anything is worth saving.

You'll notice alot of if's above, that's because machines that use Dallas chips can be real funny about not having a working battery but to me just sounds like you need to configure the floppy drive and hard drive and you'll at lest be able to get in and poke around the contents.

Sorry, I think my first post was worded a bit weirdly. I was able to get the data off by pulling the hard drive out and mounting it to my current pc. The system will boot with the failing hard drive. What I want to do is install a fresh copy of Windows 98 SE on a new hard drive. The problem is that I don't think I can do this without a working CMOS: I need to install from CD-ROM (my Win95 boot floppy doesn't appear to work), which is not possible with the default BIOS settings. I have to set it to boot from CD-ROM, but when it reboots the setting is gone. I suppose if there was a way to change the setting and continue booting (without rebooting) I would be ok, but as far as I know that isn't an option.

Sorry for the confusion.

winrick wrote on 2021-01-04, 15:16:

Pardon my ignorance, but is a heat gun necessary? I assumed you only needed the soldering iron (+ flux and desoldering wire). I did see one video of someone removing the dallas chip and I believe they used some kind of hot air device with a fancy bit on the end to target the two rows of pins. Is there any risk of burning things other than solder using a regular heat gun?

I also realize that this is now off-topic. I might start a thread in the hardware forum later.

No, It's not necessary if the motherboard was made by normal, non sadistic engineers. 😉
Actually, using a soldering iron and some desoldering braid is much safer for yourself.
A hot gun needs very cautions usage and some practice. It can tear of the markings and the wood of a pencil within a second.

However, sometimes the holes are so small and the PCB traces so thin, that it is very tricky to lift an IC without breaking the traces/rings around the holes.
With only a soldering station and some manual solder sucker this can be very frustrating.
A true desoldering station with an automatic sucking mechanism (pump) makes this much easier, I guess.

That's why I decided for myself (in this case) to leave the clock module installed and hack it.

Edit: I didn't mean to add some additional confusion to the matter.
I rather meant to show some alternatives. 🙂
Depending on your motherboard, desoldering can work fine.
I think watching some YT videos may help. Then you can decide yourself what works best for you and your motherboard.

No problem. I want to consider all reasonable options so I appreciate you bringing all this up. All of this is really helpful for a newb like me.

The mobo in question is made by ASUS so hopefully the holes are reasonable? Although I suppose a good manufacturer can do weird things too. I have a half-fried motherboard lying around that I think I will practice on to see how easy/hard I find it. I'm about to spend about $100 on equipment and other items for something I may use once and never again, but it's something I've always wanted to try.

winrick wrote on 2021-01-04, 17:59:

Sorry, I think my first post was worded a bit weirdly. I was able to get the data off by pulling the hard drive out and mounting it to my current pc. The system will boot with the failing hard drive. What I want to do is install a fresh copy of Windows 98 SE on a new hard drive. The problem is that I don't think I can do this without a working CMOS: I need to install from CD-ROM (my Win95 boot floppy doesn't appear to work), which is not possible with the default BIOS settings. I have to set it to boot from CD-ROM, but when it reboots the setting is gone. I suppose if there was a way to change the setting and continue booting (without rebooting) I would be ok, but as far as I know that isn't an option.

Sorry for the confusion.

Ah all good then!
Good luck with the Dallas chip replacement, I'm in the same boat as you. The one in my very first PC died last year. 25 years it's lasted so I cant complain but due to lack of time, tool's and skill that'll have to be a project for a few years down the track when I at least get 2 out of 3 of those things.
But its worth it. I've got 3 486's and technically that was the least interesting but it had the most sentimental value so was the one I always used first 😀

Thanks, same to you! I've got a 486 here as well which miraculously seems to be in pretty good shape. I'm largely motivated by sentiment as well. Love the look and feel of old software. I'm a Linux guy nowadays and I think this is a big reason why. Anyway cheers!