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Dallas Clock Chip Mod

S

Smack2k

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Is it possible or advisable to modify a Dallas Clock Chip with a coin cell battery holder while the chip is still in the motherboard? Or too dangerous?
 
I've done it and seen others do it to the Onyx IO4 board among others where there is too big a risk damaging something trying to desolder it. The key is to just work very carefully with the dremel.
 
I shall try it out and see how it goes!!! I am pretty good with a dremel (much better than soldering that chip out and then back in!)
 
I've done it on a board once; I damaged the board beside the module and it was unusable thereafter. If I had been using better tools and been more careful it would have worked. You "can" do it but you need to be precise in your actions.

Some boards, the module is directly adjacent to an expansion slot and the battery contact side might be inaccessible. It's a no-go there.

I have also desoldered the RTC module and put the new one (or modded one) into a DIP socket instead...that's the approach I would personally recommend. You need a decently hot iron to melt some of the contacts' solder all the way through and a good desoldering tool of your choice. I prefer the vacuum sucker things but others have differing opinions.

Worth noting, the same can also be done to the ODIN-brand compatible modules, and Houston Tech modules (but they're a little different and easier, the lid just pops off, it isn't all glued together in potting compound).
 
I've recently done it to a Pentium socket 4 mainboard, Intel Premiere I think... it had the DS1287 on board and soldered in. Just used my Dremel like thingie and went very careful, job was done in about 20 minutes, though:

DS1287_01.jpg
DS1287_02.jpg
DS1287_03.jpg
 
Grandcheapskate said:
Would this Dallas chip also hold the CMOS? If so, wouldn't you have to do the battery hack described in this thread?

http://www.vcfed.org/forum/showthread.php?49058-CMOS-settings-will-not-save&highlight=
Click to expand...

Yes, The CMOS is held in the Dallas Clock, or at least has the settings saved....the process I need to do is exactly like the one Denniske1976 posted

kishy said:
I've done it on a board once; I damaged the board beside the module and it was unusable thereafter. If I had been using better tools and been more careful it would have worked. You "can" do it but you need to be precise in your actions.

Some boards, the module is directly adjacent to an expansion slot and the battery contact side might be inaccessible. It's a no-go there.

I have also desoldered the RTC module and put the new one (or modded one) into a DIP socket instead...that's the approach I would personally recommend. You need a decently hot iron to melt some of the contacts' solder all the way through and a good desoldering tool of your choice. I prefer the vacuum sucker things but others have differing opinions.

Worth noting, the same can also be done to the ODIN-brand compatible modules, and Houston Tech modules (but they're a little different and easier, the lid just pops off, it isn't all glued together in potting compound).
Click to expand...

I thought about doing that with the socket, but I am MUCH better with a dremmel than I am a soldering iron. Those pins are close together on the board and I fear when I attempt to solder the socket holder on, I will either create cold joints or cross some of the pins with solder going between each....

The chip on this board is away from the slots and has easy access to it in terms of space for the dremmel, so I am gonna give that a go.

Anyone ever used an old soldering iron to burn the plastic away on those Dallas chips? I did it for a RTC on a Sun Sparcstation and easily got down to the pins and then from there dremmel'd out the last few areas. But that chip was out of the board when I did it....not sure what kind of damage I could do with this chip still in the board...
 
Hmm, I would have thought that the "plastic" was epoxy-resin-based potting compound. A slip of the iron could mean disaster. But maybe you've got better hand-eye coordination...
 
Lol.....I just call it plastic. You are right, it is some compound, but I had good luck with an old soldering iron as it messes up the tip....but it gets through the stuff pretty quick. I do have Decent hand eye still, even though it's getting worse as I get a little older!! 3 weeks away from 40, not as good as it was, but still pretty decent!!!
 
I am gonna start tonight and begin scraping with a knife. If I don't find myself getting there, I am gonna bite the bullet and desolder it and then do it right

Tezza, but fan of your blog. I really enjoy reading it. It's something I've wanted to do as I go through various retro computers and projects but just can't get myself started on it (blogging)
 
Smack2k said:
Tezza, but fan of your blog. I really enjoy reading it. It's something I've wanted to do as I go through various retro computers and projects but just can't get myself started on it (blogging)
Click to expand...

Thanks. I find my blog articles are often useful to myself, as I sometimes forget why and how I've done something in the past :)

I like writing them up. For me, it draws an underline under a project and finishes it off. In essence they say "Here's what I did, here's the result and here's what I learnt". It's good to know others enjoy them and gives me motivation to keep documenting these activities.

Tez
 
Keep up the good work, I for sure will keep reading...

So I desoldered the chip from the board....no issues.....I have cut into it and hit what seems like metal, but its all one solid mass on both sides of the 3 middle pins...I dont see the metal piece that goes up to a smaller neck (that gets cut) and then up to the rest of the metal. Its all one seemingly metal piece....this is a DS12887 Chip if that helps....
 
Smack2k said:
So I desoldered the chip from the board....no issues.....I have cut into it and hit what seems like metal, but its all one solid mass on both sides of the 3 middle pins...I dont see the metal piece that goes up to a smaller neck (that gets cut) and then up to the rest of the metal. Its all one seemingly metal piece....this is a DS12887 Chip if that helps....
Click to expand...

Hmm...I can't say if it's the same as the DS 1287 ones' I've done or not. It might be different. I'm assuming you've got the original source instructions, like I had.

Tez
 
Crap like this made me upgrade my DOS machine to a Socket 7 board with a proper cr2032 for the CMOS... not going to mess with RTCs anymore.
 
Smack2k said:
Keep up the good work, I for sure will keep reading...

So I desoldered the chip from the board....no issues.....I have cut into it and hit what seems like metal, but its all one solid mass on both sides of the 3 middle pins...I dont see the metal piece that goes up to a smaller neck (that gets cut) and then up to the rest of the metal. Its all one seemingly metal piece....this is a DS12887 Chip if that helps....
Click to expand...

Apparently I didnt go down far enough as I finally got to the metal parts....used an old soldering iron to get through the resin / compound and to the metal. Broke the connection on the left pin. Just have to solder on the Coin Cell Battery.. Hoping the soldering iron didnt hurt the Dallas Chip, so when I solder it back to the board, it will do its part of the job!! I just got impatient from digging with the blade. Took only a minute or two to get to the metal contacts using this method. Once I was just about to the metal, I stopped and scraped off the rest with the blade. Also stopped a few times during the process when the Dallas Chip started to get hot from the soldering iron. If it works, I will know i can do it going forward if needed. If not, buy another Dallas Chip and do it the long, tedious way!!
 
+1 on the socket...see if you can find a local electronics supplier to get one from, shouldn't cost more than a buck or so even at local retail pricing (and more like 20 cents from an online vendor). I have a handful, but they don't help you there from here.

Or if you have a scrap motherboard somewhere with the same size BIOS chip, desolder the socket and use that.
 
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