[weblacky]

Hi All,
I have several new posts to make (formatting will slow me down and so give me time) regarding small SGI fixes and hacks to share. I decided to do this one first because I found very little info online on the correct position of the battery cell connections on the DS1286 chip used in the SGI Indigo2 line of stations. So this post will show you where those positions are and the easiest way I found to drill them!

I choose the battery holder due to shape and appearance, I realize I could have done more creative stuff with the wire being run, I'll consider better paths next time.

The wire used is a 20 awg silicone stranded wire from Amazon, I liked working with it...I was extremely tempted to actually put a JST connector on the chip run a battery holder elsewhere in the station chassis to allow a much easier time checking voltage (with a multimeter) and replacing the cell. Ideally I'd love to do this without removing the cover. So anyone who has a recommendation for positions on the rear or inside the drive bays, please let me know. I'd love to just keep replacing the batteries without having to "deinstall" the system every 7-10 years or so.


Also please note that I'm using a Dremel 4000 with the 561 spiral cutting bit. This bit (running just a hair under setting 10 on the dremel) went through the chip epoxy so well, it was just a challenge to do it in layers so I wouldn't damage the battery connections when encountering them. I highly recommend you get this bit and use it as shown in the pictures for best (minimal) results!

Here is the picture showing the final regions needed to be drilled:



Here is the technique (orientation) I used to do the drilling, press downward into the epoxy as well as a small amount of side-to-side to dig into the epoxy with ease.



Here is the cutoff technique I used to cut the battery connection! Most of these chips are not dead, they are just very low in voltage (lower than the 3V required for operation). Use that to check the battery voltage BEFORE plunge cutting! I got just over 1V DC when I did this, that confirmed polarity and the correct regions. After plunge cut you shouldn't read any real voltage. So use the measurement before and then after to confirm you've cut your connection (on one side only) on your battery.

After you expose both metal regions, tilt the bit as shown and attempt to gently plunge, this will cut the extremely narrow connection at the top of the left region! You can tell if this worked by using the multimeter technique described above.



Then you can solder up a battery to it, I found the negative to be on the left side...but please use a multimeter and scratch-in the polary into the side of chip to remind yourself, wiring it backwards will surely damage the chip permanently.

here's the picture of my final result:



I have a few more picture here: https://flic.kr/s/aHsmFc4NKB

The gallery should be public and viewable (let me know if it's not). I've not placed this into a system yet, and I thought of doing several more chips (I have two more chips to play with). But I fully destroyed a chip before, trying getting the entire cell battery out, so I'm 100% of where the battery connections are and which ones are where. Do not attempt a cutoff on the right side, there's a ring of metal that touches the side of the battery that forms the positive post, it's a huge piece and you'll be cutting into the cell for sure. The side I indicated is much much smaller in mass than the battery housing on the right. It's much easier to attack the left (negative) pole connection to cut the battery circuit. I ruined a whole chip (might take a picture of it one day) to be 100% certain.

Thanks and good luck to anyone that tries it!

-Josh

[Dylanear]

Great post! Thanks!

Last time I had a Dallas RTC go on me I just bought a new one! That was probably 2006? But one day, I'll be pulling my old machines out of storage and I suspect this will be needed!!

[weblacky]

Thanks,
Yeah, the DS1286 chip hasn't been produced for like 10+ years. You can still find working ones on eBay (used pulls). I've not found NOS, and even so...batteries will still be old. Some of the RTC chips used in some SGIs are still made, but I think most of the older model (Indy, Indigo2) RTCs are no longer in production and have no compatible variant, that I know of.

[Dylanear]

Yeah, even a working one will only keep ya going for so long. They are all going to need to be modded before long. The replaceable battery is the way to go.

I just want to see about doing it as clean looking and as reliable as possible. Kind of hoping someone will make a side business out of selling these modded really nicely.

[NoodlesMcPastaMan]

Mine still works, for now. But this will be handy to reference in the future!