RandomHowTo - SGI Indy Dallas Battery Replacement

If you own an SGI Indy then there are three things that you live in fear of...

  • The hard drive expiring with a symphony of ticking
  • The power supply generating magic smoke instead of electrons
  • The internal battery in the timekeeper chip dying

Of these the power supply is the hardest to recover from, but the SCSI hard disks can be replaced with more modern alternatives. While the timekeeper chip is straightforward to fix with the right tools, the potential for things to go wrong is significant.

There are a two or three really good web pages with information about this, but I approached the fix in a slightly different way and thought I'd put some notes and photos up that might help someone else. If you look at my handy work here and think 'no way!' then don't panic, you can get replacement chips online but be warned - they are becoming rare and expensive.

Before I dive into this, how do you know the battery in the Dallas chip is bad? Even before you get to the GUI, you'll see a message along the lines of ...

... and when you get to the GUI, among others, you'll see this message ...

So it looks like we have a Dallas chip to fix. The process of doing this runs something like this:

  • Open up the Indy's case and remove the Dallas chip from the motherboard without destroying it.
  • Locate which end of the Dallas chip has the battery in it, cut open the body of the Dallas chip and expose the internal lithium battery without puncturing it and/or destroying the chip. Power tools will make this more fun.
  • Pry out the old dead lithium battery without ripping off either of the flimsy metal contacts that are fused to the top and bottom of the battery as that will probably destroy the chip.
  • Solder a new battery to the contacts in the chip without heating it up too much, getting the contacts round the wrong way or shorting anything out because this will destroy the chip and probably your Indy too.

Lets begin!

Unplug everything from the Indy and remove the blue plastic case. If you've never done this before, put your Indy on a table with the front facing you. Reach over it to the black tab at the rear of the case and gently lift it with your left hand and apply pressure on the blue bit of plastic protruding from the back of the case with your right hand. The case should slide forward and off the metal frame without the need for any excessive force.

Inside the case, look for the hard drive. The Dallas chip lives on the edge of the motherboard closest to it, right next to the power connector for it.

Before you remove the chip, make a mental note or take a photograph of which way round it goes. Those little triangles you can see on the chip and on the motherboard are there for exactly this purpose.

To remove the chip you can use a chip puller but the large body of the Dallas chip is actually a little too deep for it to get a good grip. I ended up using my fingertips to rock the chip gently back and forwards along the short length. You'll feel one side 'give' and become loose. slip your fingertips under the corners of the chip and squeeze upwards to remove it. Do not use a screwdriver or anything to pry it upwards as this will likely damage something on the motherboard.

On my chip, and the other images I've seen the battery is under the 'dogs head' graphic on the chip. I checked this with a magnet and it was pretty obvious that you could pick the chip up with the magnet at one end but not the other. The metal is the battery so that's the end to cut.

The next step is to remove the plastic and expose the battery. It's important those pin on the underside do not get damaged, so I put a small spring clamp around the chip to support it and give me something to hold.

I sketched out a circle on the top the chip in pencil, then took my dremel tool with a 'ball carving' bit and pressed it into the top of the chip on that pencil mark, until I could see I had reached metal - the battery. I then followed the pencil mark around before 'joining the dots' and used a small screwdriver to pry out the middle bit of plastic.

That contact is the positive connection and while it's quite wide where it is joined to the battery, it narrows to about three millimeters just where it disappears into the plastic so care is needed not to snap it. I lifted the end of it away from the battery, folding it up where the two dots are on the photo above. I then took a small pair of pliers and gripped that tab, rotating it against the battery (away from the word 'timekeeper') until it released from the battery. I then gently pushed it up and away from the battery being careful as this was at the narrowest part of the contact.

From the images I'd seen of the chip I knew that if this contact was at '10 o'clock' then the other contact below the dead battery was at '8 o'clock'. I also knew that the depth of the battery would mean the the lower surface would be approximately halfway down the side of the plastic body. I decided to deepen the groove I had made around the battery first, then remove the side of the case (between 7 o'clock and 4 o'clock).

I'd exposed the side of the battery, but when I tried prying under it with a small screwdriver it wouldn't release. I widened the 'incision' to the side of the case, keeping in mind there was a contact on the left hand side of it which I could not damage. This allowed me to move the battery slightly upwards and create a small gap under it. I was able to see the contact and slipped the blade of the screwdriver under the battery (at about 7 o'clock). I thought this would let me break any bond between the battery and the lower contact but there didn't appear to be any physical connection as the dead battery popped right out.

Some people have used battery holders for the replacement cell - the CR2032 (3v) seems to be the preferred choice. I did have a CR2032 to hand already but it had a couple of wires connected to it so that's what I went with. If I need to replace the battery again, I have a couple of long wires to attach to a fresh cell or holder.

I soldered the negative (black) wire from the battery to the lower contact, first slipping some wide heat shrink tube over the wire. I then carefully shrunk that over the contact working for a few seconds at a time to avoid cooking the chip. I then soldered the positive (red) wire to the upper contact and folded it back on itself to ensure it was below the original surface level of the chip. I also used the dremel one last time to cut a small slot for the wires to exit through.

I then broke out a pack of black sugru and did a repair on the body of the chip, replacing the plastic I'd removed and making it a little more presentable. This was allowed to cure at room temperature for 24 hours.

Once the sugru had cured, the chip was reinstalled. I did need to slightly straighten two pins at one end of the chip before I did this. Light pressure is all that is needed to re-seat the chip in its socket.

That's it for the hardware side of things, but there are a few commands yet to run. I'll update this post once I have that covered off.