00 subject
Our patient tonight is the NVRAM (real-time clock, serial number, and preferences) chip from a Sun Microsystems Ultra 80 workstation. The little plastic carrier around it serves to make it hard to plug in backwards and easy to remove.
For reasons unfathomable to anyone with common sense, Sun decided to store the system serial number on a battery-backed chip, as opposed to permanently setting it somewhere (in a serial EEPROM, perhaps). So, when your computer gets old enough to outlive the battery, you can't get on the network anymore. These chips are obsolete and sell at about $16/ea and will have significantly reduced battery life because they're all old.
Fortunately, the battery in there is a plain old 3V lithium cell, so we can replace it. Let's dive in!
01 sawing
Here's the NVRAM chip in my miter box getting its cap split open.
The bottom half or so of this package contains the actual NVRAM circuit chip, and the top half is divided into resin-filled cavities holding a battery and a quartz crystal. We're going to completely remove the part with the battery.
The idea is to saw through the top of the package at its centerline to the top of the carrier (which is about where the battery compartment stops and the chip starts).
02 scoring
Now, I'm scoring along the edges roughly where I suspect the bottom of the battery is. This needs to be a pretty deep line because I'm about to do something brutal.
03 splitting
Putty knife in! Now to smash the pommel of the knife with a hammer until the package pops open.
Take turns on both sides of the package. Once the blade of the knife clears the outer edge of the package, it'll move differently.
04 open
And there we are! That little strip of metal is the negative lead for the battery; there's another one near the outer edge for the positive lead. I'm going to snip them so I can remove the battery.
Note the bottom of the resin-filled void. My placement of the score and putty-knife was very lucky.
05 ready
What a mess! First, I need to clean that up with an X-Acto knife and clean up those two solder pads nearest the camera.
06 one-solder
There we go; cleaned up a bit and with the positive lead soldered in.
07 hotmelt-insul
Negative lead is soldered in, and they're insulated from each other with hot-melt glue. It's the duct tape of the electronics-bodging world.
08 holder-soldered
There's our coin-cell holder soldered in with a little insulating hot-melt for extra safety.
09 holder-hotmelt
And a little hot-melt underneath. Rather looks like the Millennium Falcon, eh? It'll run the Kessel BIST in under 12 gigacycles!
10 back-together
I had to re-do the hot-melt job to get the package to fit back in its carrier. Now it just looks like some sort of embedded listening device.
11 in-circuit
That's how it looks back at home. This is a nicely-configured Ultra 80: four 450MHz CPUs, 4GB memory, and an XVR-600 graphics card. If you needed to run Solaris, this was the absolute fastest you could do in 2003 or so.
A little dorking around at the OBP prompt and we're good as new! Better, even; in 2027 or so, I can just replace the battery!
e3k-clock-board
Here's another upgrade job--this time on an E3000 clock board. The process is the same, but the coin-cell holder needs relocating because the profile of the board is so slim.
e3k-io-board-overview
Upgrade on an E3000 I/O board board. The process is the same, but the coin-cell holder needs relocating so as not to block the sbus slot.
e3k-io-board-profile
Another view of the E3000 I/O board board. See how little room we have before we interfere with an sbus card?