Fixing What Ain't Broke
I was recently given a Dell Inspiron netbook. It's a pathetically under-powered thing with an AMD E2, 4GB of RAM and 32GB eMMC. It could barely hold and run the Windows 10 installation it came with, and even Ubuntu was a struggle. It needed some upgrades. More memory, better storage.
Upgrading RAM was easy — it supports up to 8GB of DDR4, and I just happened to have a compatible card laying around.
Storage was harder. While this series of netbook did have models that supported SATA hard drives, this particular unit didn't have the SATA port populated, and was missing a buffer and some passive components as well. Clearly not a viable option without schematics, BOM, and a hot air rework station.
This model also didn't have an M- or B-key M.2 slot for an SSD. All it had was an A-key M.2 slot for a WiFi+Bluetooth card.
A-key M.2 provides a single PCIe lane and a single USB data connection. Usually WiFi will use the PCIe lane, and Bluetooth uses USB. It's not ideal, but an NVMe SSD can work on a single PCIe lane. It should still be faster than eMMC.
The problem of course is an M-key SSD will not physically fit in an A-key M.2 slot, and it would require sacrificing WiFi. What good is a netbook without the 'net?
The first step was to get an A-key to M-key M.2 adapter. These aren't too difficult to find, but unfortunately none seem to break out the A-key USB signals.
I also picked up a cheap USB WiFi adapter. Sure, it was small enough I could have just left it in one of the USB ports, but I wanted a clean, invisible installation. I didn't like the bright LED on the WiFi adapter flashing, and I didn't want to risk snagging it pulling the netbook out of a bag.
So after confirming WiFi worked in Linux, I tore it apart and set about finding a way to install it internally.
Power for the adapter was easy — I just had to wire it to the power/ground terminals on one of the existing USB ports. I could have wired the USB data the same way, but then I would have had to remember not to use that port. It would be far better if I could use that USB data connection on the A-key M.2 slot.
The first thing I tried was soldering wires directly to the USB pads on the M.2 adapter board. It was some of the tiniest soldering I've done in a while, but lots of flux got me through it. Unfortunately it didn't work. There just wasn't enough of the pads to solder to without disrupting their connection to the socket. I never could get a connection all the way through.
Time for a new plan. There wasn't enough room on the back of the M.2 socket to solder wires to, so I traced the signals back a little ways until I found some test points.
These test points are tiny — far smaller than the pads on the M.2 edge connector. Thankfully though, they were spaced far enough apart I could solder to them individually without bridging the two.
It's certainly not the prettiest solder job, but it works. I'll probably come back later and add a dab of glue or clear lacquer to help hold the wires in place.
In the end, I consider this project a success. I upgraded the memory and primary storage without sacrificing WiFi, and from the outside there is no evidence of any modifications. That E2 CPU is still nothing exciting, but with a fairly lightweight Linux distribution like Xubuntu, it's a decently usable little device. It'll do just fine for some lazy weekend browsing.