Sunstorm Labs Blog

My Logitech G15 got wet again and none of the keys were working. The logical thing to do, then, is to take it apart and try to figure out what’s wrong with it.

Note: Don’t try this at home. It WILL irrevocably void your warranty, and you can easily cause permanent damage to the keyboard.

First, we need to unscrew all the screws on the bottom plate. The top plate is also locked down by a bunch of plastic hooks, which can be pulled back with the help of a thin screwdriver. Be careful with the silver plastic, since it scratches very easily.

The LCD is attached to the top cover with a small FPCB to the main circuit. It can be removed by pulling up the little clamp that holds it in the socket.

All of the important electronics are at the top of the keyboard. It’s rare for the electronics to break during a spill since most of the water gets on the keys themselves. Our next task is to remove the silver plastic panel, the one on which all the keys are.

First, it has to be unscrewed. The clear plastic bits that go under it also unscrew at the top, and the FPCB connections can be carefully detached by easing them out of their sockets.

Again, there are plastic hooks holding it in place. These are easier to go around. The bottom ones can be released by bending and twisting the keyboard a bit, and if not there are a handy set of holes one can use to get to them with a thin screwdriver.

This should get the keyplate separated from the keyboard.

Underneath it, we can see a clear plastic plate and the LEDs used for backlighting the keys. Some of it’s wet; I’m on the right track. The real problem lies under it though, so lets get that off too.

The backlighting LEDs and their circuits sit in the gaps in the plastic. All those litle white dots diffuse the LED light all over the keyboard.

Beneath it, we have a flexible PCB printed on a transparent substrate. This is what detects keystrokes. It’s made up of three layers. All those little lines are a very thin layer of conductive material. The middle layer is just a separator that keeps them separated until a key pushes them together. Every top-bottom combination is unique, and when they’re connected, the keyboard can figure out which key’s being pressed.

What pushes them together is this rubber membrane, which also makes the keys pop back up after being pressed.

The problem with this, is that these FPCBs are extremely easy to erode with liquids. Having killed a Saitek Eclipse keyboard before by spilling stuff on it, I already know what to look for…

Dirty, dissolved or corroded connections. This spells doom for all any any keys that they connect to. I’m still trying to find a good way to clean these that’ll keep them intact, and I’m not sure if it’s even possible. A wet cotton Q-tip seems to do the job, but it’s important not to use any cleaning products, because they melt the connections right off.

They can be easily tested with a multimeter. Most have a setting that will beep if there’s a connection.

Those top connections are definately dead. Just my luck, these control the space bar, the letters A, Z, and parts of the keypad. Not exactly ignorable.

I’ve called Logitech, and they don’t sell separate parts. So I either fix it, or get a new keyboard.

Last time, I tried to repair the Saitek using liquid silver. However, the way it is, it’s hard to apply and takes ages to dry, and, well, didn’t work. This time I want to try a silver ink pen, which is claimed to be the same, but easier to use.

I’ve ordered one off eBay. While it doesn’t come in, I’ll be using a generic crapo-cheapo keyboard.

Exciting conclusion coming soon.