Installing a USB Keyboard into an OLPC XO Laptop, Phase I

Step 7 Make a Big Scary Hole

After you've gotten your new keyboard controller down to size, the really bad stuff starts happening to your XO. The controller card was plenty skinny to fit into the quarter-inch thick keyboard case you threw away in step 2, but the XO's base is amazingly (depressingly!) thin. Don't despair, just make another hole.

This time it's going to be a keyboard-controller-sized hole in the steel plate the keyboard's sitting on. The hole will offset some of the thickness of the controller so the XO's case will actually close again. Yay.

Align the card more or less with the ribbon cable, trace around it, then cut along the dotted line. Add an extra opening for the ribbon cable so it doesn't get crunched up against the card. I used four Dremel wheels cutting mine. Hopefully you can do better. Make sure you de-burr the edges, especially around the extra space you gave the cable, so any contact it has with the steel is nice and smooth. If you want to be extra safe, cap that steel with a piece of cello tape.

Dremel away the "ribs" running along the inside of the case opposite the controller card, so that the card will have a little more room on that side, too.

Run the USB cable up and out of the case, following the trackpad controller cable, and stick everything back into place. I used plenty of cello tape. Isn't it lovely? Luckily nobody will ever see this again.

Your job is done! Call in your closing surgeon to reassemble the XO. Do remind your colleague that the stitches will have to hold extra tight, because the patient has new and bigger guts. I'd recommend feeding the USB cable around the hinge and leaving the hinge cover off for now.

Comments

[pen_sq]

First of all, brilliant project! I tried going the easier route by doing minimum damage to the steel plate, and pushing the keyboard PCB deeper. I probably ended up taking longer than you for it, But if we were ever to joust with our XO's, I believe I'd win. On the plastic side, I made a hole in the case to accommodate the controller on the PCB, and ground away little divots for the capacitor, SMT parts, and taller solder points. Carbon paper would probably help with this, sadly, I didn't have any. Use a strong light to get an idea how thin you've cut into the plastic. I plan on plugging the square hole with Shapelock after assembly. I started out drilling the plate more randomly than through actual scientific measurement, and ended up with an oversized slot for the metal-can crystal to stick out of. I also made a more directed slot for the ribbon connector. The holes are made with a drill press, using dremel abrasion discs and conical grinding stones to smooth them out. At a first test fit, I found the crystal to be a little tall, so I wired it a bit off to the side, the keyboard still seems happy with that. I ground a shallow into the case for it, The stupidly large slot for it is something to be AVOIDED in the future. Finally, I haven't finished mine yet, I hope nobody else beats me to some fatal flaw in my little variant.

[labelreader]

Cool! Looks like you found a better way to do it! Let me know how your case closes; it would be great if you get a better overall fit out of this technique! A little bit of putty never hurt any project. ;o)

[pen_sq]

OK, I have mine together, and found I got the keyboard centered wrong. The top row of keys binds up, so I get to take it all apart again. The top plastic edge is TREACHEROUS - I test fit the top panel many times, but it still went wrong on me. I have the keyboard well glued to the steel plate, so I guess I'll just skim a bit across the top edge with a dremel, and repeat. My drill press (+ XY table) died earlier, so keeping a straight edge will be a hoot. Since I'm on the hook for a re-disassembly, I get another chance to snap some more forgotten pictures of the insides. I found that putting a loop-de-loop in the ribbon is a nice way to shift the end sideways without making a mess of Horrible creases. I sandwiched a double-stick foam pad inside the loop to ease the creasing stress a bit, too.

[pen_sq]

I bet mine was a bit more difficult to get back together - the USB board has to be taped to the back of the plate just right before heaping/hooking/sliding the back panel into place. It was not fun the first two times, and I don't expect it to be better the third. After putting it all together, I found the keyboard to be a flake. Sometimes it would send lots of +++++'s, sometimes the shift key would be mysteriously stuck, and eventually clear. My first suspicion is that the keyboard really needs the ground spring connection to it's board, so I'll open it up and wire that. Another 2 possibilities are that the ribbon connector shifted crooked, or it isn't a full plastic sandwich and is shorting against itself. Aargh!

[pen_sq]

OK, I got around to attaching the ground, and YES, it is that important. I replaced one of the marked short screws with a regular one to hold my ground line, I'm glad they threw in extras! So, now the keyboard works fine. I updated the XO's OS to the latst joyride, and there are still issues with the kernel oopsing on resume from short-term suspends (see this bugreport).