Fixing the Trackpad Buttons on the 11.6" (ZA3)

Discussion in 'Modding and Customization' started by UnicornFightClub, Dec 1, 2009.

  1. UnicornFightClub

    UnicornFightClub

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    (WORK IN PROGRESS)

    One giant button works on Apple computers because they're made to need only one button. The Aspire One isn't a Mac, so whoever made the final decision on the single button deserves a slap in the face. Having one button for the left and right click with a riser in the center is about as useful as separating the buttons physically by two inches. If the words 'ribbon cable' or 'surface mount' scare you, proceed with caution. You'll need a bit of experience, a soldering iron, and two buttons (under $10 shipped from Mouser).

    I figure the easiest way to make proper trackpad buttons is to cut the button down the center and then piggyback two additional buttons (one additional for the left click and one additional for the right click) near the center. I measured about 3.2 mm clearance at the center plus the thickness of the sticker on the PCB, which we'll assume to be 0.1 mm. Scrape off the green coating at the location where the additional buttons will be added so that the SMT buttons can be soldered on--epoxy is the only other reasonable option I can think of but I doubt it would hold up to even a hundred thousand clicks. Don't forget to remove a line of copper around the leads or you'll end up with all your leads grounded--we're soldering it to make a strong attachment, not for the leads. I've got a spool of thin insulated wire (I think 40 gauge) which should work perfect and make for a clean install.

    I measured the operating force for the stock buttons to be sure the ones I add will feel the same. All I've done with the laptop so far is reinstall the OS, so right click has barely been used. Results are that the right click clicked at 160 g or 1.57 N, with the left click 5-10 g below that (I can't remember exactly). That's perfect because 160 g / 1.57 N is a standard operating force for small buttons like these. The last decision is which size button to get. Just fork up the cash and order from mouser if you plan on doing this--standard buttons are all 5 mm (much too tall to fit) and you want one that'll feel the same as the other button. Here are the two viable buttons that Mouser has (Mouser is a very popular company that sells a massive catalog of electronic components with competitive prices and no minimum order):
    http://www.mouser.com/Search/ProductDet ... 688-SKQGAB
    http://www.mouser.com/Search/ProductDet ... 33-CB315FP

    The first is 1.5 mm in height and rated to 500,000 cycles. The second is 3.1 mm in height and rated to 100,000 cycles. I couldn't decide so I just ordered 3 of each. I'm still waiting on the buttons, which should arrive this week, and this is where I'm at with the project. I'll make up for the gap between the key and the new button Unfortunately I won't be able to finish it until three weeks from now, so I'll update the project then.


    Here's how to remove the top panel and access the trackpad PCB:

    I've marked the screws you need to remove as well as which type they are (there are 5 removable types). There's only one screw I'm unsure about, and it's screw B. Since all but one of the screws on the back are the same, I didn't realize there was an outlier. I'm pretty sure the longer of the screws (B) goes at the top left, hopefully someone can check and confirm where it goes. The only screws you need to remove are those that are marked, don't bother removing any others.

    [​IMG]
    Screw Identification Chart

    1. Remove battery.
    2. Remove the following screws from the back:
    [​IMG]
    The orange ones have a clip at the end so they don't come out all the way, they stay attached to the flaps. Once everything's unscrewed remove the hard drive and connectivity flaps.
    3. Carefully detach the white and black wires on the WiFi card.
    4. Remove these three screws under the flaps (the red arrows are pointing to the WiFi wires--snap them back in gently when you're putting it back together, and be sure you don't mix up the white and black):
    [​IMG]
    5. Pull the WiFi card out and set it somewhere safe. It's probably not too static sensitive but it's always a good idea to touch something metal first when working with sensitive electronics.
    6. Removing the keyboard is the trickiest part. Flip the laptop over and open the lid. There keyboard hinges at the bottom and then pulls out, it's held down by four spring loaded clips. The trick is to push the clip back and pull the keyboard up just enough so that the clip is held in by the edge of the keyboard, it's easiest to start on the left or right side and work your way down in a row. The clips are as follows: one between Esc and F1, one between F5 and F6, one between F10 and F11, and one between Ins and Del. Here's a picture with the keyboard removed so you can see what they look like (sorry, I didn't think to take a close-up):
    [​IMG]
    Be careful with the keyboard, there's a short ribbon cable that needs to be detached before it can be completely removed:
    [​IMG]
    7. The plastic clip holding the ribbon cable flips up, just lift gently in the center with your finger nail. Be very careful here, I don't want to scare you but the plastic clips are easy to break and there's no way to fix them if you break it, you'll have to find another way to hold the ribbon cable in. There are two to remove; first the one for the keyboard so you can lift it out, and then one for the trackpad:
    [​IMG]
    8. Remove the following screws under the keyboard (the red arrow is pointing to the trackpad ribbon cable):
    [​IMG]
    9. All that's left holding the top on are some pressure clips. Make sure the marked screws are out and then pry with a bit of force on the front, the clips should release and the top come off. Welcome to the inside.
    [​IMG]
    [​IMG]
    [​IMG]
    10. I didn't label the last three screws because it was at this point that I picked up the top and moved to my desk to nothing would get in the way. If anyone can compare these screws to the others and let me know which type it is, I'll update my pictures. These three screws are the last that are holding the PCB in. The button is plastic welded on at the center but we can break it off no problem when we're ready, because the button has a ridge around the edge holding it in and it'll need to be free moving anyways.
    [​IMG]
    [​IMG]
    This view shows you what we're working with under the button:
    [​IMG]

    All in all if you have some experience the project doesn't seem too intimidating, the most difficult step was getting the keyboard off. If anyone else wants to have a shot at it, post your progress here.
     
    UnicornFightClub, Dec 1, 2009
    #1
  2. UnicornFightClub

    UnicornFightClub

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    I finally found the time to write up the rest of the project. The switches came and I decided to use the smaller of the larger switches because their rated life is 500,000 clicks as opposed to 100,000.

    First, I removed the stickers and laid out where the switches should go. I arbitrarily picked a location at about the same horizontal position as the original switches. I removed a portion of both mask and copper around where each contact was to be soldered. I used a dremel and probably could have done a better job, but it worked well enough. I etched away the mask at the center of the boxes and tinned them, then soldered on the switches. Be careful how deep you etch, the board has more than two layers and you might accidentally short a lead.
    [​IMG] [​IMG] [​IMG] [​IMG]
    Next I cut off the mouse button and cut it down the center using a dremel and a cutoff blade.
    [​IMG] [​IMG] [​IMG]
    I added a glob of epoxy to make contact with the new button and let it cure. I also added some epoxy to the contact points for the original buttons, but they ended up getting put back to the original depth later anyways because I wasn't comfortable with the buttons being that tight. I shaved off epoxy from the two addon contact points using a straight razor by trial and error until the buttons sat well and had very little play. Make sure the contact points are flat.
    [​IMG] [​IMG]
    Since the buttons no longer have horizontal support, I took off a bit more plastic where I had originally cut the button in half so that a paperclip could fit between them. I cut the paperclip to length and used a dremel to cut a trough for it to sit in between left and right click. I put the soldering iron on it for long enough to make it melt into the plastic and then melted a small amount over top to keep it in place. Remember to cut off any plastic that's sticking out or the plastic buttons won't sit flush. I also beveled the edge of the cut.
    [​IMG] [​IMG] [​IMG]
    Lastly, test with a multimeter and reassemble. Test each of the four leads with a multimeter before you start; I don't remember which it was, but I believe one of the leads was grounded while the other three were not.

    Here's the final product:
    [​IMG]


    Pressing on the left or right edge of the plastic buttons feels natural. Pressing at the center requires slightly more force and sometimes depresses both switches, but isn't a big issue. Overall the new buttons work well; it's nice to finally have separate left and right click.
     
    UnicornFightClub, Jan 9, 2010
    #2
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