Sunday, December 16, 2012

Replacing the middle button on the Logitech M570 Wireless Trackball (or, yes, I really do love this trackball that much)

I've been using a wireless trackball for a while now, and it's turned out to be one of the best purchases I've ever made.  It's especially excellent for working on the train, since i don't like the trackpad and there isn't room for a normal mouse.

The wireless trackball I'm using is the Logitech M570.  It has a combination scroll wheel/middle button; however, over time this button began to get flaky.  There would be weeks where the button wouldn't respond at all, or would only respond to exceptional force. Looking online, this seems to be a common problem; the device is somewhat cheaply made, and the middle button is not the usual high-performance switch, but some lower-quality part.

I set out to determine whether the button could be replaced; I was successful, and my procedure for replacing it is outlined below.  The new button is slightly stiffer than the old, but it works consistently.

Button Replacement Procedure

Disassembly

First, pop the blue trackball out.  Then, there are five screws holding the shell together; remove them.  Note that one of these screws is beneath the sticker in the battery compartment (shown below).


With the shell off, you'll need to remove the circuit boards.  First, detach the ribbon cable leading to the trackball reader (the gold bit in the middle of the image below); to do this, you'll have to pull up the plastic locking connector.  Then, remove the four screws which keep the circuit boards on the lower shell, and pick up the circuit board assembly.  Take care not to bend the battery wires as you remove them from the lower shell.  The middle/scroll wheel button we're going to replace is just in front of the ribbon cable.



Old Button Removal

In removing the old button, we need to be careful not to damage the rest of the circuitry.  Note that our task is made easier by the fact that we don't care what state the old button ends up in.  The method I used to avoid damage to the surrounding circuit is shown below; first, I used a diagonal cutter to cut the two forward leads on the button.  Once this was done, I gently rocked the button up and down to weaken and then break the remaining two leads of the button and remove it (I did not cut these leads, as there were difficult to access without risking damage to the rest of the circuit).


Once the button is mostly removed, I used copper solder wick to clean up the four holes that the leads of the button formerly inhabited.

New Button modification and installation

If you were paying close attention during the old button removal, you'll notice that the leads were pretty much vertical.  The buttons I had on hand were very similar in size and function (normally open, leads paired length-wise); however, their leads were gull-wing SMD style (MOUSER link).  Before I can install it, I need to manipulate the leads into a more vertical configuration, detailed in pictures below.


First, push the leads down.


Then, use pliers to straighten the leads downward.


Then, gently insert the button into the cleared holes and solder it into place; be sure that it is flush with the surface of the circuit board.




Re-Assembly

Just reverse the steps in Disassembly.  It is important to make sure that the little plastic power button in the lower shell is lined up with the switch on the circuit board before screwing everything back together (the switch is the silver-and-black affair on the lower right of the picture above, just in front of where the battery clips attach to the circuit board).


It is interesting to note that Logitech uses Nordic Semiconductor radios for their wireless links (at least for the new-ish unified receiver).

12 comments:

  1. The only switch Elfa stocked in the Gothenburg store is Alps SKHHAJA010. The data sheet says that the operating life is 1,000,000 cycles. That sounds OK. I bought a couple as I needed to replace the switch on my V470 too. On the 470 Logitech used a Omron B3F switch, and on the 570 Logitech used, surprise, a Alps SKHHAJA010. Exactly the same switch I bought, which supposed to withstand 1 million cycles...

    ...I guess operating life in switches is like MTBF in harddrives since the Omron switch were typed at 1 million cycles too.

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  2. Hi, could you identify (or help identify) the switch used for the Left Button on this device? Many thanks.

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  3. The left, right and middle buttons are Omron D2F switches, most likely D2FC-F-7N which are available on Amazon, and from digikey and other electronics suppliers online. There are other switches in the D2F family that may work, you can check the pdf from Omron themselves here:

    http://www.omron.com/ecb/products/pdf/en-d2f.pdf

    Be very careful when desoldering them, its easy to damage or destroy the copper pads surrounding the pins if you heat them up too much or for too long (guess how I know that!) Use a solder sucker and wick then keep the iron on the pins themselves as you pull it out with pliers. Discard the desoldered one, it will only lead to heartbreak if you reuse it (see below.)

    Also when soldering the new one on make sure you're using a good iron that's clean, and ready to go. Pay careful attention to the spec sheet I linked for the details, solder up one pin at a time and then walk away for a few to keep the thing cool. I've replaced these things only to have the new one fail a few days later before finding that out.

    Supposedly there are also compatible cherry switches available but not having used those, I can't say if they're any better in any regard.

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  4. Very good advice, Randy (though I wonder if you meant to say that only the left and right buttons were Omron).

    Did it seem like destroying the old switches in-place before desoldering them might help with minimizing the potential for damaging the board during removal?

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  5. That's correct, I was momentarily thinking of the BB18 which I'm using at the moment. I'm actually trying to stuff the guts from the m570 into a bb13 since the profile of that is much more comfortable.

    I hadn't thought about attacking the old buttons from the top down before desoldering, that might work and I'll test it out on a spare when my replacements get here :-)

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  6. Five, five screws . . . Ah ha ha ha

    Ha - that elusive 5th screw, thanks.

    I will purchase a couple of spare switched, but for now, a tiny amount of WD40 spray has done the trick.

    Again thanks for the 5th screw!

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  7. Off topic comment here, but it's the closest thread I've found to what I want to do.

    First off, this is the best mouse I've ever used. I've been using various versions of the M570 for almost 15 years now and it's always been amazing!

    I use this mouse for gaming and want to modify it to include more buttons. I've been considering a solution that integrates a completely separate communication lonk to the computer, but just had the realization that the interface probably has more I/O available already, just need to tap into an available I/O pin(s) on the chip and pray that the drivers support more buttons already.

    Anyone know which uC is used in this mouse? I'll open it up and check soon, but figured I'd ask to get a head start...

    -Walker

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  8. Big thank you for identifying the location of that screw boss under the battery compartment sticker.

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  9. I managed to resurrect my middle button by placing a blob of blu-tack on the switch. The button worked only when I pushed real hard on it, so I figured this might do the trick, and it did! Might be a quick workaround without the need for soldering, just needs opening up the mouse.

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  10. Thank you for this - I would never have found the fifth screw without your guide.

    After a year of use, the middle wheel got very sluggish and hard to press. After opening the case, I found that the problem was a big hunk of fluff that was jammed under the wheel. Cleaned out the interior and the M570 is good as new.

    These trackballs are the best. I bought my first one after a Web design project left me with a very painful "mouse elbow." The pain went away completely, and I now own two M570s, one for the laptop. I like that you don't need any kind of mouse-able surface; you can put it anywhere - on a thigh, on a blanket while reclining and watching videos or sports, etc.

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  11. I know this is an old thread, but I wanted to thank you for the very clear instructions for disassembling the M570. My wheel just needed a good cleaning, and I am back in business!

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  12. Just bought this trackball and the trouble I am having is the middle wheel button is so hard to push compared to the Microsoft trackball. Wonder if there is a problem or if I can modify this some how? guess I will have to take it apart to find out.

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