After cleaning and reassembling...

Logitech M705: How to fix a defective mouse button

I’m a big fan of Logitech mice, or at least was until a few days ago. My wireless Logitech M705 started to behave strangely: Pressing down the left mouse button resulted in multiple clicks (i.e. double-clicking) and dragging became impossible due to random interruptions when holding down the button.

Without a warranty (which had expired three months ago) I did not feel guilty when opening the mouse to look for the cause. The culprit was quickly found: the microswitch of the left mouse button. Luckily, I had spare microswitches as I’m currently playing around with the optical sensors from other spare/defective mice. I will cover this in another post. To come to the point: after replacing the microswitch, the mouse works again as usual. I’ve made a few photos (a picture is worth a thousand words ;-) ) to help others during disassembly of the housing. Screws are marked red, and I have also marked (in yellow) two tiny springs that can easily be lost.

This fix has a bad aftertaste: at least in Germany, there is much talk about “planned obsolescence”, and I’m wondering if Logitech (and other manufacturers) use cheap microswitches that only survive a certain number of clicks. Especially after my mouse showed the previously mentioned defect so soon after the expiry of the warranty… On the other hand Logitech kept its promise regarding the battery life – I’m still using the first set.

Update: Just as a brief clarification, after I got some feedback on the M705. (Apparently several users have had similar experiences.) Logitech uses Omron switches that actually seem to be pretty good. So I want to point to a post from Ralf who recommends to first try resoldering the joints. If that doesn’t help an exchange might be the best option.

47 thoughts on “Logitech M705: How to fix a defective mouse button”

  1. Nice post. I’ve use various mice since the early 90s both PCs and Mac and the only double click problems I encountered is the Logitech mice I bought one year and a half ago.

  2. I have a problem developing with my m705 left click and I’m not sure if I should just ditch the unit or try cleaning it once again. I don’t have any micro-switches and honestly the lack of drag-drop + constant double clicking is getting rather annoying and quickly.

    1. Microswitches are pretty cheap (less than one Euro) and standardized, but desoldering them from a multilayer board can be quite unpleasant… I’d send you one of mine but I think this just as expensive as buying a new one.

      Before throwing the mouse away, I’d at least try to repair it. Maybe you could take the mouse apart and first try to carefully open the microswitch itself to clean the contacts. If that fails, i.e. the microswitch case cracks, you could still try to desolder it.

    2. I have had the same annoying left click drag/drop problems on my M705 mouse. I disassembled it and it did need some minor cleaning. Once I removed the scroll wheel assembly I noticed that there are two very tiny springs (nobody mentioned this) that are exposed under the front of the scroll wheel assembly. They sit in individual recessed holes – remove them and set them aside. They will fall out if you turn over the mouse with the scroll wheel assembly removed. I removed the 2 screws holding down the mini circuit board and turned it over to use a magnifying glass to inspect the micro switch solder joints. I could see that the solder joints on the left micro switch looked like it was separating and the right micro switch joints did not look much better. After soldering all three pins on both micro switches I can report that the mouse works great.

      1. Hi Ray, I actually did mention these two springs in the post and also added a photo to highlight their positions. But thanks for your detailed comment. :-) Kai

  3. Dear Kai,

    thank you so much for this article. I just had the very same symptoms with my M705.

    In my case, it wasn’t even necessary to change the micro switch. All I needed to do was to re-solder the three solders that hold SW1 in place. That did it for me.

    The reason for the failure was only a bad / cold solder. Such a failure is very common for parts that are under heavy mechanical stress, so I find it quite likely that your problem (and that of other users) was also caused by a bad solder. If this was true in your case, you actually fixed it by de-soldering SW1 and inserting another switch – witch fixed the alleged bad solder as well.

    @Marty: You should give this a try, no spare parts needed.

    At least in my case, it couldn’t have been a case of planned obselescence, because nobody can calculate when exactly a bad solder is going to break. In my case, the failure happened after less than two years, which is well within Logitech’s guarantee period of 3 years for the M705 (Despite of that, I preferred to fix the problem by myself). They would only harm themselves if they built in such a quickly developing problem.

    1. Hi Ralf,

      thanks for your comment. I support your recommendation to at least check the solder joints, after this has also been a problem for me in other cases. Resoldering the joints is easier than exchanging (especially desoldering the new lead-free solder on multilayer boards can be a PITA). ;-) In this case I had decided to exchange the micro switch as I had spare ones lying around… Kai

  4. Hi,
    I have a similar problem with my Microsoft Wireless mouse. Left Click button is not working. all other functions seems to be working. that is, right click, center click, scroll wheel etc…

    It looks like I need to change the micro switch for my left click button issue… Is the micro switch you have shown in the picture is 2-pin micro switch? or 3-pin micro switch? For me, it looks like I need 2 pin micro switch for this Microsoft mouse.

    My Mouse model: Microsoft Explorer 2.0
    Model No: 1007

    Appreciate your time.

    Thanks,
    Antony

    1. Hi Antony,

      I’m not familiar with that type of mouse and a quick web search for its interior was not helpful either.
      In my case common 3-pin micro switches were installed, but only two of the pins were used (i.e. it wasn’t used as a changing switch) if I remember correctly. I have not yet seen 2-pin micro switches, so maybe the ones in your case are manually modified (with the third pin removed)? I would recheck that if I were you.

      Best, Kai

  5. Hey, i found this article very nice. I’ve experienced same problem, quick search landed me here. I’ve had cheap mice that have had defective switch, then replaced the faulty switch with new one found in local market. Apparently the new switch has lower quality, LOL so the click feel so clacky hard and the lifetime ended so quickly.
    For my m705 instead of replacing the switch, i resoldered those switch pins on the pcb. I found that the faulty were not in the switch but in soldering tin quality (brittle and pores), seems like the problem was in PCBA line.

    1. I have two M705 that both had the problem, one in particular was so irritating I couldn’t ever select a desktop icon without (unwanted) double clicking it.

      I opened the not-so-bad one to replace switches (it still lies opened, waiting for switches to arrive.) Then I read this comment and did the “empty capacitors” trick to the really-bad-one, and wow: it worked like magic!

      So its probabaly NOT a switch problem, but you need to refresh its capacitors: ITS A DAMN CIRCUIT DESIGN PROBLEM!

      1. Hi Agelos, I’m open to every solution that might help fixing the problems of the M705 (although mine works fine so far). Maybe checking the caps before exchanging the microswitches isn’t a bad idea either. — Kai (Thanks)

    2. thanks so much dude!
      was about to get the screwdrivers and solder out..

      definitely try removing static energy!
      Simply 30 seconds and my mouse is back….

      Thanks Rostamiani,
      thanks for info Kai!

  6. Thank you for the excellent documentation you have provided for disassembling the M705. I was tearing my hair out trying to get it open without success. You showed me there are two more screws hidden under the sticker in the battery compartment.

    My scroll wheel was stuck and would no longer work as a middle button. I simply needed to open it up to free it, and it works fine now.

    However, the plastic pad on the bottom of the mouse will never be the same again, after having to remove it to access the two screws. I wonder of Logitech can supply replacement adhesive pads?

  7. I had the same button problem. I contacted Logitech customer service (mouse was less than one year old), explained what’s wrong and they sent me a replacement mouse cost-free. I didn’t even need to return the defective mouse.

  8. Hi Christian!

    Thanks so much for this article. I couldn’t find the instructions on how to dismantle the M750 anywhere else.

    Can you remember, if the microswitches used for the two lateral buttons (those that are often used to go back and forward in a browser) are the same as the ones for left/right clicking? It’s not quite visible from your photos.

    I dropped the mouse and damaged one of them, but I don’t think they’d replace the mouse in terms of guarantee. It’s also quicker if I replace them myself. Then again, I don’t want to loose the guarantee by dismantling the mouse just to have a look, in case I needed it for anything else.
    Can you help?

    Thanks!

    1. I’ve just repared my mouse, so I will respond to myself here.

      The microswitches used in the side buttons (defaultly back and forward functions) are different from those used for left/right clicking.
      It can be found here http://www.gme.cz/p-b17310-p630-143, which is also where I bought it, but I found it also in another shops, so it seems to be pretty common.

      Hope this helps someone.
      M

  9. This page has a great collection of links, for me this one helped me solve my clicking problem: http://www.redferret.net/?p=31008 . Thank you Steve for posting it here! Also, I have found that if you contact Logitech Support even after your warranty has run out they are willing to help, they actually sent me a replacement mouse free of charge a couple of months after my warranty had expired. Worth a shot I’d say.

  10. Thank you very much! It helped me a lot. I’ve a M705 and the button to switch between the mousewheel modes wasn’t working. So I disassembled it and fixed it.

  11. Thanks very much! Can you imagine working on Photoshop with an erratic left button. How do I take out the bolt holding the scroll wheel. It seems to come out but gets stuck.

  12. I have a similar problem with my M705 mouse, I dropped it by incident and after that it acts very strange – when I click with the left mouse button it performs something similar to a middle click or double click… but I’m not sure if it can be fixed.

  13. I have changed the microswitch, and it works fine right now. It was not easy, molding metal needed over 300 C deg to melt, and was hard to pull the switcher out. But now I have different problem. For the sake of safety I gently removed laser wire, to get better access to the back of the main chip. But later I have learned it is not that easy to push it back. No my mouse have lost its precision completely. Anyone have tried to mess with laser wire? that brown flat one… Btw my mouse is almost 4 y.o. So no warranty and I decided to fix it myself.

  14. I had the exact same problem as you did, except that my 705 lasted a bit over three years. I opened it up, blew some compressed air into the switch to remove any possible dust and now it works just fine.

    1. Hi Ben, nice post about the repair process on your mouse button. I was a bit amused by your post about the USB Floppy drive. I’m also having one lying around and it recently became helpful when recovering some files for a friend… ;-) — Kai

  15. Replacement of the switches did not last long for my mouse. De-bouncing of buttons is usually done by a time delay in the firmware, so I also suspect planned obsolescence here. Instead to replace the switches a third time, I now soldered 100nF condensators (blue or yellow ceramic blocking condensator) parallel to the contact pins (the 2 pins close to the white push button). Works fine, wonder how long this will last.

  16. I dropped my M705 about 1/2m to the floor. The next day I realized that something went strange with it. Was about to think about a new mouse, but tried it on another computer with Logitech software installed. I realized that the “right scroll” switch seems to be active all the time.

    Your post helps me to confidently open the mouse. Thank you for that!

    Though my “left click” and “right click” micro switches are working perfectly, the “right scroll” switch seems to be pressed all the time. After looking a while for broken parts I just pushed the wheel housing a little bit harded – and suddenly the hole thing was set again. I can’t figured out exactly where it got stick before, but now it is working again as supposed.

  17. 10x for posting this. I just disassembled my M705 based on your photos and exchanged the switches. So far so good.

  18. What do you think about how to move the laser-sensor to the geometric center of the mouse? Under the wheel closer to the battery compartment there is a place for this? I was serious.

    1. Hi Toren, I was always wondering why Logitech did not do that right-away… I mean: I DO recognise the shift in the position of the sensor. The only big minus I see for this model. But I’m not sure if that would be fixable as the internal firmware might somehow have code to compensate with this misalignment. Not sure what happens if the absolute position changes but the internal ‘correction’ stays the same… — Kai

        1. Hi, I’ve just taken a look at your drawing and I think the main problem will be the ribbon cable from/to the optical sensor. It might need to be extended. Also the firmware of the mouse might be specially adapted for the laterally placed sensor (but I’m only guessing). — Kai

  19. I had this same problem with 2 M705 mice and found that it is common with all brand mice after regular daily use. A friend said he fixed his by whacking it on his palm real good, so I gave that a try and it fixed both of mine. Much easier than diss assembly. I take laptops apart and fix boards and sockets for a living, I didn’t want to have to take something else apart. Hope this provides an easier fix for people that don’t take things apart to fix them.

  20. Awesome page. Resoldering my micro-switch contacts has allowed me to select, drag, drop reliably again.

    Many Thanks!

  21. I programmed my Logitech mouse so that pressing the wheel on a link opened the link in a new tab. After 4 or 5 years the wheel push has become harder and harder and more and more unreliable. Reviews are critical on the useful life of Logitech mice. Rather than buy a new one, I have reprogrammed the mouse so that a push to the right on the wheel on a link opens the link in a new tab. Works perfectly now – although it’ll puzzle anyone else using my computer.

  22. Thanks for this info! It would have been a huge PITA disassembling my M705 mouse without it. My mouse is also showing the same left click problems. I’ve resoldered the joints to see if that fixes it.

  23. Spray WD40 is magic for many problems, inclusive volume wheel in headphones with rac rac rac noises, also for repair this problem of mouse clicks…

    Test, is a very fast, not need open the mouse or open the headphones, spray and go well another time…

    1. I use WD40 (or Caramba) from time to time myself and it can really be a problem solver. I still would be careful in case of micro switches as applying such lubricants may cause more harm – even more dirt can be washed into the switches with them if wrongly applied. — Kai

  24. Hi guys,

    I just wanted to say thank you to KAI for detailed instructions. My problem was a bit different. My right button got stuck. It was not due to faulty micro switch but a small part of foreign plastic got stuck between micro switch and button. I had to disassemble the mouse a bit further to reach and remove the plastic part. It works great again!

    Thank you !

  25. I have never had any problems with mice until I made a mistake and bought couple of cheap wireless mice (all made in China). They worked OK for most part but first thing to give up with all of them was the scroll wheel/middle button. Either wheel scrolled pages in erratic manner or middle button act like I would click it several times even if I only clicked it once. And that’s because they use cheap potentiometers and micro switches with wheel/middle button. Two other buttons work fine but they use different kind of micro switch.

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