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I have a Razer naga Left Handed 2014 mouse with a broken scroll encoded and failing primary click. It's old, but they don't make left handed mice any more so I wanted to try and repair it. I changed the encoder, which is just a JST connector - this was a straight swap and worked immediately. However, the left and right click buttons are D2FC-F-7N(10M) switches. I bought a like-for-like ( https://www.amazon.co.uk/dp/B07L2SWCZK ).

I desoldered the old switch and replaced with the new. You can see there are subtle differences, but they are (or at least should be electromechanically the same):

mouse topside, showing the new switch

Starting with the working switch (2 in the picture), I was able to identify continuity by putting my COM probe on the JST connector below the left switch (1 in picture) and the outermost pins of switch 2. I was then able to get continuity from the middle pin of switch 2 when the switch was depressed:

Mouse underside, labelled to show connections

Following that same logic I can also confirm continuity on the outermost pins of switch 3 at all times, and from the middle pin when switch 3 is depressed.

As far as I am concerned this confirms an electro mechanicaly connection between the new switch and the board. However, when I plug it in I get no response from the switch.

My questions:

  1. Is it possible that the mouse can detect an after market switch (I would be very surprised, but it might be possible).
  2. Is it possible that despite being the same model, this has some tollerance differences that the mouse can detect preventing normal functionality (whether that is due to an anti-repair defence or just due to the switch not outputting the expected voltage to the circuit)

I am at a loss. If anybody has any suggestions as to why the switch is clearly functioning in the continuity tests, but not when connected to windows, I would be very grateful. Equally, If anybody has any suggestions of things I could try I would be equally grateful.

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    \$\begingroup\$ The mouse cannot detect an "aftermarket" switch. You likely just did not solder the new switch carefully enough and there are short circuits or the PCB is damaged. Or that wasn't the problem to begin with. Did you check the new and old switch have the same pinout? \$\endgroup\$ Commented Oct 23 at 20:13
  • \$\begingroup\$ I did check the pin out yes and it was the same - PCB damage from desoldering was my suspician as well, but I figured the continuity wouldn't be there across the board if that was the case. \$\endgroup\$ Commented Oct 23 at 20:19
  • \$\begingroup\$ "Or that wasn't the problem to begin with." to be fair this is a fair comment - the mouse click fault could have been something else entirely, never really considered that \$\endgroup\$ Commented Oct 23 at 20:22
  • \$\begingroup\$ Add: I've just checked the old switch's continuity across the pins and it seems stable, so you're likely right that it could be something else on the board \$\endgroup\$ Commented Oct 23 at 20:28
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    \$\begingroup\$ @gcoulby I have a box of these switches because everyone in my family living here with me -- all my children, their significant others, and all my grandchildren come running to me to "fix my mouse/trackball." It's easy to replace and always "just works right." It isn't complicated to do, so I trust you did it well enough. Which means the issue is elsewhere, I fear. \$\endgroup\$ Commented Oct 23 at 20:38

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There can easily be continuity across the switch and a broken trace to the circuitry. That is my strong suspicion. It is extremely unlikely that an intermittent (“failing”) switch which turns into a reliably not-working switch is not related directly to the switch connections.

Now, a slipped soldering iron tip severing a fine trace or a pre-existing lifted trace near the switch pads could cause this. The infernal black solder mask does not help with troubleshooting but if you tilt the board to get optimal light and use a magnifier or microscope (after cleaning the flux off the board) you should be able to clearly see traces leading from at least 2 of the 3 microswitch connections. Follow them to the next via or pad and check the continuity from the switch pad to there. If it is lacking, add a fine jumper over the trace.

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