Maintenance/Mouse button replacement: Difference between revisions

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[[File:Scattered screws.jpg|thumb|So many screws]]

Time to go deep. Take the everything apart and find out what's going on. I'd rather not pull the switches back off, for fear of tearing out the remaining traces. Instead, there's got to be a way of reconnecting the signals that connected to the missing surface-mount pads. A continuity tester confirms that the working buttons do what we might expect: one side has a positive voltage and the other causes a wire in the board connector jumper to toggle between high-impedance and the positive voltage. The broken buttons don't cause a similar signal anywhere on the jumper, and it's hard to tell where the traces should have gone because of the high-obscurity board layout and black solder mask.

[[File:Mouse confidential board.jpg|thumb]]

Oh hold everything: the trivial middle board is clearly marked "confidential"! We can't go on... joking.

[[File:Two layer board.jpg|thumb|Two-layer board edge]]

This is only a two-layer board so everything is on the front and back, networks can only go through the board via a via through-hole, sideways on a trace or plane of foil, or through a component. Nonetheless, I can't quite follow the signal. Now we're going to have fun: I make a jumper ending with a small resistor and clip it to the positive voltage of a working switch, poke this into each wire of the board connector one at a time with the mouse turned on, and watch xev.

Luckily for me, this is successful! It becomes clear which of the switch pads should carry positive voltage and which board connector wires relay the outgoing button signals.

[[File:Mouse final jumpered top.jpg|thumb|Top jumper]]

In the end it only takes two additional wires to make the mouse fully functional. I would put this hack firmly on the "I'll jam the satellite uplink with my hair clip" scale of electrical engineering, and the result is a fire hazard which I wouldn't feel comfortable letting anyone else use. But it's good enough for me. The top jumper looks especially scary since it attaches to an unusual hole cut in a ribbon cable, but both wires make me slightly queasy.

[[File:Mouse final jumpered back.jpg|thumb|Bottom jumper]]

== Notes ==

@@ Line 47: / Line 47: @@
 [[File:Scattered screws.jpg|thumb|So many screws]]
 Time to go deep.  Take the everything apart and find out what's going on.  I'd rather not pull the switches back off, for fear of tearing out the remaining traces.  Instead, there's got to be a way of reconnecting the signals that connected to the missing surface-mount pads.  A continuity tester confirms that the working buttons do what we might expect: one side has a positive voltage and the other causes a wire in the board connector jumper to toggle between high-impedance and the positive voltage.  The broken buttons don't cause a similar signal anywhere on the jumper, and it's hard to tell where the traces should have gone because of the high-obscurity board layout and black solder mask.
+[[File:Mouse confidential board.jpg|thumb]]
+Oh hold everything: the trivial middle board is clearly marked "confidential"!  We can't go on... joking.
+[[File:Two layer board.jpg|thumb|Two-layer board edge]]
+This is only a two-layer board so everything is on the front and back, networks can only go through the board via a via through-hole, sideways on a trace or plane of foil, or through a component.  Nonetheless, I can't quite follow the signal.  Now we're going to have fun: I make a jumper ending with a small resistor and clip it to the positive voltage of a working switch, poke this into each wire of the board connector one at a time with the mouse turned on, and watch xev.
+Luckily for me, this is successful!  It becomes clear which of the switch pads should carry positive voltage and which board connector wires relay the outgoing button signals.
+[[File:Mouse final jumpered top.jpg|thumb|Top jumper]]
+In the end it only takes two additional wires to make the mouse fully functional.  I would put this hack firmly on the "I'll jam the satellite uplink with my hair clip" scale of electrical engineering, and the result is a fire hazard which I wouldn't feel comfortable letting anyone else use.  But it's good enough for me.  The top jumper looks especially scary since it attaches to an unusual hole cut in a ribbon cable, but both wires make me slightly queasy.
+[[File:Mouse final jumpered back.jpg|thumb|Bottom jumper]]
 == Notes ==