After tackling a few of these, I thought I'd write up a small tutorial on how I did it. This is probably old news to many of you, but hope that it might help someone out down the road. With these old Apple mechanical keyboards no longer being made, the more I can keep in circulation the better off things are. Plus, I really like this particular keyboard.
My "victim" in this case is a an Extended II Keyboard. This one has "cream" Alps switches, which I've been told are no longer made and are supposedly damped. It's certainly a bit quieter than many other mechanical keyboards, and also there's a noticeable "cushion" at the end of the keystroke. The "cream" switch keyboards(I've been told) are Made in the USA, and have a small "S" in a block on the lower right corner of the label. These instructions should be generally applicable to any Alps keyswitch Apple keyboard, but make no guarantees beyond the exact configuration I'm illustrating here.
The first thing is to disassemble the keyboard down to the circuit board. I didn't illustrate the process, but on the AEKII it's fairly simple. There is one screw to be removed-it's at the back of the keyboard above the height adjustment slider. Once this is out, the entire top of the case simply pops off. There are two "snaps" at the back of the circuit board that hold it in place-these are pulled out, the circuit board lifted out, and pulled away from the tabs at the front that secure it. Just watch the two ADB ports, which lift out, but are attached to the circuit board by fairly heavy duty ribbon cable.s
With that assembled, I started by assembling all the tools I needed for the job. The basics are(as illustrated below)
1. A soldering iron(preferably a lower-powered one)
2. Some sort of desoldering tool(I use a braid-you may have your own preference)
3. A VOM in some form or fashion
4. Solder
5. I found a pocket knife enormously useful, although this is probably optional.
Also not pictured is 2000 grit sandpaper.
With the circuit board free, your first challenge will be locating the appropriate solder points for the key switch that's giving you trouble. Each switch has only two solder points. The switch is open when not pressed, but closed when pressed. Looking at the bottom of the keyboard will show that each pair of solder points is numbered, but unfortunately these don't generally mean a whole lot
. I found it easiest to eyeball the location as best as I could, then use the VOM to test for continuity at the contacts while pressing the keys. Unfortunately, this isn't infallible, as a failing keyswitch will often register a high resistance or even infinite resistance on a single press. Repeated firm presses will usually get the needle to peg-or a beep if you are using a digital VOM with a continuity function.
Once the correct contact is located, the next step is to desolder the switch from it. I've tried several desoldering tools, and have settled on the braid as the best option for me. Basically, this is a tightly woven mesh of copper wire that is placed over the joint and then heated with the iron/gun. As this is done, the solder is drawn into the braid through capillary action. The braid has a limited capacity, and will need to be periodically trimmed and discarded. Even so, I've found that-overall-it gets the joints cleanest. When using a braid, just remember that copper is an excellent heat conductor and will get very hot, so don't attempt to hold the braid directly in your hands(I put this reminder in for myself as much as others).
It takes a few minutes of work, but eventually the switch contacts will be free.
At this point, you can use a couple of different approaches. I found it easiest to leave the key cap on the switch for additional leverage, and carefully "rock" it out of the keyboard. You may need to go back a time or two with the desoldering tool and remove more solder. Alternatively, solder is soft enough that it can be cut with a good knife, and I will sometimes use my pocket knife to help me get the switch free.
Once out, the switch(with key cap attached) will look like this
And the keyboard where the switch was removed like this
The keycap can easily be popped off to leave this
From this point, the switch can be disassembled. This is done by carefully prying the tabs on the "top" and "bottom" side outward, and simply pulling the switch apart. I'll add a caution at this point that the two solder tabs on the bottom need to slide through fairly narrow openings in the bottom of the keyswitch. If they excess solder build-up, they will not go. Thus, they may need some additional attention with the desoldering tool.
The fully disassembled keyswitch looks like this
The large plastic piece at the bottom is the armature which the keycap presses, and the spring provides resistance. The "springy" metal piece has two fingers on it. Not shown-on the other side of the part with the solder tabs-are two corresponding fingers.
With the switch apart, I do a couple of things. First, I very lightly polish all four of the contacts with 2000 grit sandpaper. I then carefully bend then slightly outward from the base(using a knife blade for backing). This whole process really is not very involved, and takes me just a couple of minutes once the switch is apart.
I reassemble all the parts in the top of the switch(there's really only one way for them to go in)
And then snap the bottom back on-making sure the two solder tabs pass through their corresponding holes in switch bottom(it won't go back together if this is not done).
I then use the VOM-again-across the poles of the switch to confirm that it goes from infinite resistance to no resistance every time the switch is pressed. On an analog meter, the needle should peg every time, and a digital meter should beep every time. If not, take the switch apart and try again.
I then set the switch back down on the keyboard
Solder it back in place
And replace the cap.
If there are other switches in need of attention, go ahead and do those in the same manner. If not, put the keyboard back together and get back to typing!
Overall, I'd estimate that the process takes me 20-25 minutes per switch. The bulk of the time is spent unsoldering and removing the switch(10-15 minutes). Actually rebuilding the switch takes less than 5 minutes, and reattaching it even less than that.
My "victim" in this case is a an Extended II Keyboard. This one has "cream" Alps switches, which I've been told are no longer made and are supposedly damped. It's certainly a bit quieter than many other mechanical keyboards, and also there's a noticeable "cushion" at the end of the keystroke. The "cream" switch keyboards(I've been told) are Made in the USA, and have a small "S" in a block on the lower right corner of the label. These instructions should be generally applicable to any Alps keyswitch Apple keyboard, but make no guarantees beyond the exact configuration I'm illustrating here.
The first thing is to disassemble the keyboard down to the circuit board. I didn't illustrate the process, but on the AEKII it's fairly simple. There is one screw to be removed-it's at the back of the keyboard above the height adjustment slider. Once this is out, the entire top of the case simply pops off. There are two "snaps" at the back of the circuit board that hold it in place-these are pulled out, the circuit board lifted out, and pulled away from the tabs at the front that secure it. Just watch the two ADB ports, which lift out, but are attached to the circuit board by fairly heavy duty ribbon cable.s
With that assembled, I started by assembling all the tools I needed for the job. The basics are(as illustrated below)
1. A soldering iron(preferably a lower-powered one)
2. Some sort of desoldering tool(I use a braid-you may have your own preference)
3. A VOM in some form or fashion
4. Solder
5. I found a pocket knife enormously useful, although this is probably optional.
Also not pictured is 2000 grit sandpaper.
With the circuit board free, your first challenge will be locating the appropriate solder points for the key switch that's giving you trouble. Each switch has only two solder points. The switch is open when not pressed, but closed when pressed. Looking at the bottom of the keyboard will show that each pair of solder points is numbered, but unfortunately these don't generally mean a whole lot
. I found it easiest to eyeball the location as best as I could, then use the VOM to test for continuity at the contacts while pressing the keys. Unfortunately, this isn't infallible, as a failing keyswitch will often register a high resistance or even infinite resistance on a single press. Repeated firm presses will usually get the needle to peg-or a beep if you are using a digital VOM with a continuity function. Once the correct contact is located, the next step is to desolder the switch from it. I've tried several desoldering tools, and have settled on the braid as the best option for me. Basically, this is a tightly woven mesh of copper wire that is placed over the joint and then heated with the iron/gun. As this is done, the solder is drawn into the braid through capillary action. The braid has a limited capacity, and will need to be periodically trimmed and discarded. Even so, I've found that-overall-it gets the joints cleanest. When using a braid, just remember that copper is an excellent heat conductor and will get very hot, so don't attempt to hold the braid directly in your hands(I put this reminder in for myself as much as others).
It takes a few minutes of work, but eventually the switch contacts will be free.
At this point, you can use a couple of different approaches. I found it easiest to leave the key cap on the switch for additional leverage, and carefully "rock" it out of the keyboard. You may need to go back a time or two with the desoldering tool and remove more solder. Alternatively, solder is soft enough that it can be cut with a good knife, and I will sometimes use my pocket knife to help me get the switch free.
Once out, the switch(with key cap attached) will look like this
And the keyboard where the switch was removed like this
The keycap can easily be popped off to leave this
From this point, the switch can be disassembled. This is done by carefully prying the tabs on the "top" and "bottom" side outward, and simply pulling the switch apart. I'll add a caution at this point that the two solder tabs on the bottom need to slide through fairly narrow openings in the bottom of the keyswitch. If they excess solder build-up, they will not go. Thus, they may need some additional attention with the desoldering tool.
The fully disassembled keyswitch looks like this
The large plastic piece at the bottom is the armature which the keycap presses, and the spring provides resistance. The "springy" metal piece has two fingers on it. Not shown-on the other side of the part with the solder tabs-are two corresponding fingers.
With the switch apart, I do a couple of things. First, I very lightly polish all four of the contacts with 2000 grit sandpaper. I then carefully bend then slightly outward from the base(using a knife blade for backing). This whole process really is not very involved, and takes me just a couple of minutes once the switch is apart.
I reassemble all the parts in the top of the switch(there's really only one way for them to go in)
And then snap the bottom back on-making sure the two solder tabs pass through their corresponding holes in switch bottom(it won't go back together if this is not done).
I then use the VOM-again-across the poles of the switch to confirm that it goes from infinite resistance to no resistance every time the switch is pressed. On an analog meter, the needle should peg every time, and a digital meter should beep every time. If not, take the switch apart and try again.
I then set the switch back down on the keyboard
Solder it back in place
And replace the cap.
If there are other switches in need of attention, go ahead and do those in the same manner. If not, put the keyboard back together and get back to typing!
Overall, I'd estimate that the process takes me 20-25 minutes per switch. The bulk of the time is spent unsoldering and removing the switch(10-15 minutes). Actually rebuilding the switch takes less than 5 minutes, and reattaching it even less than that.