Porn
Spoiler:
Spoiler:
While the shift keys are pressed (they depress together (along with the lock key to some extent)), pressing the lock key deploys a hook to catch on the mounting frame as you let go of shift:
unlocked:
locked:
Trying to press the lock key without holding shift doesn't really work; the mounting frame is in the way of the hook so you have to push really hard to bend the mounting frame away in order for the key to depress.
Edit 3: After cleaning everything, it is a lot easier to press the lock key and it no longer bends away the mounting frame in the process. There is still some friction but not an unreasonable amount; pressing the lock key on its own may have been intended functionality after all.
It seems they forgot to put an indent in the mold for the lock key part to account for the spring-centering protrusion in the mounting frame; it was instead done by hand:
Spoiler:
no part number on this one
The black slider switches in this keyboard (excluding the shift keys) are 1SW300. Their placings are weird and they are physically identical to the white/red slider switches in this keyboard. They do have different sensors so I will inspect their electrical output later. The one under the 2u key has a much lighter spring than the rest despite having the same part number:
Latching, non-switch and regular illuminated
1SW152 has no sensor, which means that the purpose of this spring is to be so heavy that you don't press the key:
The black slider switches in this keyboard (excluding the shift keys) are 1SW300. Their placings are weird and they are physically identical to the white/red slider switches in this keyboard. They do have different sensors so I will inspect their electrical output later. The one under the 2u key has a much lighter spring than the rest despite having the same part number:
Latching, non-switch and regular illuminated
1SW152 has no sensor, which means that the purpose of this spring is to be so heavy that you don't press the key:
Spoiler:
Spoiler:
Preface: I am not pro electronics man
(regular pulse switch) 86B sensor:
Sink pulse as expected; the output needs a pullup resistor (I used 10k but it probably ended up being more because of the loose connection). Pulse is ~50us. Both output terminals have the same output.
1SW300 8K sensor (the output pin closer to VCC):
Same as 86B
8K sensor (the remaining output pin):
Same as before except it returns to a voltage that is lower than unpressed, staying there until released (~3v vs ~4.5v supply (I am powering it from an Arduino Leonardo))
86B while in the keyboard, with both oscope channels (i.e. showing both output pins at the same time):
As expected
8K while in the keyboard:
Note the one output with persistent evidence of press (lower voltage)
8K while in the keyboard, release event:
Be aware that the channels are swapped here with respect to the press photo (oops). Nothing exciting
(regular pulse switch) 86B sensor:
Sink pulse as expected; the output needs a pullup resistor (I used 10k but it probably ended up being more because of the loose connection). Pulse is ~50us. Both output terminals have the same output.
1SW300 8K sensor (the output pin closer to VCC):
Same as 86B
8K sensor (the remaining output pin):
Same as before except it returns to a voltage that is lower than unpressed, staying there until released (~3v vs ~4.5v supply (I am powering it from an Arduino Leonardo))
86B while in the keyboard, with both oscope channels (i.e. showing both output pins at the same time):
As expected
8K while in the keyboard:
Note the one output with persistent evidence of press (lower voltage)
8K while in the keyboard, release event:
Be aware that the channels are swapped here with respect to the press photo (oops). Nothing exciting
Spoiler:
For a proper writeup with more info check out http://telcontar.net/KBK/Micro_Switch/SW#timed_repeat!
(not my work)
The sensors in the heretofore unseen 1SW300 switches are of K type, which in SD series are known to indicate "timed repeat". Inspecting the sensors left me confused because I did not see any repeating, only a persistent "middle voltage" (~3v) on one of the output pins while the key was pressed. It turns out that the "timed repeat" is generated in the SW-10667 IC; the K-type sensor's sink pulse output on both signal pins followed by the middle voltage partial sink level (?) output of one of the signal pins allows it to simultaneously appear as a regular sink pulse sensor to the encoder and a source level sensor to the SW-10667 (with the help of a PNP transistor).
Edge connector and Timed Repeat logic traced (open image in new tab to see all the pixels):
I called the 8K signal pin "tri-state" but it is not tri-state in the typical sense; I don't know what this is actually called.
The 8K sensors are wired the same as the regular pulse sensors in the usual 2-of-n configuration. The fancy signal pins are each on one of two rows, each of which are connected through a resistor to the base of a PNP transistor. From my understanding (in this configuration), 5v to the base does nothing (i.e. 0v to the SW-10667) whereas the ~3v allows current to flow (i.e. ~3v to the SW-10667). The outputs of the two PNP transistors are connected to the same SW-10667 input, which means that any pressed 8K sensor will have the same result (in the scope of the timed repeat functionality). While its input is high, the SW-10667 outputs a square wave on one pin (wired to one of the SN7404N) and a sawtooth wave (unconnected) on another, each at ~16Hz:
I have yet to figure out the rest of the circuit. I haven't looked at the SN75451BP yet and there is a pin on the encoder with a thick trace that goes straight to edge connector; the encoder may need another power input as it is not even showing any signs of life with my 5v power supply.
- added photo of back of pcb to PCB, ICs, & sensors photos
- added Sensor Signal Investigation spoiler in which I looked at regular pulse switch sensor (86B) and 1SW300 sensor (8K) with oscope both in vitro and in vivo
Edit 2: Progress in solving the 1SW300 Timed Repeat mystery; see new Timed Repeat spoiler
Edit 3: Correction regarding pressing lock key on its own
Edit 4: Excellent writeup on Micro Switch timed repeat functionality by Beardsmore over at http://telcontar.net/KBK/Micro_Switch/SW#timed_repeat
