IBM PS/2 P70/P75 keyboard (ALPS Plate Springs)
Posted: 02 Apr 2012, 11:54
I'm well aware that this is an older review, originally posted 2011-03-07, but I'm migrating all of my reviews to Deskthority.
So, it's here. Time to review it. As I don't currently have a way of connecting it to a machine, I'm not going to review it in operation until that time. Pics will come later.
Build Quality
Man, this thing feels cheap. It's a lightweight plastic board, with very little metal reinforcement, and PCB mount switches. (The 5576-001 and 002, the other boards that use these switches, are plate mount, FWIW.) A lot of that is due to the need to save weight, however - it's designed to be part of a portable computer. It looks like it's been assembled quite well, however.
The Switches
If you're not familiar with plate spring switches, it's best to start out with the Qwerters Clinic article (Japanese-only, so here's a translation.)
Essentially, here's how it works:
Slider acts on coil spring
Coil spring acts on plate spring that is bowed upward
Plate spring, when pushed down, snaps downward into a plastic piece
Plastic piece pushes two contacts together
Releasing, the tension on the coil spring is reduced, causing the plate spring to snap upwards, freeing the plastic piece, breaking the contacts.
So, the plate spring is a beautifully lightweight (~60g, IIRC) switch with excellent tactile feel, slightly quieter (but higher pitched) than my EnduraPro, yada yada yada.
It has one Achilles' heel, though. (Not as bad as other switches, though.)
It actually starts to feel slightly mushy at speed (tactile events are still sharp when they happen, but the tactile event starts to move around). Wait, what? How can that be?
Simple. Note that the slider never directly acts upon the plate spring - it acts on it THROUGH a coil spring.
Therefore, there's two springs interacting when you're depressing the key.
I'll note that it isn't terrible - the Fujitsu Peerless has a similar problem, but it's far, far worse on the Peerless. Right now, I think I prefer the plate springs to Cherry blues. Think I like beam springs better, though, at this point. (I haven't extensively typed on the plate springs, though. Once I can get it interfaced to a computer, you bet I'll be typing on them a lot.)
Edit: On second thought, it is terrible. Not as terrible as the Peerless, true, but the tactile point moves based on how fast you're typing. That's unacceptable, I'm sorry.
Other impressions
This one, I left out of the switch impressions, because I think it's influenced by the keyboard's construction, but there is a bit of a "typing on cardboard" feel, that others have described out of a Model M2. I have no reason to believe that exists on the plate-mount boards using these switches, though.
The tilt mechanism is kinda clever, although it's huge.
Keycaps look decent quality - I'm guessing they're dye-sub, just like Model M keycaps.
Not sure I have much else to say until I get it working...
So, it's here. Time to review it. As I don't currently have a way of connecting it to a machine, I'm not going to review it in operation until that time. Pics will come later.
Build Quality
Man, this thing feels cheap. It's a lightweight plastic board, with very little metal reinforcement, and PCB mount switches. (The 5576-001 and 002, the other boards that use these switches, are plate mount, FWIW.) A lot of that is due to the need to save weight, however - it's designed to be part of a portable computer. It looks like it's been assembled quite well, however.
The Switches
If you're not familiar with plate spring switches, it's best to start out with the Qwerters Clinic article (Japanese-only, so here's a translation.)
Essentially, here's how it works:
Slider acts on coil spring
Coil spring acts on plate spring that is bowed upward
Plate spring, when pushed down, snaps downward into a plastic piece
Plastic piece pushes two contacts together
Releasing, the tension on the coil spring is reduced, causing the plate spring to snap upwards, freeing the plastic piece, breaking the contacts.
So, the plate spring is a beautifully lightweight (~60g, IIRC) switch with excellent tactile feel, slightly quieter (but higher pitched) than my EnduraPro, yada yada yada.
It has one Achilles' heel, though. (Not as bad as other switches, though.)
It actually starts to feel slightly mushy at speed (tactile events are still sharp when they happen, but the tactile event starts to move around). Wait, what? How can that be?
Simple. Note that the slider never directly acts upon the plate spring - it acts on it THROUGH a coil spring.
Therefore, there's two springs interacting when you're depressing the key.
I'll note that it isn't terrible - the Fujitsu Peerless has a similar problem, but it's far, far worse on the Peerless. Right now, I think I prefer the plate springs to Cherry blues. Think I like beam springs better, though, at this point. (I haven't extensively typed on the plate springs, though. Once I can get it interfaced to a computer, you bet I'll be typing on them a lot.)
Edit: On second thought, it is terrible. Not as terrible as the Peerless, true, but the tactile point moves based on how fast you're typing. That's unacceptable, I'm sorry.
Other impressions
This one, I left out of the switch impressions, because I think it's influenced by the keyboard's construction, but there is a bit of a "typing on cardboard" feel, that others have described out of a Model M2. I have no reason to believe that exists on the plate-mount boards using these switches, though.
The tilt mechanism is kinda clever, although it's huge.
Keycaps look decent quality - I'm guessing they're dye-sub, just like Model M keycaps.
Not sure I have much else to say until I get it working...