Odd Alps Switch in Toshiba T-Series laptops

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Willy4876

26 Apr 2020, 07:53

**edit** I have been informed that the switch is Alps common mount low profile, which is to say nothing new
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I came across a Toshiba T1600 laptop from 1988 in a Value Village a while back. The laptop was completely non-functional due to the system battery leaking onto the PCB. I initially thought that the T1600 would have SKFL like many other Toshiba laptops. And indeed the half height keys on the T1600 board that I have are the compact variant of SKFL, but the alpha block uses completely different switches that I haven't been able to find much info on.
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The Keycaps are reasonably thick Alps compatible Double shots with grey lettering and some have blue lettering on the front which I think is pad printed. Some of the keys like ESC and the arrow keys have white legends.
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Here are the T1600's keycaps compared to some from a Focus FK-2001
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So far I have only seen these switches in some Toshiba T-Series laptops. Specifically the T1600, and T5200. I am not sure of the an actual naming scheme for this switch, so I will refer to it as Alps T-Series in this post.
(general accepted name is Alps common mount low profile)
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Overall the switch looks a lot like a miniaturized version of SKCL/SKCM. The contact assembly consists of a plastic holder which holds metal contact elements that are very similar to SKFL. The top and bottom housings also look similar to SKCL/SKCM, but with a slightly different housing shape, and the addition of a jumper in the bottom housing approximately under where a tactile leaf would have gone in an SKCM switch. Another change to the bottom housing from SKCL/SKCM is that the pip over which the spring sits has been replaced with a slight indent. This has the effect of making reassembly of the switch much more frustrating as the spring easily slides out of the indent. Disassembly of the T-Series is identical to that of SKCL/SKCM. The slider of the switch looks like an SKCL/SKCM slider, but slightly smaller and with a small ramp protrusion which presses on the contact element to activate the switch. There is also a cut out in the slider, similar to SKCL/SKCM, but it goes on the non-contact side of the switch. As far as I can tell the T-Series is only meant to be PCB mount.
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The keyboard unit of the T1600 was manufactured by Alps based on the sticker on the back and the PCB markings. The build quality is nothing to write home about. there is a significant amount of flex, however I do not remember if it was like this in the laptop or if the PCB was supported by the frame. The switches also ping considerably.
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Looking around on the DTwiki for non-SKCM/SKCL Alps switches I initially thought that they might be Alps SKFR, but after reading the article more closely, I realized that SKFR does not use standard Alps mount. Also, Looking more closely at the photos the switches look quite different. The wiki article mentions a taller version of SKFR that does use the standard mount, but the examples that they show do not look like the T-Series.

After looking through the other likely candidates on the wiki I started to look through Alps keyboard related patents from 1985 to 1990. The only patent which I could find that was relevant was this one related to solder penetration of the contacts. This patent does have a switch which looks very similar to the T-Series in the first two photos. There are some minor differences but I am satisfied to say that it is the same switch. In the third and fourth photos it also shows Alps SKFL.

I also was able to find this post from 2012 by Paranoid, which is how I found out that the T5200 has the same switches.

If anybody knows anything else about these switches, especially the name, I would really appreciate it.
Last edited by Willy4876 on 26 Apr 2020, 10:18, edited 2 times in total.

User avatar
//gainsborough
ALPSの日常

26 Apr 2020, 08:18

Isn't that just alps common mount low profile?

wiki/Alps_common_mount_low_profile

edit: sorry if that came off a bit terse >_<
Last edited by //gainsborough on 26 Apr 2020, 08:36, edited 1 time in total.

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mcmaxmcmc

26 Apr 2020, 08:27

Yeah, that should be Alps Common Mount Low Profile, along with some SKFL Compacts on the small keys.

User avatar
Willy4876

26 Apr 2020, 09:59

//gainsborough wrote:
26 Apr 2020, 08:18
Isn't that just alps common mount low profile?

wiki/Alps_common_mount_low_profile

edit: sorry if that came off a bit terse >_<
Yes that is exactly what that looks like. Thank you. Don't worry about being terse I hadn't heard of this switch before and must have just missed it.

TicTocTom

28 Apr 2020, 10:56

Pretty sure my T3200 uses the same switches.

TicTocTom

28 Apr 2020, 11:02

Correction T3100
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