[SSCH white metal/SKCC grey] Monroe 1405

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zrrion

09 Jan 2021, 05:08

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I have found more and more lately that vintage calculators are a treasure trove of novel and interesting switch designs. Not necessarily good switches mind you, but interesting. This adding machine/calculator is a great example.

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As you can see, there are 2 switches here, one of which is SKCC grey, a variety of SKCC that I have been interested in getting for a while. The other variety is an unnamed switch first described (as far as I know) by snacksthecat in this thread but this is the first I am seeing of this switch actually inside something as opposed to loose.

Now to explain the presence of this one oddball switch I actually have to take a look at the repair bill. Because yes, in addition to the manual this thing came with a product catalogue for the 1400 line as well as an unfilled order form to purchase an extension to the warranty and a bill of repair. Kinda funny that the previous owner didn't get the warranty since they ended up needing it.

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This is a bill for "Repair Keyswitch" which handily explains the SKCC grey here, but why is it SKCC grey instead of the white switch? Well, the 1400 line started in 1975, and the manual is ©1975. The envelope the extended warranty paperwork is in is postmarked Oct. '78, which would mean that the would have happened some time after that as at the time the letter was stamped the warranty was still good (the letter states the warranty will be expiring soon, so it was still in effect in October) which means the repair was likely performed in '79 but depending on when the warranty expired it is possible it was repaired in '78. The earliest I am aware of that SKCC cream has been spotted in anything is in '79, and this switch is not first gen SKCC having a revised design for the bottom housing, so it was likely at least '79 when it was repaired and is within the expected date range for SKCC.
So what is SKCC grey for then? My theory is that SKCC grey is specifically for replacement in anything that uses this white switch, it is plate compatible, PCB compatible, similarly weighted, and has the same travel distance as these white switches while having a shorter travel distance than standard SKCC.

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revised spring peg in the bottom housing, earlier SKCC does not have this little spike
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SKCC grey on the left, SKCC cream on the right. the grey spring is much heavier. I do not have a good way to measure the weight though.
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The recess in the bottom housing had rounded corners instead of square ones, which I have not noticed in any other SKCC switch.
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As you can see the sliders are not the same, the grey has a mount more similar to tall creams than to short creams and the pegs on the bottom shorten the travel to match that of the white switches.

Since the 1400 line started in 1975 it is not guaranteed to have SKCC (and likely, if it does it is due to repair and not a factory setup) and would instead have SKCC's predecessor, hence the white switches.

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9 parts in total, a top housing, bottom housing, slider, brass slider peg, external coil spring, detachable slider top, metal top clip, PCB and contact spring. Kinda overkill I think, and the variants Snacks shows off in his thread are simplified from this design, so I suspect these switches are from closer to '75 and those simplified ones are closer to '78-'79 when SKCC replaced the line.
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love this PCB, and since the switches don't have legs but are rather a PCB perpendicular to the main board they are technically surface mounted. The SKCC switch is able to fit its legs (after some bending) through this PCB hole and is similarly surface mounted to the PCB. Unfortunately the keyboard assembly doesn't have any ALPS branding or an ALPS sticker, so I can't guess what the switch name would be based on the keyboard sticker like you can with other switches. The PCB does have CH34134a but it is a stretch to call them SKCH without ALPS branding. If Snacks would like to suggest a name for these I would defer to that, but without any sources from ALPS and without an obvious cool name "ALPS SKCH" sounds good enough for me.
According to this page these are SCH, and following the convention for 4 letter designations they are SSCH Spring Bridge switches.
Last edited by zrrion on 11 Jan 2021, 17:05, edited 2 times in total.

Rayndalf

09 Jan 2021, 13:20

It's crazy to think people still find new Alps varieties.

I've always loved the look of older desktop calculators, but the really stylish ones usually print to tape... and weigh a ton.

I have a Sharp CS-1122 in a box somewhere. Totally functional, but not quite the pinnacle of industrial design.

Yours must have cost a fortune when it was new. The curves are "space age" but tempered with a slightly boxier overall form and a "tasteful" shade of brown to compliment the wood paneling in your office.

Most people scoff at old junk, but without the scrapes, scuffs and years of sun damage it looks great.

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