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Fixing an inoperative key on a Model 1 keyboard, ALPS

Biff

Member
Joined
Jul 13, 2017
Messages
43
Location
NE Ohio
Hi,
I'm in the process of trying to repair a Model 1 with a video problem, and while typing in the video test program in Sam's Computer Facts for the Model 1, I also discovered my 'A' key isn't working.
It's the only key on the entire keyboard that doesn't work, so it's not a broken trace issue.

I verified with my meter that there is no continuity between the key switch pins when the 'A' key is depressed.

I've repaired a Model 4 keyboard ages ago that just needed the switches opened and the contacts re-carboned.
I'm hoping that this all it will take to fix this key switch.

My question is - how do you open the key switch? Can you do so w/out having to remove it from the PCB - does the top lift off like on my Model 4?

I see there are two snaps on either side of the switch - do you simply squeeze them and pull on the stem?
I haven't tried yet - since I didn't want to bust it - so I thought I'd check here first.

thanks

Jim

alps_keystem.jpg
 
That looks like the same key switch as on my early Model III.

I've documented the process of how I cleaned my switches at: https://gonk23.wordpress.com/trs-80/keyboard-repair/

But basically you need to de-solder the terminals and then squeeze the 2 snaps in to pull it out. The tricky part is not breaking the top/bottom plastic lip of the switch when you remove it. Once the switch is out you can you take it apart further and clean the terminals with alcohol.
 
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