Canon V-20 Dead Keys

Resident (49)

14-02-2021, 02:27

Hello! I recently got a Canon V-20 MSX1 and for the most part it's working perfectly. However, a few keys- "N", "K", "9", ",", and "F5"- aren't responding. The cursor keys also need a lot of pressure to work but I'm not sure if that's just how these machines are. I popped it open and tried cleaning the key switches with compressed air but that didn't make a difference. "N" and "," are a little "squishy" feeling but with the other keys you wouldn't be able to tell by feeling that anything is different. Looking at the underside of the keyboard PCB, I didn't see anything different between the keys that did and didn't work. I tried to use a multimeter to see how the dead keys behaved differently but on both the good and bad keys the top and bottom rows of pins have continuity whether or not the key is depressed, so I think I'm checking in the wrong places. I have a Japanese model but the European manual says the key switches are part number SK0111X12A, but it doesn't seem that replacements are made anywhere. Has anyone encountered this before and have any advice on how to proceed? Thank you!

Por NetNomad

Resident (49)

15-02-2021, 01:57

Made some headway on this. I cracked open one of the keyswitches and on the inside it's a piece of plastic (the white circle you see in the above picture) on top of a rubber plunger that presses down on two copper-looking pads. If you take a jumper wire and press each end on each pad, it'll trigger a key press. Putting F5 back together was enough to get it working perfectly, but the other keys only work when poked with a jumper. Taking the rubber plunger thing out of F5 and putting it into other keys didn't seem to make a difference so the issue I'm guessing is with the pads themselves. As a backup plan I guess I could wire up a regular 'ol push button between the two pads, but I'd like to get the regular keys working if possible first. Two of them look like they have some oxidation going on but the other two as best I can tell look clean. Any advice?

Por sdsnatcher73

Prophet (3849)

15-02-2021, 07:46

I think the way to go is disassemble the whole keyboard and give it a thorough cleaning. You can check some videos on YouTube or leave it to someone who has experience (I would do the latter but I have two left hands and feet )

Por NetNomad

Resident (49)

18-02-2021, 01:52

Thank you, that was a good idea! I watched a few videos and it turns out that the Sony HB-75 and the Toshiba HX-10 have the same keyswitch mechanism. Cleaning like they do in the videos got most of the keys working except for "n" and ",", and then i tried swapping the plungers and it turns out those two plungers are bad. So I found this article and now I've got "keypad fix" paint coming in the mail and i'll report back if that did the trick.

I'm embarrassed by how cleanly they got the tops of the keyswitches off in the videos while I went a bit medieval with pliers...