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This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Rule 1: Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Rule 2: Stay close to the original topic being discussed
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  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Rule 3: Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
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Rule 4: "PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
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Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Rule 5: Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

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If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
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Bringing up a Vector Graphic Mindless Terminal

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    Bringing up a Vector Graphic Mindless Terminal

    (previous thread on my MZ was here - Bringing up a Vector Graphic MZ)

    I finally got my hands on a Vector Mindless Terminal to go with my MZ. Sweet!

    However, the "foam and foil" in the Keytronic keyboard had turned into....foil and "dust that used to be foam". Not so sweet.

    So, I fired up my web browser, took some measurements of the existing parts, popped over to www.mcmaster.com (my favorite industrial supply place), and ordered some self-adhesive plastic, self adhesive foam, aluminized mylar film, and a 7/16" punch:

    IMG_20150815_212720232.jpg

    IMG_20150815_212747215.jpg

    IMG_20150815_234518030.jpg

    IMG_20150816_010606224.jpg

    IMG_20150816_010613346.jpg

    (I'll post the parts list for my fix after I've had a chance to use it for a month or two, there is one aspect of it that I am a little concerned about the durability of. Most of the fixes I could find online involved individually gluing the sandwiches back together - I went with the solution of making an entire new sandwich which I think is a lot less time consuming.)

    #2
    Looks like a good idea - keep us posted!

    Mike

    Comment


      #3
      Resulting parts look very good. The Compaq portable uses these key pads. I made some quick-fix pads a while back but I need to make some better pads like yours.
      My collection: http://tkc8800.com

      Comment


        #4
        I used from mcmaster.com:
        -.007" self adhesive UHMW polyethylene plastic
        -3/16" (0.187") self adhesive polyurethane foam
        -.002" aluminized mylar (aluminized & conductive on one side only, non-conductive on the other side)

        Some notes on each layer, working down the stack:
        -I ended up using 2 layers of the UHMW plastic to make it more stiff, and it still ended up being flimsier than the clear discs used on the original parts. I had to use a plastic pick tool to careful tuck this new plastic under the "grabbers" on each key, at which point it doesn't seem like it is going to come out again.
        -The adhesive between the plastic and the foam is the thing I am worried about. A couple of them started to separate during the "tucking" described above. I'll see if this holds up for a month or two.
        -For the foam, I tried another closed-cell foam that was stiffer, but the impact from the keystrokes dislodged them from the small "grabbers". Conclusion - using open celled foam is important.
        -The adhesive between the foam and the thin aluminized mylar seems perfect. I don't see this coming apart at all. It may have been a better quality adhesive.
        -The aluminized mylar wants to have the *non-conductive* surface facing the pads on the PCB - checked against the original pieces that I removed (makes sense, the switches are capacitive not conductive).

        If I were going to do this again I would get a more rigid plastic similar to the original clear discs (measured .007" with calipers) and glue that to the same type of foam using something like 3M Super 77 adhesive. Then I'd stick the mylar to the self-adhesive foam, wait a bit for the Super 77 adhesive to cure, and punch out the "sandwich" all at once just like I did here.

        I think overall this was a big improvement over the more time consuming methods involving trying to clean up and reuse the original plastic discs and mylar discs.

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