Image Map Image Map
Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: ADM-3A refurb

  1. #1

    Default ADM-3A refurb

    Well, today I became the very proud owner of a working 1980 Lear Seigler ADM-3a. It's going to hopefully be the finishing touch to a homebrew CPU made from LS-TTL. I have a couple of questions, an this forum seems to be generally populated by adults who don't tear strips off people

    1. The keyboard. A few keys stick down. I have been able to release them, and remove the keycaps. From my limited research to date, they are Hi-tek High Profile keyswitches. I will vacuum around all of them, and clean the keycaps. Can I spray electrical contact cleaner on the 2 little arms in the actual switches?

    2. I haven't opened it up yet, that's tomorrow's job when it's bright. Should I re-cap it? As I mentioned it is working, but maybe it would be sensible?

    3. Are there any other preventative measures that anyone might suggest , I'd like this wonderful thing to stay alive for a few more years
    Attached Images Attached Images

  2. #2
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    33,387
    Blog Entries
    18

    Default

    Were it my piece of kit, I'd hold off replacing caps until one failed. "If it works, don't fix it"

    I hated the ADM3A and Hazeltine 1400 terminals. There were better ones out there.

  3. #3

    Default

    Quote Originally Posted by Chuck(G) View Post
    Were it my piece of kit, I'd hold off replacing caps until one failed. "If it works, don't fix it"

    I hated the ADM3A and Hazeltine 1400 terminals. There were better ones out there.
    OK, good advice - thanks. I have sentimental attachment to the ADM-3a, I used one in the late 70s attached to an Apple II running UCSD Pascal.

  4. #4
    Join Date
    Sep 2006
    Location
    Silicon Valley
    Posts
    2,155

    Default

    Quote Originally Posted by Chuck(G) View Post
    I hated the ADM3A and Hazeltine 1400 terminals.
    They both have HiTek keyboards, same as the VT100 and all share the problems with the plungers cracking

  5. #5

    Default

    I got brave and used a pointy-nosed pliers to remove one of the white plungers for a closer look. I can see the cracks in 2 corners. Then, ah, trying to put the damn thing back was nigh on impossible. the 2 metal contacts had sprung together, so I had to use a lock pick, through the plunger and spring to separate them, so the bar in the plunger could go in between them again. Not doing that again, so I am ruling out the idea of widening the waffle slightly with a dremel for each of the keys.

    Does anyone know of any kind of currently available lubricant that would work between the plungers and the walls?

  6. #6
    Join Date
    Apr 2011
    Location
    Brisbane, Australia
    Posts
    489
    Blog Entries
    10

    Default

    I recall a thread on these HiTek broken keys sometime in the last year which I can't locate at the moment but I believe I may be able to repair the cracked corners of the square tube plungers if anyone was willing to post me one or two to me (I'm in Australia) to try, I would post them back (whether repaired successfully or not).

  7. #7
    Join Date
    Jan 2012
    Location
    Connecticut, USA
    Posts
    2,408

    Default

    Chuck, what in particular did you not like about the adm3a terminal? Just curious.

  8. #8
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    33,387
    Blog Entries
    18

    Default

    I didn't like the angle of the screen and the non-detachability of the keyboard. I could live with both, but there were better choices.

    The naked keyboards were available NOS on the surplus market for quite some time during the 1970s. I think I've still got a couple of keys from one that I had.

    I didn't care for the feel, either.

  9. #9
    Join Date
    Jan 2012
    Location
    Connecticut, USA
    Posts
    2,408

    Default

    I could understand that but how many terminals have lost thier accompanying keyboards since they are detacheable?

    I have been on the lookout for a data terminal that prints to paper rather than a crt. Id like at least one of those in my collection.

  10. #10
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    33,387
    Blog Entries
    18

    Default

    There should still be quite a few TI Silent 700s around. That was probably the most popular portable one.

    Some printer makers, such as Diablo and Qume had KSR models of their daisywheel printers.

    And then there's the good old Teletype and the IBM 2741 golf-ball terminal.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •