13 Mar
2017
13 Mar
'17
1:45 p.m.
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
1. Do you simply pull the keyboard button off the switch or is there a
trick involved?
2. Any other gotcha's?
Thanks,
Marc
13 Mar
13 Mar
2:07 p.m.
Van: Marc Howard via cctech<mailto:cctech at classiccmp.org>
Verzonden: maandag 13 maart 2017 21:45
Aan: General Discussion: On-Topic Posts Only<mailto:cctech at classiccmp.org>
Onderwerp: VT52 keyboard question
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
1. Do you simply pull the keyboard button off the switch or is there a
trick involved?
2. Any other gotcha's?
Thanks,
Marc
My guess is that the VT52, VT55, VT05 and LA30 are identical.
The key fits snug on a plastic white pin, shaped as a ?+?.
Over the plastic pin is a small spring. If the spring is not installed,
the pin will simply ?fall down? due to gravity, causing a continuous
?key pressed? signal.
You can (gently) pull the key cap.
If the pin does not ?fall down?, you have the reason why it is
hard to use: dirt or dust.
Henk, PA8PDP
14 Mar
14 Mar
6:20 a.m.
On Mar 13, 2017, at 5:07 PM, Henk Gooijen via cctalk
<cctalk at classiccmp.org> wrote:
...
My guess is that the VT52, VT55, VT05 and LA30 are identical.
No, fortunately not. The LA30 was notorious for having a very bad and very unreliable
keyboard. Some GT40s had that same keyboard as well, I don't remember if that changed
later. The keycap shapes were different too: larger and more square with sharper
corners.
I don't remember the VT05 well enough, it may have been like the LA30 or different yet
again.
The VT52 keyboard technology shows up in other VT variants of the same family: VT55,
VT61/t, VT62. It is also used in the LA36. Similarly, VT100 style keyboards show up in
other devices of that era: Gigi for example. And the LA120 may use that generation of
switches, I don't remember anymore.
paul
10:11 a.m.
On Tue, Mar 14, 2017 at 7:20 AM, Paul Koning via cctalk
<cctalk at classiccmp.org> wrote:
I know that back in the day, we had about a dozen VT52 and 3 VT50's.
They were the same keyboard, but with different internal circuit
boards (we had a few former VT50's that were upgraded to VT52's, at
least according to the techs that I worked with at the time). I still
remember having to edit my FORTRAN code for a while on a UPPERCASE
ONLY terminal until I got enough seniority to warrant moving up a
dual-case terminal.... thankfully these were all replaced by VT100s
over the years I worked there and my role shifted a bit to needing a
VT100 to support a customer that had an application that used the
advanced features of the VT100: double size characters, line drawing
boxes, etc.
Man, that was a million years ago...
Warner
On Mar 13, 2017, at 5:07 PM, Henk Gooijen via
cctalk <cctalk at classiccmp.org> wrote:
...
My guess is that the VT52, VT55, VT05 and LA30 are identical.
No, fortunately not. The LA30 was notorious for having a very bad and very unreliable
keyboard. Some GT40s had that same keyboard as well, I don't remember if that changed
later. The keycap shapes were different too: larger and more square with sharper corners.
13 Mar
13 Mar
2:12 p.m.
On Mon, Mar 13, 2017 at 4:45 PM, Marc Howard via cctech <
cctech at classiccmp.org> wrote:
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
1. Do you simply pull the keyboard button off the switch or is there a
trick involved?
2. Any other gotcha's?
Thanks,
Marc
Have you tried cleaning, etc? I assume so but I'd be curious if there is a
specific restoration process for the VT50/52. I have not investigated this
myself, but eventually I will need to probably.
Bill
2:52 p.m.
On Mon, Mar 13, 2017 at 4:45 PM, Marc Howard via
cctech <
cctech at classiccmp.org> wrote:
> Hi,
>
> The "2" key on my VT52 is very hard to use. You've gotta pound it and
you
> might get 2 "2"s for your trouble.
I've a similar key on my VT52 -- will be diving in there sometime soon to check it
out, but it might take me a little while to get to it... Will follow-up here when I do
with whatever I find out.
--FritzM.
3:17 p.m.
Mark,
Do you have a picture of what's underneath the key cap? I think those are
Hi-Tek switches underneath. I believe they are similar to the VT-100
keyboard shown here: https://deskthority.net/wiki/DEC_VT100 You can pull
the key cap off as long as you do it straight up.
Find out what kind of key switch it has and we'll go from there.
Santo
On Mon, Mar 13, 2017 at 5:12 PM, william degnan via cctech <
cctech at classiccmp.org> wrote:
On Mon, Mar 13, 2017 at 4:45 PM, Marc Howard via
cctech <
cctech at classiccmp.org> wrote:
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and
you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
1. Do you simply pull the keyboard button off the switch or is there a
trick involved?
2. Any other gotcha's?
Thanks,
Marc
Have you tried cleaning, etc? I assume so but I'd be curious if there is a
specific restoration process for the VT50/52. I have not investigated this
myself, but eventually I will need to probably.
Bill
5:35 p.m.
On Mar 13, 2017, at 4:45 PM, Marc Howard via cctech
<cctech at classiccmp.org> wrote:
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
Sure. It might be cleanable. VT52 keys are crossed wedges, gold plated, with the key
pluger in between which moves out of the way when you push the key. They were incredibly
reliable.
1. Do you simply pull the keyboard button off the
switch or is there a
trick involved?
As I recall, they come right off, just pull up.
paul
11:30 p.m.
On Mon, Mar 13, 2017 at 8:45 PM, Marc Howard via cctech
<cctech at classiccmp.org> wrote:
Hi,
The "2" key on my VT52 is very hard to use. You've gotta pound it and you
might get 2 "2"s for your trouble.
I assume that the keyboard switch is made of unobtanium (If you know of a
substitute chime in) so I'm thinking of swapping it for the "COPY" key
which I guess is useless unless you have the built-in thermal printer.
On the VT52s/VT55 that I've worked on...
It's actually not a separate switch. There's an single moulded frame for
the entire keyboard. Each swtich constists of a pair of contacts which
naturally touch, a return spring and a plunger that keeps the contacts
apart when the key is not pressed.
You can pull off the keycap. Often carefully cleaning the contacts (which
are then visible) will help. The plunger and spring pull out too, officially
you are not supposed to re-use the plunger but you have to now.
The contacts can be desoldered from the track side of the board and
pulled out. There was a special tool to put them back without damaging
them, it is possible (but tricky) to do it with long-nosed pliers. Avoid
removing the contacts unless you really have to replace them with ones
from another key or keyboard.
It's the same type of contact mechanism as in the early TRS-80 Model
1 and the HP85. The technical reference / service manuals for these
2 machines may be of interest.
-tony
2801
days inactive
2802
days old
8 comments
8 participants
participants (8)
-
ard.p850ug1＠gmail.com -
billdegnan＠gmail.com -
cramcram＠gmail.com -
fritzm＠fritzm.org -
henk.gooijen＠hotmail.com -
imp＠bsdimp.com -
paulkoning＠comcast.net -
santo.nucifora＠gmail.com