[GreenKeys] Need ASR33 repair help, in Ann Arbor MI

[drlegendre .]

Hi Keith,

I don't know the first thing about 33 ASR mechanicals, but I have been
doing a bit of study on the interfacing. Getting it to talk to a modern PC
is actually very straightforward, and you can either take the DIY or
commercial route. In short, you simply need a current loop -to- RS-232
converter.

There are presently several suitable devices on eBay selling (and not
selling) in the $30 range. The less expensive adapters are typically of the
'passive' type, so you will have to add a basic 12V wall-wart to actually
supply the current for the 20mA loop. Note that the '33' interface is also
of the passive type - again, it does not supply the loop current, thus you
need an 'active' adapter; adding the wall-wart transforms the adapter to an
'active' interface.

The DIY route is also fairly simple, requiring only a dedicated RS-232 -to-
TTL converter IC like the MAX232, a couple of common optocouplers, and some
standard passive components (resistors, caps). Once again, you will need a
12V supply to power the device and supply the loop current. I happen to
have several MAX232 chips on-order, and would be happy to send one or two
your way once they arrive. The optocouplers can be just about anything, so
long as they will handle 20mA - at 110 baud, you really don't worry too
much about the opto switching / transition speeds..

Hope that helps!

On Thu, Nov 27, 2014 at 12:09 AM, <acti at provide.net> wrote:

> A while back, there was someone on this list living
> -near- Ann Arbor MI, that knows a lot about the
> ASR33 TTY mechanics (IIRC maybe in Whitmore Lake?)...
> I can't find your name and contact data.
>
> If you are still here, can you please contact me off-list?
>
> I need some local help to get my ASR33 running
> again soon, so I can punch some paper tapes.
> (...I'll also need to discuss updating its
> interface, so I can talk to it with a PC XP laptop ! :-)
>
> It developed some sort of mechanical problem during
> its last move years ago (I think from mini-trailer
> vibration), and I didn't have time then to figure
> out what happened to it.  I need to find someone
> that knows ASR33 mechanics, that can help me
> diagnose exactly what went wrong with it.
>
> It has also been sitting in a (heated) basement
> for quite a while since then, so I may also
> need some help/advice on a cleaning / relube job.
>
> Can any Teletype experts living near Ann Arbor MI
> please contact me, and help me evaluate what
> I need to do to get it up and running again?
>
> Thanks!
> - Keith Mc., in Ann Arbor MI
>
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