Teleprint 390

[Tony Duell]

> 
> Hi,
> 
> > Is the 'call control unit' -- the electronics chassis on the right hand 
> > side -- the same?
> On *my* 390 there is a slightly different "call control unit". But I 
> have several 33s and nearly each has a different ccu. Normally you don't 

There is one Teletype call control unit that was used in the version that 
had a built-in 20mA loop interface and no modem. This is the version 
that was supposed to be directly connected to the computer's interface, 
and it's the version most commonly found.


> have to worry about that if you have a current loop device in working 
> condition. There are also a lot of different wiring options for the 

No, but it certainly matters if you have to repair it...

> machine.....
> 
> > where the mechaical bits are normal Teletype ones, but the 
> > call control unit is very different. It's built on a couple of PCBs (!) 
> > and can handle both RS232 and current loop interfaces.
> Hey, that's cool. PCBs are normal in all CCUs.

The Teletype one I menitoned has one little PCB in the selector magnet 
driver (the reader PSU, also on a PCB, is not strictly part of the CCU, 
even). There's a lot of hard-wiring too.

The Data Dynamics one, IIRC, has 3 PCBs in it. One carries all the Molex 
connectors at the back, which the mechanical parts plug into. The others 
contain the reader PSU, singalling PSU, selector magnet driver, etc. 
Almost no components no on the PSU.

> It will be hard to find schmematics for that.

Yes, but probably not too hard to trace out by hand if need be.

> 
> > Believe it or not, the Teletype manuals for the Model 33 do have cleaning 
> > and lubrication charts for the cover...
> :-)
> ... but there's no information about glueing together broken pieces of 
> grey plastic....  :-)

The best way to do this IMHO is to put the bits together and run a brush 
dipped in dichloromethane along the cracks. This will disolve the plastic 
and weld the parts together. Now take some cotton fabric, put it over the 
repair on the inside of the case, and brush it over with the 
dichloromethane. When the plastic has softened, force the fabric into it. 
The result is a fairly strong repair...

-tony