seeking info on ASR-33 interface board - test-drb@ccmp.vtda.org

4 Aug 2004

Hi
 One of the things I've seen that is most of these machines seem
to lack lubrication. These things need lots of oil. If you've
no run it for a month or two, you'll most likely need to
quirt some oil in it. The other thing is if they are run
for some time, they need to be cleaned. This means partial
disassembly and dunking in solvent ( a large sonic cleaner system
is best but one of those automotive part cleaning trays with
the pump works well ). There are a lot of moving parts and they
all rub against something.
 Anyway, for the original problem, check the coupling between
the printer unit and the keyboard. The "H" coupling piece
often pops off. This will cause the machine to not lockup
when in the local mode.
 That board is most likely a RS232 interface card. Maybe some
pictures would be good.
Dwight

...
 From: "Brian Knittel"
&lt;brian(a)quarterbyte.com&gt;

Hi Y'all,

I just popped open an ASR-33 I picked up a few weeks ago. The tty ran 
OK in local mode in the store where I found it but in shipment to me 
something happened, it now free runs (runs free?). Maybe it's a loose 
connector.  

In the electronics bay on the right hand side, there's a printed 
circuit board that runs from front to back. It's definitely a power 
supply, and probably also an RS-232 to current loop converter. In 
front is the line/off/local switch, and in back are several large 
Molex connectors. I was surprised to see this printed on the circuit 
board:

MITS INC
TELETYPE INTERFACE BOARD
REVISION 0
COPY RIGHT 1976

Does anybody know if this the Altair MITS? The date seems about 
right.

Was it common to produce custom internals like this for teletypes? 

Anybody have the schematics for this board?  

Thanks,
Brian

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