[GreenKeys] Model 33 ribbon advance constantly on

[Ethan Blanton]

Troy Peterson via GreenKeys wrote:
> I've finished completely cleaning and re-oiling my model 33 ASR, and 
> after checking everything over as best as I could I decided it was time 
> to get things moving again so I've put the motor back in and put the 
> belt on. Here's a short video of it:
> https://youtube.com/shorts/dcXCMkHSOyU

That is normal behavior for "running open" or "spacing".

> This is just the printer section motor running directly from AC off of a 
> variac. It's only running at around 90v and drawing between 1 and 1.5 
> amp.  One thing that seems odd to me is the ribbon ratchet seems to 
> continuously feed forward. Is this normal?  The hammer is moving, but 
> not actually striking the printhead and I believe that to be normal in 
> this state but it seems strange that the ribbon would always spool when 
> it's not printing...  Does the ribbon always continue to feed (and 
> autoreverse) on these machines when it's running?

I believe that is normal.  Because there is no current on the loop, it
is continuously "receiving" a start bit, followed by eight zero bits,
as far as it knows.  It is therefore "printing" a NUL byte, which does
suppress the hammer blow, but is otherwise orienting the print
head/etc., as if it were printing a character.  Every time it prints,
it advances the ribbon a bit.

You should be able to stop the spacing by providing current for the
current loop.  I don't know about the 33, but for my 35 ASR, a pair of
AA batteries and a 150 ohm resistor drove the current loop just fine
and locked in the magnet; however, the 35 has an internal regenerator
and I do not know about the 33.

Ethan