20 Jun
1999
20 Jun
'99
8:49 a.m.
At 12:59 PM 6/20/99 +0100, Tony wrote:
There is a problem in shipping Model 33s if the seller
is not clued-up.
The 'typing unit' is not fixed down - it rests on rubber mounts, and is
sort-of held in by the H-plate.
Not to worry, the shipper was very clued and installed the shipping lock.
I'm going to reproduce it a local machine shop before returning it so that
I can have one "on hand."
Do you have the Teletype manuals? If you have a
partsbook, it's probably
easiest if you give me the part numbers of the bits you're talking about
and I'll look them up.
Yes I do, lets see... Hmm, I can't seem to find it in the exploded view of
the typer or the reader.
Problem #2:
Typing prints characters, however the print head does not
advance after something has been typed (mechanical pawl somewhere gone
missing no doubt).
Look at the 'spacing area' (front left of the typing unit, just behind
the keyboard). There's a toothed belt that moves the carriage. The left
sprocket has a ratchet wheel on the bottom with pawls to step it along
and allow it to return. Either it's got stuck in carriage-return mode (can
you move the carriage
_freely_ by hand and will it spring back, or is the ratchet engaged), or
the space-inhibit link (used to cause it not to move on control
characters) is active.
Ok, found the general area in 33 Typing Unit Adjustments volume, I'm
looking at the spacing ratchet on page 75. My unit looks somewhat different
than the picture :-(
I can see the spacing ratchet and the feed pawl would should presumably
engage it, only the feed pawl does not engage. (the ratchet however _is_
locked so the carriage return is not active).
I can also see what appears to be a bit of insulator diagonally in the unit
here that "looks" out of place but is pretty tightly wedged in there. Its
possible that before the first <CR> hit this was lying in there and when
the carraige returned it "caught" this bit of floatsam.
I need to disengage the spacing ratchet so that I can move the carraige
back to the middle to see if that helps. Ideas on how to do this? Page numbers?
OK, the reader control is quite simple (I am assuming
you have a manual
reader control unit - 3 position lever 'switch' on top of the reader -
not an automatic one (4 positions, and has contacts on the typing unit
for Xon/Xoff).
Yup, manual reader.
The reader run circuit is quite simple. The switch on
the reader,
together with the end-of-tape trip on the reader control the magnet at
the rear right that we've been going on about already. Turning on the
reader energises that magnet and releases the trip link. That link then
engages the Tx clutch. Every revolution of the Tx shaft, the link is
moved forwards. It then trips the leaf contact on top of the typing unit,
which causes the reader magnet (under the reader) to step the tape on. If
the trip magnet has been de-energised, then the link will latch in the
forward position, keeping the reader magnet de-energised and stopping the
Tx shaft.
Ok, got all of that.
Obvious checks are : Is the trip magnet being
de-energised (reader
control contacts opening?). Is the magnet mechanically sticking? Is the
trip link moving forwards far enough to latch in the idle postion?
I'm guessing it is the last, it isn't moving forward enough to latch into
the idle position. I can manually push it back into the leaf spring and
start it up :-). But if I catch it and pull it forward it stops. I suppose
I can try manually de-energizing the magnet by unplugging it as well.
Oh, taking ASR33s to bits is fun....
If you say so, I have on it bits in my garage (well most bits) and the one
in my garage has the "automatic" reader which I might like to rescue and
retro fit into one. But at the moment the keyboard isn't happening. (it had
one of the "pins" along the side of the plastic broken off (remember, this
is the one that took the fall) and that makes the cover not attach firmly.
--Chuck