ISO: GE Terminet 300 knowledge

[Josh Dersch]

On Sat, Oct 30, 2021 at 11:25 PM Tony Duell <ard.p850ug1 at gmail.com> wrote:

> On Sun, Oct 31, 2021 at 6:15 AM Josh Dersch via cctalk
> <cctalk at classiccmp.org> wrote:
> >
> > Hey all --
> >
> > I picked up a GE Terminet 300 which appears to be mostly functional, but
> is
> > in need of alignment --  it's printing fairly smudged garbage with a few
> > recognizable characters intermixed.  Character positioning (horizontal)
> > seems to be fairly irregular, for the characters that print clearly.
> >
> > The unit has suffered some knocks in its life and it's clear the
> photocell
> > board has come slightly loose, which I'm sure is not unrelated, so I'm
> > studying the service docs to get a better idea what's going on.  There's
> an
> > alignment gauge which I could reproduce if I had any idea what it's specs
> > are.  The service docs are a bit vague and the photocell assembly is a
> bit
> > difficult to see, buried beneath the print band on the left hand side.
> >
> > Anyone out there have any experience with these?  Any wisdom to impart
> here?
>
> I think this was badged 'ICL' in the UK, I have a couple (118
> characters/line KSR and 75 charaters/line RO) but it's been several
> years since I worked on them.
>
> From what I remember the photocell unit is the main timing sensor. It
> detects the bottom tabs of the print fingers, the start finger of each
> set has a wider tab spot-welded to it (and thus that finger can't be
> removed from the belt) which gives a wider pulse that's detected by
> the electronics.
>

Yes, this matches what the service docs explain, sounds like the same
machine.


>
> If the photocell unit is not in the right position laterally but still
> gives good timing pulses, the thing will work but won't hit the
> fingers cleanly. You should still get the right characters, or perhaps
> the one before or after on the belt if it's way out of position. But
> if it's not producing clean pulses all the time then the thing may
> print random characters.
>
> A missing finger is bad news for that reason, The missing timing pulse
> may well confuse the electronics.
>

I should have been more clear -- only the top of the finger is missing, the
bottom is still present, so it should in theory be generating proper pulses.

I should see if I can pull the assembly out and clean it, I suppose if the
optical sensors are dirty it'd be a problem.

- Josh


>
> -tony
>
>
>
> >
> > Also, anyone have any spare print fingers?  My print band's missing one
> (a
> > "9") and I suppose it wouldn't be a terrible idea to have a few extras
> just
> > in case...
> >
> > Thanks,
> > - Josh
>