ISO: GE Terminet 300 knowledge

[Tony Duell]

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.

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.

-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