On Sat, Oct 30, 2021 at 11:25 PM Tony Duell <ard.p850...@gmail.com> wrote:
> On Sun, Oct 31, 2021 at 6:15 AM Josh Dersch via cctalk > <cctalk@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 >