ard at p850ug1.demon.co.uk
Mon Sep 26 18:12:28 CDT 2005
> William> SO that is the original DECwriter then. I do not know if
> William> anyone on the list has an LA30 (they are pretty rare,
> William> apparently), ...
> Probably because they tended to jam a lot. I remember we had one in
> college and scrapped it as soon as we could. All subsequent
> DECwriters were excellent.
That is not the adjective I'd use to describe the LA36 :-)
The LA36 has a really nasty bit of design. There's no home switch for the
carriage. Instead, it rams the carriage into the end stop and detects
that the motor is not turning (no pulses from the position encoder). Fine
until the plastic key moulded into the sprocket breaks. The motor keeps
on turning with the sproket slipping on the spindle and draws enough
current to burn the enamel off the windings. It then goes short-circuit
and blows the motor fuse.
About 10 years ago, this happend at the place where I was studying. DEC
could still supply the motor, but at the ridiculous price of \pounds 130+
(this is a simple permanent-magnet motor). On the ground that research
student's time is not worth that much, a friend and I stripped it down
and rewound it. It ran find for another 2 years.
We finally scrapped that machine. I didn't want it, but I saved most of
the useful bits, including all the PCBs, the printhead, etc. I still have
that motor with the handwritten label 'rewound by ARD and AMG' somewhere.
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