View Single Post
Old 14th Mar 2018, 9:52 am   #6
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: Star Gemini-10 printer

From memory, the printhead-movement on these kind of printers is by a long toothed belt and a stepper-motor. There's also usually some form of absolute-indexing mechanism [a phototransistor/LED assembly) at each end of the printhead-runners to set the end-points and to stop the thing mashing the printhead against the end-stops if you didn't include a carriage-return!

Some similar printers used a slotted optical-disc 'chopper' to sense the printhead-drive's rotation & movement as it proceeds along the rails.

In either case check the optical sensors are clean and free of dust/cat-hair, and also the condition of the belt/stepper-motor: if the stepper's being advanced by the software but the slotted-disc isn't recognising the fact that the carriage should have moved forwards so the next character is to be printed, it can get confused because it hasn't completed the 'print current character' cycle fully, so it prints it again.

If the drive-belt's gone stiff with age, or if the stepper-motor's toothed sprocket has grot in its teeth, this could cause what you're getting too.
G6Tanuki is online now