Help needed on a DEC LA180 printer

tiggerlasv at aim.com tiggerlasv at aim.com
Wed Jan 30 22:38:46 CST 2008


I'm assuming you've already verified that the carriage isn't binding, 
by trying
to move the print head with the printer turned off, so we'll skip that 
step.

If the carriage is moving, and suddenly stops, with a continuous error 
bell,
it's possible that there is something wrong with the head positioning 
electronics.

The motor that moves the print head has an encoder wheel on the back of 
it,
which of course is monitored by the logic board.

I would GUESS that if the printer doesn't see any feedback from the 
encoder,
that it would stop the print head, and turn on the warning bell.

I have one of these at home, with the classic "head slam" problem,
which is also related to the encoder and/or electronics.   It will 
print,
but when returning to the left-hand side, it will start with a gentle 
tap while it's printing,
then a bit louder, then a bit louder, as the carriage slams harder and 
harder
up against the left stop plate.  Finally, it stops, and the bell sounds.

In this instance, it's losing track of where the print head is.
I haven't had time to isolate the problem myself, but it sounds like
you're having problems along the same lines.

I would check the connections to the encoder wheel. . . the encoder 
wheel itself,
(sometimes they get dust / dirt inside the enclosure, which interferes 
with operation),
then the infrared sensors, and related circuitry on the board.




Tim






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