DEC LA180 printer

Harten harten at
Mon Feb 4 14:50:09 CST 2008

In message <200802011819.m11IJ3ch015535 at> you wrote:

> At 09:37 AM 2/1/2008, Dave McGuire wrote:
> >On Feb 1, 2008, at 6:35 AM, Rick Murphy wrote:
> >>>My books are still in storage,( basement wall are up! ), but I
> >>>seem to
> >>>recall the LA36 had adjustments on the servo. Could the LA180?
> >>
> >>Yes, it's basically the same mechanism.
> >>I've sent the maintenance manual to der Mouse for scanning.
> >
> >   LA36 and LA180 are the same mechanism?  Are you sure?  I don't
> >recall much similarity there, especially in terms of speed.
> That's what I meant by "basically". :-) It's quite similar. 
> Unidirectional, belt-driven. Motor has a sensor disc on the back for 
> position pickup. I doubt there's any parts that are interchangable, 
> though, so you're correct.
>          -Rick

I just managed to fix the problem with the init-sequence.
There was a faulty IC "9601PC" by which the controller senses that the
servo-motor isn't able to turn (paper jam).
The LA180 has the same sensors on the back of its servo-motor as the LA36
to count the dot colums and to determine the direction of carriage movement.
It took me one hour to adjust the sensors mechanical and electrical (and i have
a oscilloscope to watch the signals against each other).

Now on power-up the carriage moves slowly to the left side where it stucks for
a short while and then moves a litte (a few mm) right - no error bell!

On setting the selftest switch to the ON position (paper loaded) an putting the
machine ON-LINE, the paper ist continiously feeded but no character is printed.

Any idea?

Axel Harten.

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