National Multiplex data cassette tape drive

From: Tom Jennings <>
Date: Thu Sep 2 18:47:11 2004

> >From: "Tom Jennings" <>
> >
> >THe worst part -- the motor had a trimpot in series with it, and that
> >was the sole motor speed control -- and! -- tapes written at one speed
> >adjustment could not be read at another speed!
> >
> >Of course I turned the pot, my fault. But just tapping it was enough. It
> >was total crap.

On Wed, 2004-08-25 at 11:57, Dwight K. Elvey wrote:
> Most of these motors used an internal centrifugal speed
> governor. These were designed to work within some span
> of input voltage. I would guess that the pot was to drop
> the voltage to be within this range. If one was to adjust
> the pot, there should be a range of adjustment that the
> speed ( with load ) was relatively constant. One would
> adjust the pot to be safely within this span.

Not this one. I distinctly recall spending HOURS trying to recover my
tapes, with a 'scope and listening to the data whine on the built-in
speaker. Speed was proportional to the pot setting. Maybe I got an early
one, or something, but it was crap.

The whole package was of poor quality too. I actually threw it out
within a few years.
Received on Thu Sep 02 2004 - 18:47:11 BST

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