Your average manual AB switch box uses a make before break switch.  In other
words, it momentarily shorts pins together before breaking the connection as
you flip the switch.  Over time, these momentary shorts can burn out the port
on the printer.  Electronic auto switching boxes don't have this problem.  Back
in the olden days of the Laserjet I and II, I remember being told HP would void
the warranty of a printer hooked to a manual box, but had no problem with the
electronic ones.

David Grossman wrote:

> I'd like to hear more comments about HP's argument that an A/B switch box
> will damage a computer. I have not found that to be the case with many
> printers that I have set up. What is their reasoning?
>
> Granted, there may be a problem with the printer recognizing the driver if
> it isn't switched to the printer before loading Windows. And it's also true
> that it you accidentally send a document with a different printer setup
> you'll get a lot of gibberish. You'll waste paper and ink. However, I don't
> see how you will damage the printer by doing so.
>
> the At 13:48 27/01/99 -0500, you wrote:
> >Posted on behalf of Susan Hays ([log in to unmask]),
> >         by moderator, Elizabeth Boston
> >
> >
> >
> >Be patient this is my first time to do this.  I have an
> >Office Jet 520 and a HP 722C printer.  I was told the only
> >way I could use my
> >722C as my primary printer was to add another parallel port
> >to my computer.
> >Otherwise the Office Jet 520 would take over as the printer,
> >no matter what.  I
> >was also told that an A/B switch would damage the HP722C
> >printer and HP would
> >not hold up their warranty if an A/B switch was used.
> >         Does anyone have any other solutions besides adding
> >another parallel port?  Is there an easier way?  In the
> >meantime, is there any way I can use my Office Jet 520 as a
> >fax machine?  Sure could use some expert help.
> >
> >Thank you,
> >Susan S. Hays
> >
> >            Do you want to signoff PCBUILD or just change to
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> >
>
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