I would do two things.  Ditch the A/B switch for an electronic switch.
Reversible Bi-Directional AutoSwitch, such as:
http://www.linksys.com/scripts/features.asp?part=DCASR12
If any of the printers are Laser, I would never use a A/B switch.
Keep the TOTAL cable length to any printer less than twenty feet,
or follow the manual for the printers. (This assumes IEEE cables
and printer "super drivers").

I believe the second part of your question dealt with the default printer.
Some windows programs will only print to the default printer, using the
default printer's driver.  Most modern programs will let you select any
printer at printing time.  If you select a printer that is not connected,
but another printer IS there, on the same port, you will "likely" get a
page (or stacks of them) of nothing but control characters and garbage.
             Rick Glazier

>>hello you need to frist go from the back of the computer to the scanner
>>then a cable from the scanner to the switch box i/o and the (a) would to
>>one printer and the b would be the other if you still having problems then
>>go in to the setup and change it to EPP ...hope this helps.....that should
>>fix the problem......
>
>>>        I need some help trying to figure out how to hook up 2 printers and
>>>a scanner on an A/B switch box
>

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