Keyboard Problems - North Star DIMENSION Service Manual

TROUBLESHOOTING
Keyboard Problems
Symptom Explanation
Solution
Incorrect
(The solution 1.
characters
applies only
appear on the
to 2.
screen .
monochrome
workstation
boards.)
3.
Sometimes the The
Caps Lock workstation
and Num Lock has no
keys work monitoring
backwards. facility to
determine the
state of these
keys. It
always
assumes they
are turned off
when the
workstation is
activated.
Trade keyboards.
Refer to the section on hang problems and check
for +5VDC or +12VDC shorts to ground . Resolve
this problem as described in that section.
If the problem only occurs when a local printer or
other local device is connected, check the revision
of the workstation board. Look on the board for
a small box containing a single handwritten letter.
If the letter is M or less (A, B, C, etc.), modify
the board as follows. Change resistor R28 (located
behind the DB15 connector ) from 120 ohms to 4.7K
ohms.
Turn off these keys before resetting a workstation or
signing off.
DIMENSION Service Manual 2-49