VISUAL
TECHNOLOGY
INCORPORATED,
540
MAIN
STREET,
TEWKSBURY,
MA
01876
7.9 TROUBLESHOOTING
7.9.1 Self Test
The Visual 100 contains a self test feature which
is
activated
each
time the terminal
is
turned on.
When
the terminal
is
turned on, the Local LED
is
illuminated, the RAM, the
non-volatile RAM and the PROMs
are
checked. Upon successful completion, the bell
is
sounded once, the
screen
is
initialized (cursor displayed), and either the Local or Line LED
is
illuminated depending upon which state
was
previously stored in the non-volatile
memory.
7.9.2 Fault Isolation
Operation
Turn
On
Turn
On
Self test
complete
No
cursor
Bell sounds
in local
No height
No
width
Video
tilted
Video
size
too
small
Video
jittering
Keyboard
No
data
Fault
No
line
or
Local
LED
LED's other than
Line or Local
On
or
bell rings
5 times
No Cursor
No Cursor
Horizontal line
on
TV
Vertical line
on
TV
Yoke adjustment
TV
monitor
Wrong Frequency
No entry
Line
or
Local
Probable
Cause
Keyboard
not
plugged in
Line cord
not
plugged in
Circuit Breaker tripped
Defective Logic
PCB
Self test failure
Brightness set
too
low
TV
cable disconnected
Flyback disconnected
CRT connector disconnected
Defective
TV
PCB
Defective Logic
PCB
Yoke disconnected
Yoke disconnected
Yoke rotated from normal
position
Yoke moved
too
far back
Vert.
size
adjustment
Horiz.
size
adjustment
50/60
Hz.
parameter
incorrect
Terminal
On
Line
Defective keyboard
Defective Logic
PCB
Keyboard disconnected
Defective keyboard
Defective Logic
PCB
60
Remedy
Plug
in
Plug in
Reset
Replace
Seat
PROMs
Replace
Logic
PCB
Adjust (SET-UP A, t Key)
Plug
in
Plug in
Plug in
Replace
Replace
Plug in yellow-black
connector
Plug in blue-red
connector
Adjust
Adjust
Adjust
Adjust
Set (SET-UP
B)
Switch
to
Local
Replace
Replace
Plug in
Replace
Replace
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