DEC VT420 Service Manual page 78

2 Index
Monitor adjustments (Cont.)
focus, 50
horizontal width, 49
rotation, 47
screen control, 47
subcontrast, 47
test pattern, 46
vertical height, 49
vertical linearity, 49
N
North American model, 1
components, 63
model numbers, 58
pin assignments, 64
O
Olivetti parts, 59, 60
Operating modes, 2
P
Power-up self-test, 4, 13 to 14
Printer port loopback test, 18
Protective gear, 38
R
Recommended spares, 60
Removing FRUs, 22 to 41
CRT disposal, 38
CRT/yoke/bezel assembly, 26
keyboard, 36
terminal board assembly, 34
top cover, 22
Rotation adjustment, 47
RS-232 port control lines loopback
test, 17
RS-232 port data lines loopback test,
16
S
Screen alignment, 42 to 45
Screen alignment pattern, 18
Screen control adjustment, 47
Screen display problems
blank screen, 7
distorted or jittery, 7
ghost characters, 8
horizontal or vertical lines, 7
off center or rotated, 7
reverse question marks, 9
wrong characters displayed
local mode, 8
on-line, 8
Screen is blank, 6
Scrolling problems, 7
Self-tests, 10 to 21
DEC-423 port loopback, 14
power-up, 13
screen alignment pattern, 18
selecting local mode, 11
Set-up, using
displaying set-up screens, 51
Set-up cursor missing, 10
Set-up screens, using, 51 to 53
Subcontrast adjustment, 47
T
Terminal board assembly removal,
34
Testing, 10 to 21
Tools required, vii
Top cover removal, 22
Troubleshooting, 4 to 10
table of problems and solutions, 6