Chapter 5. Display Image Adjustments
Before checking
the
following adjustments, determine
that
all
voltages are within tolerance (see
MAP
01,
step 028), set the
Normal/Test switch
to
the
Test
position
to
display the test pattern, and install the
alignment mask
(PN
1743248) on the display screen.
5.1 Yoke
Alignment and Centering
Disable vertical deflection
by installing jumpers
on
the analog card test points (see Figure 4-6). Jumper
test point A
to
C and C
to
B,
or wrap a bare wire
around
all
four pins. A single horizontal trace should
be
displayed. This trace should be parallel to, and
vertically and horizontally centered on,
line 1 on
the
alignment mask.
If
the trace
is
not parallel
to
line 1,
the yoke must be aligned.
If
the trace
is
not centered,
the centering rings must be adjusted
(see
Figure 5-2).
In
either case, the CRT cone shield must be removed
before the adjustment
is
made.
5.1.1 Remove
Cone Shield. To remove the cone
shield, do the following after removing
the
top
and
side covers:
I
DANGER
Switch off
the
3278, and then disconnect the power
cord.
1.
Remove the socket from the base of the CRT
(see Figure 5-1).
2.
Loosen the cone shield retaining screw (see
Figure 5-1), rotate the cone
shield counterclock-
wise until the locking tabs disengage, and pull the
cone
shield straight back
to
clear the CRT neck.
Do
not remove the yoke or yoke shield.
3.
Reseat
the
socket on the CRT base, connect
the
power cord, and
turn
on the 327&
5.1.2 Yoke Alignment. To adjust the yoke align-
ment, do
the
following:
1.
Loosen the yoke clamp screw (see Figure 5-2).
2.
Rotate
the
yoke by turning the yoke shield until
the horizontal trace
is
parallel
to
line 1 on the
alignment mask.
3.
Be
sure
the
yoke
is
firmly seated against
the
CRT
bell, and tighten
the
yoke clamp screw.
SV27-2510-6
(1/81)
5-1
To Next Page
Loading...
Need help?
General
