Tandy CM-4 User Manual

8.
Color
Purity
Adjustment
The display
monitor
must
have
been
operating 15
minutes
prior to
this
procedure, and with
the
faceplate
of
the CRT at
room temperature.
The display
monitor
is
equipped with an
automatic degaussing
circuit.
However, if the
CRT
shadow mask
has become
exces-
sively magnetized,
it
may be
necessary
to
degauss
it
with
a
manual
coil.
Do
not switch the
coil
off
while
the
raster shows
any effect
from
the
coil.
1
.
Check for
the correct location
of
all
neck
compo-
nents. Refer
to Figure 13.
2.
Rough in the
static convergence
at the center of
the CRT,
as
explained
in
the
static
convergence
procedure.
3.
Rotate
the
contrast control
to the
center
of
its
range
and
rotate the brightness
control
to its
max-
imum
clockwise position.
4. To
obtain a
blank raster,
disconnect E
from
PCB-A.
Rotate
the
screen control
(part
of
T602)
clockwise
until
a
normal
raster is
obtained.
5.
Rotate the
red bias
(R862)
and blue
bias (R864)
controls
to the maximum
counterclockwise
po-
sitions.
Rotate
the
green
bias control
(R863) sufficiently
in a
clockwise
direction
to
produce
a
green raster.
6.
Loosen
the deflection
yoke
clamp
screw
and
pull
the deflection yoke as
close
as
possible
to
the pu-
rity and
convergence
magnets
assembly.
7.
Begin
the following
adjustment
with the
tabs
on
the
round
purity
magnet
rings
set together. Initial-
ly, move the
tabs
on the
round
purity magnet
rings
to the
side of
the CRT
neck.
Then, slowly separate
the two
tabs while
at
the
same
time
rotating them
to
adjust for
a
uniform green
vertical
band at the
center
of the CRT
screen.
Refer
to
Figure
12.
8.
Carefully
slide
the
deflection yoke
forward to
achieve
green purity (uniform
green screen).
Note:
Center purity
is obtained
by adjusting the
tabs on
the
round
purity
magnet rings.
Outer edge
purity
is obtained
by sliding
the
deflection
yoke
forward.
Tighten
the deflection yoke
clamp
screw.
9.
Check for
red
and
blue-field
purity
by
reducing the
output of the green bias
control
(R863)
and alter-
nately
increasing the output
of the
red
(R862) and
blue
(R864) bias
controls,
and touch
up the
ad-
justment, if
required.
10.
Reconnect E
to
RCB-A.
11.
Perform
the "Black and
White
Tracking"
procedures.
DEFLECTION
YOKE
CLAMP SCREW
GREEN
RASTER
Figure
12.
Color
Purity
Adjustment
r
PURITY
MAGNETS
FOUR-POLE
CONV.
MAGNETS
SIX-POLE,
CONV.
MAGNETS
45.9mm
(1.807
inches)
DEFLECTION
YOKE
DEFLECTION
YOKE
TILT
ADJUSTMENT
WEDGE
Figure
13.
Picture Tube
Neck Components Location
15

Tandy CM-4 Specifications

General

Brand	Tandy
Model	CM-4
Category	Monitor
Language	English