Schneider Computer Division CTM 644 Farb-Monitor, Руководство по обслуживанию

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Vertical size
adjustment
Adjust the control (VR 406) so
that picture fills the picture open­
ing from top to bottom and is
proportionate to the width.
Focus adjustment
Adjust focus control, on the
flyback transformer, for maxi­
mum overall definition and fine
detail with brightness control set
at normal viewing levels.
5-V adjustment
The 5-V adjustment control (VR
501) is adjustment at the factory.
However, should readjustment
be required, proceed as follows:
1. Connect positive lead of volt­
meter to 5-V adjust point,
negative
lead to chassis
ground and then input AC 225
V.
2. Adjust VR 501 to obtain a
5-V reading.
Caution:
To insure proper operation and
circuit reliability, do not exceed 5
V.
Sub bright adjustment
1. Set the colormonitor to no­
signal
position.
2. Set bright control to maximum
position.
3. Connect voltmeter to collector
of Q 802.
4. Adjust VR 402 to obtain a
120-V reading.
Sub H-Hold and
H-Hold adjustment
1. Receive the snowy station
(free-run).
2. Connect frequency counter to
CRT heater.
3. Rotate H-Hold control fully
counter-clockwise.
4. Adjust VR 404 to obtain 14500
Hz reading.
5. Adjust H-Hold control (VR
403) to obtain 15625 Hz rea­
ding.
Color purity adjustment
The receiver must have been
operating 10 minutes prior to this
procedure and the face
plate of
the CRT must be at room tempe­
rature. The following procedure
is
recommended while using a
Dot/Bar Generator.
1. Check for correct location of
all neck components (refer to
Figure 2).
2. Rough-in the static conver­
gence at the center of the
CRT, as explained in the
static
convergence.
3. Rotate the contrast control to
maximum CCW position and
rotate brightness control as
for CW as possible without
causing the picture to
“bloom ”.
4. Rotate the red bias and blue
bias controls to maximum
CCW position. Rotate the
green bias control sufficiently
in a CW direction to produce a
green raster.
5. Loosen the deflection yoke
clamp screw and pull the
deflection yoke toward the
rear of the CRT.
6. Begin the following adjust­
ment with the tabs on the
round purity magnet rings set
together, slowly separate the
two tabs while at the same
time rotating them to adjust for
a uniform green stripe at the
center of the CRT screen.
7. Carefully slide the deflection
yoke forward to achieve green
(uniform green screen).
Note:
Center purity was obtained by
adjusting the tabs
on the round
purity magnet rings, outer edge
purity was obtained by sliding
the deflection yoke forward.
8. Check for red and blue field
purity by reducing the output
of the green bias control and
alternately increasing output
of
red and blue bias controls
and touch up adjustments, if
required.
9. Tighten deflection yoke clamp
screw.
Figure 2. Picture Tube Neck
Component Location
Black and white
tracking
The purpose of this procedure is
to adjust the biases applied to
the picture tube to obtain good
black and white picture produc­
tion at all brightness levels while,
at the same time achieving
maximum useable brightness.
1. Rotate the Red and Blue
Drive control fully CW and
then back CCW center of
their rotation ranges.
2. Rotate the Green, Red and
Blue Bias controls to the full
CCW end of their rotation
ranges.
3. Set normal-service switch to
voltage of test point (collector
of green output transistor on
CRT PCB) to DC 120 V with
brightness control. Voltage
should be measured with
oscilloscope.
4. Rotate the screen control to
the full CCW end of its rota­
tion range. Then, rotate it
CW until a dim line of one
pronounced
color (green,
red or blue) is obtained.
5. The other two color bias
controls must be rotated CW
until a dim white line is
obtained.
6. Set normal-service switch to
normal position.
7. If required, touch-up adjust­
ment of the Red and Blue
Drive
controls to produce a
uniform monochrome
picture.
8. Rotate the brightness and
contrast controls fully CCW.
9. Rotate the brightness control
CW until a dim raster is
obtained.
10. If the screen does not display
good while uniformity, step 2
through 10 of this procedure
must be repeated.
Dynamic convergence
adjustment
Dynamic convergence (conver­
gence of the three color fields at
the edges of the CRT screen) is
accomplished by proper inser­
(B G R)
Figure 3 Dynamic Conver­
gence Adjustment
tion and positioning of three
rubber wedges between the
edge of the deflection yoke and
the tunnel of the
CRT. This is
accomplished in the following
manner. .
1. Switch the Receiver on and
allow it to warm up for 15
minutes.
2. Apply crosshatch pattern from
Dot/Bar Generator to receiv­
er. Observe spacing between
lines around edges of CRT
screen.
3. Tilt the deflection yoke up or
down, and insert tilt adjust­
ment wedges (1) and (2)
between the defliction yoke
and the CRT until the miscon­
vergence illustrated in Figure
3 (A) has been corrected.
4. Tilt the deflection yoke right
and left, and insert tilt adjust­
ment wedge
(3) between the
deflection yoke and the CRT
until the misconvergence
illustrated
in Figure 3 (B) has
been corrected.
5. Altertely change spacing
between, and depth of inser­
tion of the three wedges so
proper dynamic convergence
is
obtained.
6. Use a strong adhesive tape to
firmly secure each of the three
wedges to the funnel of the
CRT.
7. Check purity and readjust, if
necessary.
service position. Adjust the
4