CTX CMS-3436 - Voltage Checks and Sync;Deflection Adjustments; High Voltage and Horizontal Center Adjustments; Vertical Linearity and Size Adjustments

When
adjusting
the
monitor,
receive
a
full
screen
white
pattern
set
at 20
ft-L
unless
otherwise
speci-
fied.
1. Power Supply Voltage Check
When the monitor is working normally, the vol-
tages at plug P301 on main board are as follows:
v1
V2
V3
95V+ 0.5V for video o/p AMP
Ground
21V+ 0.5V for vertical o/p AMP
Voltages at P405 on interface board are as fol-
lows:
B1
B2
B3
(1)
(2)
(3)
(4)
12V 0.5V for deflection IC & video preamp
Ground
6V+ 0.1V for heater and logic circuits
Receive VGA 400 lines Signal with full
white pattern.
Adjust VR101 to obtain 95V+0.5V.
Adjust VR102 to Mechanical center position.
Adjust VR103 to obtain 6V+0.1V.
2. Sync and Deflection Circuit
2.1
(1)
(2)
(3)
2.2
(1)
(2)
(3)
(4)
(6)
(6)
Horizontal Frequency Conversion Circuit
Receive VGA (400 lines) Signal with full
screen white pattern.
Adjust VR303 to obtain 16V+0.2V on TP1.
Adjust VR304 to obtain 12.2V+0.1V on TP6.
Horizontal Oscillation
Receive VGA (400 lines) Signal with cross
hatch pattern.
Bypass the sync signal by connecting a 10u
/25V capacitor to TP2 and ground, capacitor
positive side is on TP2.
Adjust VR302 to make the picture stand still
or move slowly toward left or right.
Receive CGA signal with cross hatch pattern.
Adjust VR307 to make the picture stand still
or move slowly toward left or right.
Disconnect 10u/25V capacitor, check mon-
itor picture be steady when receiving display
modes range from standard VGA up to
8514A, if not, repeat procedures (1) through
(5) more carefully.
2.3 Vertical Oscillation
(1)
(2)
(3)
(4)
Receive VGA (400 lines) signal with cross
hatch pattern.
Adjust VR208 to obtain 7.8V+0.2V on TP8.
Disconnect VGA input signal.
Adjust VR218 to obtain 50Hz+1Hz vertical
free-run oscillation. Use counter or scope to
measure frequency on the positive side of
the vertical deflection coil, which is easily
accessed on one of the yoke assembly con-
tact points.
14
2.4 High Voltage Circuit
(1)
(2)
(3)
(4)
Receive VGA (400 lines) signal with full
screen.
Adjust contrast and bright controls to mini-
mum intensity.
Adjust VR310 to obtain 31.4V+0.2V on TP7.
This
reading
is
approximately
equivalent
to
24KV of CRT Anode High Voltage.
In some extreme cases, TP7 may not reach
31.4V
when
adjusting
VR310.
It’s
because
the
VR102
adjustment
limits
the
DC
voltage
supply to FBT, so put the VR310 in mecha-
nical center position, then adjust VR102 for
TP7 to be 31.4V+0.2V.
Adjust VR309 to obtain 8.2V+0.1V on TP9,
this will set the X-ray protector to hold
down the horizontal deflection output when
the Anode High Voltage exceeds 29KV.
2.5 Horizontal Center
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Receive VGA (400 lines) signal with full
screen white pattern.
Adjust VR301 to ensure that the external
H.
Center
control
VR308
has
a
symmetric
range
to
shift
the
picture
toward
left
and
right
then
adjust
VR308
to
put
the
picture
in the center of the screen.
Receive EGA signal with full screen white
pattern.
Adjust VR306 to put the picture in the center
of the screen.
Receive CGA signal with full screen white
pattern.
Adjust VR305 to put the picture in the center
of the screen.
Receive 1024X768 signal with full screen
white pattern.
Adjust VR311 to put the picture in the center
of the screen.
2.6 Vertical Linearity
(1)
(2)
(3)
(4)
Receive VGA (400 lines) signal with cross
hatch pattern.
Adjust V. BIAS VR203 to the mechanical
center position.
Adjust VR206 so the top blocks are equal
to the bottom blocks.
Adjust VR205, so the center blocks are
equal to the top and bottom blocks.
2.7 Vertical Size
(1)
(2)
(3)
Receive 1024X768 signal with cross hatch
pattern.
Adjust the external user control VR201 clock-
wise
to
obtain
maximum
vertical
size.
Adjust VR202 to obtain full screen picture
height.