Kortek KT-1903NA Manuel utilisateur
SERVICE MANUAL
COLOR CRT MONITOR
KT-1903NA / KT-1703NA
KT-1403NA
KORTEK CORPORATION
DOC. NO KT-XX03NA-SM
DATE 2004 .02. 02
REV. NO 0
REV. DATE -
2
CONTENTS
1.PRECAUTIONS ****** 3
2.PRODUCT SPECIFICATIONS ****** 6
3.OPERATING INSTRUCTIONS ****** 10
4.ADJUSTMENT ****** 10
5.BLOCK DIAGRAM ****** 12
6.GENERAL THEORY OF OPERATION ****** 13
7.TROUBLE SHOOTING GUIDE ****** 26
8.WAVE FORM ****** 33
9.BILL OF MATERIAL ****** 36
10.SCHEMATICS ****** 51
3
1.PRECAUTIONS
1-1 SAFETY PRECAUTIONS
WARNINGS : Service should not be attempted by anyone unfamiliar with the necessary
precautions on this monitor. The following precautions are necessary during
servicing.
1) For continued safety, do not attempt to modify the circuit board.
2) Disconnect the AC Power before servicing.
3) When the Monitor is operating, do not touch any heatsink on the Chassis as it is self-heated.
1-1-1 FIRE & SHOCK HARZARD
1) During servicing, pay attention to the original wires whether it is uncoated or undressed,
especially the wires in the high voltage circuit section. If there is any uncoated or melted
wire is found, then please do not try to replace the related parts, and wait for the qualified
service person's coming.
2) Many electrical, mechanical parts in this monitor have special safety-related characteristics for
protection against shock hazard and others. These characteristics are often passed unnoticed
by a visual inspection and the protection afforded by them cannot necessarily be obtained
by using replacement components rated for higher voltage wattage,etc.
Replacement parts which have these special characteristics are identified in the manual and
supplements by shading on the schematic diagram and the parts list.
3) When replacing Chassis, always be certain that all the protective devices are installed
properly.
4) leakage current check (figure 1)
KORTEK Corporation
KT-XX03NA
4
(TEST METHODE)
1-1-2. X-RADIATION
WARNING : The only potential source of x-radiation is the picture tube, however
when the high voltage. Circuitry is operating properly, there is no possibility
of an x-radiation problem. The basic precaution is to keep the high voltage
at the factory recommended level.
1) To measure the high voltage, use a high-impedance high-voltage meter.
Connect(-) to chassis and (+) to the CRT anode cap.
2) Turn the contrast control max. clockwise.
3) Measure the high voltage. The high voltage meter should indicate the following factory
recommended level
4) If the actual level exceeds the max. factory set level, then immediate service is required to
prevent the possibility of premature failure of components
5) To prevent X-RADIATION possibility, it is essential to use the specified picture tube.
6) The nominal high voltage is 24KV and not exceed 27KV at zero beam current at rated voltage.
KORTEK Corporation
KT-XX03NA
DEVICE
UNDER
TEST LEAKAGE CURRENT
TESTER
READING SHOULD
NOT BE ABOVE 0.45mA
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE
CORD
ALSO TEST WITH PLUG
REVERSED(USING AC
ADAPTER PLUG AS
REQUIRED)
EARTH
GROUND
Figurel 1
5
1-2. SERVICING PRECAUTION
WARNING 1 : First, reading "safety precaution" section of this manual. If unforeseen
circumstances create conflict between the servicing precautions and safety
precaution, always follow the safety precautions.
WARNING 2 : A high voltage VR replaced in the wrong direction may cause excessive
X-RAY Emitting.
WARNING 3 : An electrolytic capacitor installed which the wrong polarity might explode.
1) Servicing precautions are printed on the label, and should be followed closely.
2) Always unplug the AC power cord from the AC power source before attempting to remove
or reinstall any component or assembly, disconnect PCB plugs or connectors, connect all test
Components in parallel which an electrolytic capacitor.
3) After servicing, always check that the screw, components and wiring have been correctly
reinstalled. Make sure that the area around the serviced part has not been demaged.
4) Check the insulation between the blades of the AC plug and accessible conductive
parts(example : metal parts, input terminals)
5) Never touch any of the locked B+ voltage. Do not apply AC power to the unit(or any of its
Assemblies) unless all solid-state heatsinks are correctly installed.
6) Always connect a test instrument's ground lead to the instrument chassis ground before
connecting the positive lead; always remove the instrument's ground lead last.
KORTEK Corporation
KT-XX03NA
6
2.Product Specifications
2-1 SPECIFICATION
PARAMETER MIN TYP MAX UNITS
OPERATING VOLTAGE 100 115/230 230 VAC
OPERATING POWER 85 90 WATTS
LEAKAGE CURRENT TO CHASSIS GND
AT250VAC,50/60Hz(LINE/NATU,IN COMMON)
< 0.40 0.45 mA
HI-POT LINE/NEUT, IN COMMON < 2.0 2.4 mA
OPERATING TEMPERATURE 10 60 DEGREE
REL,HUMIDITY OPERATING 10 90 %
MAGNETIC SHIELD INTERNAL
DEGAUSSING MANUAL TYPE
VIDEO SIGNAL +0.7Vpp, 75 Ohm MONITOR TERMINATIONS
RASTER DIM ADJUST RANGE VERTICAL < 190 > 290 mm
RASTER DIM ADJUST RANGE HORIZONTAL < 300 > 350 mm
MODE 640*480
PINCUSHION(ALL BRIGHTNESS) 3.0 %
MIS-CONVERGENCE CENTER 0.25 0.3 mm
MIS-CONVERGENCE CORNERS 0.35 0.45 mm
VERTICAL
SCAN RATE 60/70 Hz
HOLD IN RANG ±5 Hz
SYNC +5V 74LS LEVELS 5.0 5.0 VOLTAGE
LOW 0.0 0.0 0.6 VOLTAGE
NON-LINEARITY 5 %
HORIZONTAL
SCAN FREQUENCY 31.2 31.4 31.6 Khz
HOLD IN RANG ±500 Hz
SYNC POLARITY POSITIVE
SYNC +5V 74LS LEVELS 5.0 5.0 5.0 VOLTAGE
LOW 0.0 0.0 0.6 VOLTAGE
NON-LINEARITY 5 %
WHITE BALANCE & LUMINANCE X= 281 ±20 y= 311 ±20 Y = 10 ±3 F/L
Y=56 ±5 F/L
KORTEK Corporation
KT-XX03NA
7
2-2 PCB DIMENSIONS
1)MAINPCB
KT-XX03NA
KORTEK Corporation
8
2)SOCKET PCB
KT-XX03NA
KOREK Corporation
P_NO PIN_NAME P_NO PIN_NAME
1RED VIDEO 9NC
2GREEN VIDEO 10 SHIELD GND
3BLUE VIDEO 11 SHIELD GND
4NC 12 NC
5NC 13 H-SYNC
6RED GND 14 V-SYNC
7GREEN GND 15 NC
8BLUE GND
2-2-1 15-PIN SIGNAL CABLE CONNECTOR 2-2-2 PIN DESCRIPTION
1
6
11
9
2-3 TIMING CHART
A
HORIZONTALVIDEO
BC D
HORIZONTALSYNC
F
VERTICAL VIDEO
VERTICAL SYNC
NO 1 2 3 4
MODE IGT IBM VGA IBM VGA IBM VGA
H 640 640 720 640RESOLUTION
V 480 350 400 480
H POSI POSI NEGA NEGASYNC POLARITY
V POSI NEGA POSI NEGA
FREQUENCY ㎑ 31.469 31.469 31.469 31.469
PERIOD ㎲ 31.777 31.777 31.777 31.777
SYNC ㎲ 3.813 3.813 3.813 3.813
B/P ㎲ 1.907 1.094 1.907 1.907
H
ACTIVE ㎲ 25.422 25.422 25.422 25.422
FREQUENCY ㎐ 59.941 70.087 70.087 59.941
PERIOD ㎳ 16.683 14.268 14.268 16.683
SYNC ㎳ 0.064 0.064 0.064 0.064
F/P ㎳ 1.049 1.907 1.080 1.049
V
ACTIVE ㎳ 15.253 11.122 12.711 15.253
FIXEL FREQUENCY ㎒ 25.175 25.175 28.322 25.175
INTERACE NO NO NO NO
KT-XX03NA
KORTEK Corporation
10
3. OPERATING INSTRUCTIONS
3-1 LOCATION FUNCTION OF CONTROL PCB ASS'Y
4.ADJUSTMENT
4-1 ADJUSTMENT CONTROL
1) Orientation
When servicing, always face the monitor to the east
2) Warm-up time
The monitor must be on for 30 minutes before starting alignment. Warm-up time is
especially critical in color temperature and white balance adjustments.
3) Signal
Analog 0.714vpp positive at 75Ω, internal termination.
4) B+ line adjustment
Signal in; adjust in order to 54 ±0.2V
5) Screen adjust(FBT) : 550 ±20V
KORTEK Corporation
KT-XX03NA
Ce manuel convient aux modèles suivants
2
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