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Kortek KT-1903NA Service Manual

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COLOR CRT MONITOR
DOC. NO
KT-XX03NA-SM
DATE
2004 .02. 02
REV. NO
0
REV. DATE
-
SERVICE
MANUAL
KT-1903NA / KT-1703NA
KT-1403NA
KORTEK CORPORATION

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  • Page 1 COLOR CRT MONITOR DOC. NO KT-XX03NA-SM DATE 2004 .02. 02 REV. NO REV. DATE SERVICE MANUAL KT-1903NA / KT-1703NA KT-1403NA KORTEK CORPORATION...

  • Page 2: Table Of Contents

    CONTENTS 1.PRECAUTIONS ****** 2.PRODUCT SPECIFICATIONS ****** 3.OPERATING INSTRUCTIONS ****** 4.ADJUSTMENT ****** 5.BLOCK DIAGRAM ****** 6.GENERAL THEORY OF OPERATION ****** 7.TROUBLE SHOOTING GUIDE ****** 8.WAVE FORM ****** 9.BILL OF MATERIAL ****** 10.SCHEMATICS ******...

  • Page 3: Precautions

    KORTEK Corporation KT-XX03NA 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.
  • Page 4 KORTEK Corporation KT-XX03NA READING SHOULD NOT BE ABOVE 0.45mA DEVICE UNDER TEST ALL TEST LEAKAGE CURRENT EXPOSED METAL TESTER SURFACES 2-WIRE CORD ALSO TEST WITH PLUG REVERSED(USING AC EARTH ADAPTER PLUG AS GROUND REQUIRED) Figurel 1 (TEST METHODE) 1-1-2. X-RADIATION WARNING : The only potential source of x-radiation is the picture tube, however when the high voltage.
  • Page 5 KORTEK Corporation KT-XX03NA 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.

  • Page 6: Product Specifications

    KORTEK Corporation KT-XX03NA 2.Product Specifications 2-1 SPECIFICATION PARAMETER UNITS OPERATING VOLTAGE 115/230 OPERATING POWER WATTS < 0.40 LEAKAGE CURRENT TO CHASSIS GND 0.45 AT250VAC,50/60Hz(LINE/NATU,IN COMMON) < 2.0 HI-POT LINE/NEUT, IN COMMON OPERATING TEMPERATURE DEGREE REL,HUMIDITY OPERATING MAGNETIC SHIELD INTERNAL DEGAUSSING...
  • Page 7 KORTEK Corporation KT-XX03NA 2-2 PCB DIMENSIONS 1) MAIN PCB...
  • Page 8 KOREK Corporation KT-XX03NA 2)SOCKET PCB 2-2-1 15-PIN SIGNAL CABLE CONNECTOR 2-2-2 PIN DESCRIPTION P_NO PIN_NAME P_NO PIN_NAME RED VIDEO GREEN VIDEO SHIELD GND BLUE VIDEO SHIELD GND H-SYNC RED GND V-SYNC GREEN GND BLUE GND...
  • Page 9 KORTEK Corporation KT-XX03NA 2-3 TIMING CHART HORIZONTAL VIDEO HORIZONTAL SYNC VERTICAL VIDEO VERTICAL SYNC MODE IBM VGA IBM VGA IBM VGA RESOLUTION SYNC POLARITY POSI POSI NEGA NEGA POSI NEGA POSI NEGA FREQUENCY ㎑ 31.469 31.469 31.469 31.469 PERIOD ㎲...

  • Page 10: Operating Instructions

    KORTEK Corporation KT-XX03NA 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.
  • Page 11 KORTEK Corporation KT-XX03NA 4-2 DISPLAY CONTROL ADJUSTMENTS A. SELECT H-SIZE FUNCTION, ADJUST HORIZONTAL SIZE 350mm±3mm(V/R404) B. SELECT V-SIZE FUNCTION, ADJUST VERTICAL SIZE 250mm±3mm(V/R304) C. SELECT H-POSI FUNCTION, ADJUST TO CENTER THE PATTERN WITHIN THE RASTER (V/R305) D. SELECT V-POSI FUNCTION, ADJUST TO CENTER THE PATTERN WITHIN THE RASTER(V/R501) E.

  • Page 12: Block Diagram

    KORTEK Corporation KT-XX03NA 5. BLOCK DIAGRAM VIDEO VIDEO PRE-AMP DRIVE KA2141 SIGNAL CONTROL AUTO BIAS 74LS86 VERTICALOUT H/V PROCESS TDA8172 TDA9102C S-CORRECTION 125V POWER SUPPLY SCREEN 6.3V FOCUS...

  • Page 13: General Theory Of Operation

    KORTEK Corporation KT-XX03NA 6. GENERAL THEORY OF OPERATION 6-1 BLOCK DIAGRAM Above is the block diagram of the monitor as a whole. Each major section is presented in a block. The individual circuit that makes up the section is covered later and is not shown here.
  • Page 14 KORTEK Corporation KT-XX03NA Video signal (0.7V PP) supplied from "CN901 Pin 2 (BLUE), 4(GREEN), 6(RED)" is supplied to IC901 Pin 4, 6, 8 through "C902, C903, C905." IC901 performs VIDEO PRE AMP and its amplitude is “determined by DC BIAS of Pin 1, 2, 3. Pin 9 (Contrast) controls its output video level.
  • Page 15 KORTEK Corporation KT-XX03NA 6-4 G2 CONTROL CIRCUIT SECTION G2 control circuit complements operations of auto bias circuit and when replacing CRT, it is not necessary to adjust screen voltage. For circuit operations, R. G. B cathode voltage of CRT is detected through R936, R931 and R933. When the voltage is applied to Q904 base, Q904 automatically controls screen voltage to maintain screen brightness at a constant level.
  • Page 16 KORTEK Corporation KT-XX03NA CRT cathode is composed of three electrodes of R, G and B and GRID 1 electrode is also composed of three electrodes. Three electrodes maintain different separations from each other and the voltage proportional to each separation should be supplied to obtain the constant color.
  • Page 17 KORTEK Corporation KT-1903NA R924 and R922, and outputs it to IC902 Pin 7. Output waveform, with not much current, is amplified with using OP amp and output to Pin 1. Finally it is supplied to auto bias control circuit. 6-7 SMPS CIRCUIT SECTION Power supply is composed of line filter, switching amp and switching trans circuit.
  • Page 18 KORTEK Corporation KT-XX03NA IC101 pin 1 has OSC function embedded in chip so that, at the first time when power switch is turned on, embedded OSC oscillates to drive circuits. After the initial operation, it inputs pulse separated flowing out from FBT in IC101 Pin 5 to match frequencies of monitor and power supply so that it minimizes noise from oscillation and from interference between frequencies of monitor and power supply.
  • Page 19 KORTEK Corporation KT-XX03NA This is a circuit using temperature characteristics of PH101, and when power is turned on, high voltage is applied momentarily and current flows. At this time, heat is generated and temperature rises. With rising temperature, as much as resistance increases and after about 20 seconds, current stops flowing and this circuit stops operating.
  • Page 20 KORTEK Corporation KT-XX03NA Pin 5 supplies sync input from outside to Pin 5 through embedded interface and at this time, according to capacitor value of C305 connected to Pin 5, pulse width is determined. Pin 6 outputs horizontal output pulse and its range is from 27Khz to 70Khz.
  • Page 21 KORTEK Corporation KT-XX03NA 6-9. SYNC CONTROL CIRCUIT This SYNC control circuit converts SYNC to maintain constant level is always input regardless whether SYNC is input or not. For the function, the circuit is composed of chip embedding four exclusive or gate circuits.
  • Page 22 KORTEK Corporation KT-XX03NA 6-10 VERTICAL OUTPUT CIRCUIT SECTION IC501 amplifies sawtooth waveform output from TDA9102 Pin 15 and supplies it to deflection yoke. IC501 uses Pin 5 to output the amplified wave. IC501 Pin1, receiving sawtooth waveform output from TDA9102 Pin15, amplifies and output it through amplifier embedded in chip and supplies it to reflection yoke.
  • Page 23 KORTEK Corporation KT-XX03NA 6-11 HORIZONTAL DRIVE & OUTPUT CIRCUIT SECTION Horizontal drive receives pulse from TDA9102C Pin 6 (varies according to frequency) and applied to Q401 base. Then Q401 repeats on and off according to the pulse. At this time, pulse is generated in T401 and operates T401.
  • Page 24 KORTEK Corporation KT-XX03NA 6-12 KT-1903NA adjustment method 1. B+ voltage adjustment method 1) Measuring terminal : D114 CATHODE side 2) Adjusting V/R : V/R101 : 54 ± 0.2V 3) Adjusting voltage 4) Measuring condition : AC 120 V, 60 Hz ,CROSS HATCH PATTERN : 6.2 ±...
  • Page 25 KORTEK Corporation KT-XX03NA 5. Horizontal RASTER position adjustment 1) Adjustment V/R : V/R401 2) Adjustment position : center of screen 6. Check of coordinates value 1) Adjustment position : center of screen(measured as CA-100 in CRT face) 2) Measuring condition : After adjusting Back Roaster into 0.1 F/L by varying of screen at Cross Hatch, measurement is made at max 70 F/L in Window pattern X : 281 ±...

  • Page 26: Troubleshooting Guide

    KORTEK Corporation KT-1903NA 7. TROUBLESHOOTING GUIDE 7-1 NO-POWER N O - P O W E R C H E C K F 1 0 1 C H A N G E F U S E C H E C K D 1 0 1...
  • Page 27 KORTEK Corporation KT-1903NA 7-2 NO-VIDEO N O - V IDE O CH E CK R , G,B S IGNAL CH AN GE S IGNAL CABLE CH E CK IC901 CH AN GE IC901 CH E CK 12V CH E CK & CH AN GE CH E CK &...
  • Page 28 KORTEK Corporation KT-1903NA 7-3 NO SYNC PROBLEM S Y N C P R OBLE M CH E CK IC201 CH AN GE IC201 CH E CK D 201,2 CH AN GE D 201,2 CH E CK IC301 CH E CK & CH AN GE CH E CK &...
  • Page 29 KORTEK Corporation KT-1903NA 8-4 VERTICAL DEFLECTION PROBLEM V E R TICAL D E FL E CT ION P R OBLE M CH E CK D 501 CH AN GE D 501 CH E CK IC501 CH AN GE IC501 CH E CK 24V CH E CK &...
  • Page 30 KORTEK Corporation KT-1903NA 7-5 HORIZONTAL DEFLECTION PROBLEM H OR IZO N TAL D E FL E C T ION P R OB LE M C H E C K IC 3 0 1 C H AN GE IC 3 0 1...
  • Page 31 KORTEK Corporation KT-1903NA 7-6 X-RAY FROTECTION PROBLEM X-RAY PROTECTION PROBLEM CHECK IC202 CHANGE IC202 CHECK C303 CHANGE C303 CHECK R324 CHECK & CHANGE R324 CHECK D301 CHANGE D301 CHECK CHANGE FBT...
  • Page 32 KORTEK Corporation KT-1903NA 7-7 AUTOBIAS PROBLEM AUTO BIAS PROBLEM CHECK IC902 CHANGE IC902 CHECK SG950 CHANGE S G950 CHECK DRIVE CHECK & CHANGE CHECK & CHANGE IC950 Q901,2,3 CHECK Q503 CHANGE Q503 CHECK Q950,1,2 CHANGE Q950,1,2...

  • Page 33: Wave Form

    KORTEK Corporation KT-1903NA 8.주요부위 파형 1)IC101(0880) PIN 1 OUTPUT WAVEFORM 2)IC101(0880) PIN 5 INPUT WAVEFORM 3) H-SYNC WAVE FORM 4)V-SYNC WAVEFORM 5)CLAMP WAVEFORM 6)VIDEO IN PUT WAVEFORM...
  • Page 34 KORTEK Corporation KT-1903NA 7)IC301 PIN 15 OUT PUT WAVEFORM 8) IC501 PIN 5 OUT PUT WAVEFORM 9)IC301 PIN 8 FLY BACK IN PUT WAVEFORM 10DYNAMIC FOCUS WAVEFORM 11) Q402 OUTPUT WAVEFORM 12)Q402 BASE WAVEFORM...
  • Page 35 KORTEK Corporation KT-1903NA 13) D403 WAVEFORM 14)D404 WAVEFORM 15) VIDEO IN PUT WAVEFORM 16) VIDEO_PREAMP OUT WAVW FORM "FULL WHITE" 17) VIDEO CATHODE OUT WAVE FORM 18) IC301_8P WAVE FORM...

  • Page 36: Bill Of Material

    KORTEK Corporation KT-1903NA 8.BILL OF MATERIAL DESCRIPTION SPECIFICATION LOCATION NO. JUMP WIRE 7.5mm J950, J950, J950 JUMP, WIRE 8 mm R720 JUMP, WIRE 8 mm J919, J921, J920, J911, J910 JUMP, WIRE 7.5 mm J103, J110, J113, J114, J118,J120, J121, J122, J127, J134,J135, J136,...
  • Page 37 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. HARNESS 190mm (2P, 3P)→38K CN701 160mm (4P)→CUTTING BEAD, CORE ATS3560L, 3.5*6mm BD101, BD401, J102 CABLE TIE SJCT-100mm CAPACITOR, CERAMIC 50V 102pF B "K" C906, C907, C908 CAPACITOR, CERAMIC 50V 103pF F "Z" C901, C910, C911, C912 CAPACITOR, CERAMIC 50V 104pF F "Z"...
  • Page 38 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. CAPACITOR, ELECTROLYTIC 50V 10uF KME (KMG) C902, C903, C905, C914 CAPACITOR, ELECTROLYTIC 200V 47uF KME (KMG) C913 CAPACITOR, ELECTROLYTIC 250V 1uF KME (KMG) C923 CAPACITOR, ELECTROLYTIC 100V 1uF (BP) KME (KMG) C921, C928, C931, C934 CAPACITOR, ELECTROLYTIC 50V 0.22uF (4*7.5mm) SRA...
  • Page 39 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. COIL, CHOKE 822 (8φ) L401 COIL, LINE FILTER LF-2828 L101 COIL, LINEARITY 17N 1 L402 COIL, PEAKING 151uH BD103, BD104 COIL, PEAKING 4.7uH (AL03 TYPE) L901, L902, L903 COIL, PEAKING 100uH (AL04 TYPE)
  • Page 40 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. G.T PIN 2.36mm HARNESS 500mm (12P COLOR) CN205 HARNESS 5P*5P*160mm 38K용 CN702 HARNESS, 2P ORANGE + RED 190mm, J2, J3↔CN206 HARNESS, 7P RING CORE(TO SOCKET) CN204 HEAT SINK JS 23-1 35mm Q901, Q902, Q903...
  • Page 41 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/2W 150 J R508 RESISTOR, CARBON 1/2W 270 J R117 RESISTOR, CARBON 1/2W 120K J R116 RESISTOR, CARBON 1/4W 1.5 J R507 RESISTOR, CARBON 1/4W 22 J R405 RESISTOR, CARBON 1/4W 27 J...
  • Page 42 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/4W 4.3K F R506 RESISTOR, CARBON 1/4W 5.6K F R503 RESISTOR, CARBON 1/4W 6.8K F R313, R509 RESISTOR, CARBON 1/4W 9.1K F J177 RESISTOR, CARBON 1/4W 10K F R332 RESISTOR, CARBON...
  • Page 43 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/2W 47 J R716 RESISTOR, CARBON 1/2W 100 J R715 RESISTOR, CARBON 1/6W 1K J R724 RESISTOR, CARBON 1/6W 4.7K J R723 RESISTOR, CARBON 1/6W 15K J R721, R722 RESISTOR, CARBON...
  • Page 44 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/6W 100 F R938 RESISTOR, CARBON 1/6W 8.2K J R922 RESISTOR, CARBON 1/6W 560K J R921, R923 RESISTOR, CARBON 1/6W 15K F R954, R954, R954 RESISTOR, CARBON 1/6W 1M F R955, R955, R955...
  • Page 45 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. SCREW, TAPPING TP3*8mm, CUT SCREW, TAPPING TP3*12mm, CUT SILICON PAD 20*25mm*0.45t FOR IC101 SOCKET PCS-626-01 PCS626-01 SOCKET PCB COVER 82.5 * 110mm SURGE ABSORBER BSD-201L SG902, SG903, SG904 SURGE ABSORBER BSD-201L SG950, SG950, SG950...
  • Page 46 KORTEK Corporation KT-1903NA DESCRIPTION SPECIFICATION LOCATION NO. WAFER FA 0640-08 CN950, CN950, CN950 WIRE, LEAD BLACK 40mm 1007 #24 ZD201↔C422...
  • Page 47 KORTEK Corporation KT-1903NA (UR) ※Parts list of KT-1903NA(UR) different from KT-1903NA(ST) DESCRIPTION SPECIFICATION LOCATION NO. JUMPER, WIRE C318 RESISTOR, CARBON 1/6W 330 J R210 RESISTOR, CARBON 1/4W 130K F R454 COIL, MAIN TRANS KTV-4042A,19NA5(53V) T101 CAPACITOR, AC EPOXY 250VAC 102pF, K...
  • Page 48 KORTEK Corporation KT-1703NA (UR) ※Parts list of KT-1703NA (UR) different from KT-1903NA (ST) DESCRIPTION SPECIFICATION LOCATION NO. BEAD, CORE ATS3560L, 3.5*6mm J124 COIL, INDUCTOR AL03 4.7uH LXXX (POWER TRANS PIN 8번) DIODE, RECTIFIER EGP20C, 150V 2A D111 DIODE, RECTIFIER 1N4148, 75V 150mA...
  • Page 49 KORTEK Corporation KT-1703NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/4W 1.8M J R452 RESISTOR, CARBON 1/2W 10 J R126 RESISTOR, CARBON 1/2W 470 J R508 RESISTOR, CARBON 1/2W 10K J R409 CAPACITOR, CERAMIC 50V 473pF F "Z" C115 CAPACITOR, ELECTRO...
  • Page 50 KORTEK Corporation KT-1703NA DESCRIPTION SPECIFICATION LOCATION NO. RESISTOR, CARBON 1/4W 15K J R332 RESISTOR, METAL 1W 1.2 J R125 RESISTOR, METAL 2W 2.2 J R123 RESISTOR, VARIABLE 2KB, RVM630H VR401 RESISTOR, VARIABLE 10KB, RVM630H VR403, Q302 SCREW, TAPPING TP3*8mm, 2 CUT...

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