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LG STUDIOWORKS 77M Service Manual

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LG
STUDIOWORKS 77M
MODEL
SERVICE MANUAL

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Summary of Contents for LG STUDIOWORKS 77M

  • Page 1 STUDIOWORKS 77M MODEL SERVICE MANUAL...

  • Page 2: Specifications

    SPECIFICATIONS 1. PICTURE TUBE 4. POWER SUPPLY Size : 17 inch (Flat Square Tube) 4-1. Power Range : In-line AC 100V ~ 240V (Free Voltage), 50/60Hz, 2.3A Max. DefIection Angle : 90° Neck Diameter : 29.1 mm 4-2. Power Consumption Dot Pitch : 0.27 mm MODE...

  • Page 3: Control Locations

    CONTROL LOCATIONS SW202 VR201 VR202 SW206 SW205 SW201 SW204 SW203 CONTROL SPEAKER SPEAKER MAIN MIC JACK EARPHONE JACK VR701 VR901 AUDIO MIC OUT AUDIO IN VIDEO Ref. No. Control Function Ref. No. Control Function SW202 ENTER BUTTON SW201 POWER SWITCH SW204 OSD SELECT RIGHT VR201...

  • Page 4: General Information

    ADJUSTMENT GENERAL INFORMATION All adjustment are thoroughly checked and corrected 8) DIST. ADJ. → FOS. ADJ → Mode No. → 1 command. when the monitor leaves the factory, but sometimes 9) Adjust V-SIZE as arrow keys to 230±2mm. several minor adjustment may be required. 10) Adjust V-POSITION as arrow keys to center of the Adjustment should be following procedure and after screen.
  • Page 5 7. Adjustment for Focus. 17) Display color 15,0 full white patten at Mode 4. 18) COLOR ADJ. → LUMINANCE → ABL command. 1) Display H character in full screen at Mode 4. 2) Adjust two Focus control on the FBT that focus 19) Adjust ABL to 35±1FL(MPR), 30±1(TCO) of the should be the best condition.

  • Page 6: Troubleshooting Guide

    TROUBLESHOOTING GUIDE 1. NO POWER NO POWER (POWER INDICATOR OFF) CHECK TROUBLE IN FUSE FUSE OK? (F901) CHECK C907 VOLTAGE? TROUBLE IN (AC120V: 170VDC, D901, D902, D903, D904 AC220V: 310VDC) CHECK IC901 PIN 3 TROUBLE IN WAVEFORM (SQUARE WAVE IC901, IC902 COMES OUT?) CHECK TROUBLE IN...
  • Page 7 2. NO CHARACTER NO CHARACTER CHECK TROUBLE IN IC302 PIN 7, 15, 18, P302 12V LINE, IC304 21(8V) ? TROUBLE IN CHECK PC SIGNAL, IC302 PIN 6, 8, 10 ? P301 SIGNAL CABLE CHECK TROUBLE IN IC302 PIN 16, 19, 22 ? IC302 CHECK TROUBLE IN...
  • Page 8 3. NO RASTER NO VIDEO (POWER INDICATOR ON) CHECK ORANGE DPM MODE POWER INDICATOR (NO H and/or V SYNC) GREEN or ORANGE? GREEN CHECK TROUBLE IN D712 ANODE D712 (-120V)? CHECK TROUBLE IN G1 VOLTAGE? Q801~Q806 (-10~20V) TROUBLE IN D926, Q925 (6.3V)
  • Page 9 4. NO HORIZONTAL DEFLECTION NO H-DEFLECTION (ONE VERTICAL LINE) TROUBLE IN CHECK Q706? Q706 CHECK TROUBLE IN B + VOLTAGE 160V LINE (160V)? CHECK TROUBLE IN T701(FBT) PIN 3 Q717, Q718, Q719, (31KHZ 70V, D707 69KHZ 140V) ? CHECK TROUBLE IN Q705 COLLECTOR Q705 WAVEFORM?
  • Page 10 5. TROUBLE IN H-LINEARITY UNBALANCED OF H-LIN. CHECK TROUBLE IN IC401 PIN 18, 19, 20? IC401 (MICOM) CHECK TROUBLE IN Q711~Q716? Q711 ~ Q716 CHECK TROUBLE IN L703? L703 Cs SIGNAL TABLE HORIZONTAK FREQUENCY(fH) TROUBLE IN 30K ~ 39K L720, R744 39K ~ 47.5K 47.5K ~ 62K 62K ~ 70K...
  • Page 11 6. NO VERTICAL DEFLECTION NO V-DEFLECTION (ONE HORIZONTAL LINE) CHECK TROUBLE IN IC601 PIN 3 R603, Q601~Q603, (15V)? 15V LINE CHECK TROUBLE IN IC601 PIN 7 HIGH-VOLTAGE OUT (40V)? CIRCUIT, D713 CHECK TROUBLE IN IC701 PIN 12, 13? IC701 TROUBLE IN IC601, V-CIRCUIT...
  • Page 12 7. TROUBLE IN OSD NO OSD (ENTER BUTTON MUST BE PRESSED.) CHECK TROUBLE IN IC301 B + ? 5V LINE DC 5V CHECK TROUBLE IN IC301 PIN 5, 10 IC601 PIN8 (V-FBP), WAVEFORM? T701 40V LINE Pin 10 Pin 5 CHECK TROUBLE IN IC311 PIN 12...
  • Page 13 8. TROUBLE IN DPM (NO OFF MODE.) OFF MODE FAILURE CHECK CHECK PC, IC401 (MICOM) INPUT H/V SYNC SIGNAL (PC IS NOT GOING INTO PIN 1, 42 (H/V INPUT) DPM OFF MODE) SIGNAL? NO H/V SYNC CHECK TROUBLE IN IC401 PIN 6 X401 WAVEFORM? 6MHz...
  • Page 14 9. NO DEGAUSSING NO DEGAUSSING (DEGAUSS ON THE OSD MENU MUST BE PRESSED.) CHECK TROUBLE IN IC401 PIN 22 IC401 (MICOM) (0V)? CHECK TROUBLE IN Q921 COLLECTOR Q921 VOLTAGE? DC 5V CHECK TROUBLE IN P902, P903? P902, P903 CHECK TROUBLE IN RL901? RL901 TROUBLE IN...
  • Page 15 10. NO TILT (NO ROTATION ) NO TILT (NO ROTATION) CHECK TROUBLE IN Q504 IC401 ( MI COM) WAVE FORM ? CHECK TROUBLE IN 15V LINE AND 6.3V LINE ? 15V LINE, 6.3V LINE CHECK TROUBLE IN Q503 EMITTER Q501~Q503 VOLTAGE ? TROUBLE IN P501, TILT COIL...
  • Page 16 11. TROUBLE IN AUDIO NO AUDIO (INPUT WAVEFORM ; 2Vp-p (NO SOUND) CHECK TROUBLE IN IC1 PIN 7, 8 JA804, P1 (AUDIO SIGNAL) ? CHECK TROUBLE IN IC2 PIN 2, 10 ? TROUBLE IN SPEAKER, P3, P4, P801, P802, JA802...
  • Page 17 < Front Control > Heater ( 6.3V ) Signal POWER H-Sync Sig Cable V-Sync Sig VIDEO VIDEO C-MIC PRE-AMP MAIN AMP C DATA(SDA) (IC302) (IC303) SELECT RIGHT C CLOCK(SCL) H/V POSITION LEFT H/V SIZE BRIGHTNESS SPPC CONTRAST 125V MICOM AUDIO CONTROL TRAPIZODE OSD IC 8V REG.

  • Page 18: Description Of Block Diagram

    DESCRIPTION OF BLOCK DIAGRAM 1. Line Filter & Associated Circuit. 5) User can adjust screen condition by each OSD This is used for suppressing noise of power input line function. The data of the adjusted condition is flowing into the monitor and/or some noise generated stored in EEPROM(IC402).
  • Page 19 14. Dynamic Focus Output Circuit. 17. Image Rotation (Tilt) Circuit. This circuit takes the horizontal and the vertical This circuit corrects the tilt of the screen by supplying parabola waves from the TDA4856(IC701) and the image rotation signal to the tilt coil which is amplifies it to maintain constant focus on center and attached near the deflection yoke of the CRT.

  • Page 21: Wiring Diagram

    WIRING DIAGRAM P201 P202 P405 P804 P803 P801 P403 P802 P501 P904 P702 SPEAKER SPEAKER S– TH901 P402 P703 P701 P805 AC Socket P704 Signal Cable P302 P301 P304 P303...
  • Page 22 EXPLODED VIEW EXPLODED VIEW PARTS LIST Ref. No. Part No. Description Q'ty Material CABINET ASS'Y, LG, S/W 77S (TCO) 3091TKC002U LGC ABS AF303G UL94-5V 3091TKC002V CABINET ASS'Y, LG, S/W 77M (MPR-II) 3551TKS012D COVER ASS'Y, GRILLE (R/L) (TCO-95) LGC ABS AF303S...

  • Page 23: Audio Board (Component Side)

    7. AUDIO BOARD (Component Side) 8. AUDIO BOARD (Solder Side)
  • Page 24 5. CONTROL BOARD (Component Side) 6. CONTROL BOARD (Solder Side)
  • Page 25 3. VIDEO BOARD (Component Side) 4. VIDEO BOARD (Solder Side)
  • Page 26 DISASSEMBLY 3. TOTAL CHASSIS ASSEMBLY REMOVAL 1. TILT/SWIVEL REMOVAL 1) Set the monitor face down. 1) Disconnect P901 (Degaussing pin), P701 2) Pressing the latch (a), carefully remove the (H-DY pin), and P601(V-DY pin). Tilt/Swivel by pulling it upward. 2) Remove two screws (a) from the Main Bracket to separate it from the Front Cabinet.
  • Page 27 5. BOTTOM BRACKET REMOVAL 6. MAIN BOARD ASSEMBLY REMOVAL 1) Remove eight screws (a). 1) Remove ten screws (a). 2) Remove the Bottom Bracket. 2) Remove three screws (b). 3) Release two latches (c) from the Main Board Assembly. Bottom Bracket...

  • Page 28: Timing Chart

    TIMING CHART VIDEO SYNC FACTORY PRESET MODE MODE MARK MODE 1 MODE 2 MODE 3 MODE 4 MODE 5 MODE 6 MODE 7 MODE 8 MODE 9 MODE 10 MODE 11 — — — — — — Sync Polarity Frequency 37.50 46.88 53.68...

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