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LG FLATRON F920BJ-AL Q Series Service Manual
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LG FLATRON F920BJ-AL Q Series Service Manual

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COLOR MONITOR
SERVICE MANUAL
CHASSIS NO. : CA-130
MODEL:
(
) **Same model for Service
CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
Website:http://biz.LGservice.com
E-mail:http://www.LGEservice.com/techsup.html
F920B
(F920BJ-AL**Q)

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Summary of Contents for LG FLATRON F920BJ-AL Q Series

  • Page 1 Website:http://biz.LGservice.com E-mail:http://www.LGEservice.com/techsup.html COLOR MONITOR SERVICE MANUAL CHASSIS NO. : CA-130 MODEL: F920B (F920BJ-AL**Q) ) **Same model for Service CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
  • Page 2 - 1 -...
  • Page 3 CONTENTS SPECIFICATIONS ........... 2 BLOCK DIAGRAM ..........14 SAFETY PRECAUTIONS ........3 DESCRIPTION OF BLOCK DIAGRAM....15 SERVICE PRECAUTIONS ........4 TROUBLESHOOTING GUIDE ......17 TIMING CHART ............7 EXPLODED VIEW..........35 DISASSEMBLY ............8 REPLACEMENT PARTS LIST .......36 ADJUSTMENT ............9 SCHEMATIC DIAGRAM .........
  • Page 4 SAFETY PRECAUTIONS SAFETY-RELATED COMPONENT WARNING! X-RADIATION There are special components used in this color monitor The only potential source of X-radiation is the picture tube. which are important for safety. These parts are marked However, when the high voltage circuitry is operating on the schematic diagram and the replacement properly there is no possibility of an X-radiation problem.
  • Page 5 SERVICING PRECAUTIONS CAUTION: Before servicing receivers covered by this 9. Use with this receiver only the test fixtures specified in service manual and its supplements and addenda, read this service manual. and follow the SAFETY PRECAUTIONS on page 3 of this CAUTION: Do not connect the test fixture ground strap publication.
  • Page 6 General Soldering Guidelines (It is not necessary to reapply acrylic coating to the 1. Use a grounded-tip, low-wattage soldering iron and areas). appropriate tip size and shape that will maintain tip "Small-Signal" Discrete Transistor temperature within the range or 500 F to 600 F. Removal/Replacement 2.
  • Page 7 At IC Connections 1. Remove the defective copper pattern with a sharp To repair a defective copper pattern at IC connections use knife. the following procedure to install a jumper wire on the Remove at least 1/4 inch of copper, to ensure that a copper pattern side of the circuit board.
  • Page 8 TIMING CHART VIDEO SYNC FACTORY PRESET MODE MODE MARK MODE 1 MODE 2 MODE 3 MODE 4 MODE 5 VESA Sync Polarity – Frequency 43.269 53.674 68.677 91.146 93.750 µs Total Period 23.112 18.631 14.561 10.971 10.666 µs Video Active Time 17.778 14.222 10.836...
  • Page 9 DISASSEMBLY 1. Carefully place the monitor on a soft cushion 4. Separate the back cover from the latch at the and stand it upright with the cabinet facing bottom of the cabinet using the jig as shown in downward. the figure. 2.
  • Page 10 ADJUSTMENT 1. Preparation for Service Adjustment 2. Adjustment by Service Hot key How to enter SVC HOT KEY GENERAL INFORMATION 1. Press Menu and OSD window will appear. 2. While OSD window is displayed, is seen on the All adjustment are thoroughly checked and corrected left bottom of OSD window.
  • Page 11 4. Distortion 10. Parallelogram Scanning frequency : All Mode (Mode 1~5) Display image : Crosshatch pattern Horizontal : 10 Row Vertical : 8 Row 11. Adjustment of white balance (Adjustment of chromaticity diagram) *(Adjustment of white balance must be made after entering Hot Key Mode and DEGAUSS.) 2.5mm, 2.5mm...
  • Page 12 11-2. Adjustment of White Balance PROCEDURE After finishing adjustment of cut off (back raster), For trained and experienced service technicians only. approve "Color(15.0) Full white pattern". Use the following procedure to correct minor color Adjust to BDRV Data = 94. purity problems: Adjust RDRV and GDRV to set chromaticity diagram at : x: 0.283 0.003...
  • Page 13 3. Adjustment Using Service software Program 2. Adjustment for White Balance and Luminance. (Adjustment Program) 1) Set the White Balance Meter. 2) Press the DEGAUSSING on the OSD menu for 1. Adjustment for Factory Mode (Preset Mode). demagnetization of the CDT. 3) Display color 0,0 pattern at Mode 4.
  • Page 14 WIRING DIAGRAM P250 P201 P401 P402 P801 P453 P451 P902 P901 P702 P910 Socket P502 Signal Cable P302 P301 P303 - 13 -...
  • Page 15 BLOCK DIAGRAM - 14 -...
  • Page 16 DESCRIPTION OF BLOCK DIAGRAM 1. Line Filter & Associated Circuit. 5. X-ray Protection. This is used for suppressing noise of power input line This circuit detects the rectified DC voltage comes flowing into the monitor and/or some noise generated from the FBT pin 4. If the high voltage of the FBT in this monitor flowing out through the power input reaches up to about 30kV (abnormal state), H.V control (IC802) detects.
  • Page 17 12. High Voltage Output & FBT (Flyback Transformer). 18. Static Convergence Control Circuit. The high voltage output circuit is used for generating This circuit corrects the convergence of the screen by pulse wave to the primary coil of the FBT (Flyback supplying the convergence signal to the 4H (STC) coil Transformer (T701)).
  • Page 18 TROUBLESHOOTING GUIDE 1. NO POWER NO POWER (POWER INDICATOR OFF) TROUBLE CHECK IN FUSE (F901) FUSE OK?(F901) SMPS Switch (ON, OFF) CHECK TROUBLE IN D901 BRIDGE DIODE? BRIDGE DIODE (D901) CHECK C905(+) VOLTAGE TROUBLE IN 145VDC at 110V input IC901, Q901 310VDC at 220V input IC901, Q901 CHECK...
  • Page 19 2. NO CHARACTER NO CHARACTER TROUBLE IN CHECK P301, SIGNAL CABLE, FUSE OK?(F901) PC SIGNAL CHECK TROUBLE IN IC302 PIN 1, 19, 20, 21, 27, 28 IC302, P302 PIN 10 (5V) ? CHECK IC303 PIN 1, 3, 5 TROUBLE IN PIN10 (12V), IC303 PIN 6 (80V) ?
  • Page 20 3. NO RASTER NO VIDEO (POWER INDICATOR GREEN or AMBER) CHECK AMBER TROUBLE IN POWER INDICATOR P302 SIGNAL CABLE GREEN or AMBER ? GREEN CHECK ROTATE SCREEN CONTROL SCREEN CONTROL KNOB TO CLOCKWISE KNOB OF FBT or COUNTER CLOCKWIES CHECK VOLTAGE AT D924/D926 CATHODE (190V) TROUBLE IN PRIMARY...
  • Page 21 4. NO VERTICAL DEFLECTION NO V-DEFLECTION (ONE HORIZONTAL LINE) CHECK TROUBLE IN IC601 Pin 3 (15V) ? T901 15V Line CHECK TROUBLE IN IC601 PIN 7 (47V)? T701 47V line CHECK TROUBLE IN IC801 PIN 12, 13 IC801 (SAWTOOTH WAVE)? TROUBLE IN IC601, V-CIRCUIT Waveforms...
  • Page 22 5. TROUBLE IN DPM Stand-by/SUSPEND/ DPMS OFF MODE FAILURE CHECK CHECK PC, INPUT H/V SYNC SIGNAL IC401 (MICOM) (PC IS NOT GOING INTO DPM PIN 40, 41 (H/V INPUT) MODE) SIGNAL? NO H/V SYNC SIGNAL CHECK TROUBLE IN IC401 PIN 9, 8 X401, IC401 WAVEFORM? CHECK...
  • Page 23 6. NO DEGAUSSING NO DEGAUSSING CHECK TROUBLE IN IC401 PIN 6 (5V)? IC401 (MICOM) CHECK TROUBLE IN Q920 COLLECTOR D925 VOLTAGE (0.5V)? CHECK TROUBLE IN P901? P901 TROUBLE IN CHECK RL901 RL901? TROUBLE IN TH901, DEGAUSSING COIL - 22 -...
  • Page 24 7. H_Deflection Failure 1. Appear the Voltage 15VDC at IC802 Pin 7 replace R838. Q802 Pin 6 waveform is 2. Check IC801 Pins 7~10, 7~6. right? 3. Replace IC402. Q833drain Check Q806, Q807 waveform is right? ZD802, D831. Q832 drain Check Q802, Q803 waveforms are right? Check -12V line.
  • Page 25 8. S Correction Failure Check S1 ~ S5 signal. Refer to the S-corrction table page? S1~S5 signals are right at Check and replace IC401. each frequency block? Check and replace C833, C854 ~ C859, Q811, Q812, Q836 ~ Q839, Q841~Q844 9.
  • Page 26 11. Abnormal H_Size The Voltage Repeat the troubleshooting waveforms Q801 Collector Guide of H_deflection failure. are right? 7 T701 pin 1 Replace T701. wareform is right? Check IC802 and around. 12. Side Pin or Trap Failure Check if AC Voltage of IC801 Pin 11 Check and replace IC801,IC401.
  • Page 27 14. Tilt Failure Check tilt connector connection IC401 Pin 3 output duty varies with Check and replace IC401. different DAC values? IC702 Pin 1 output varies Check and replace IC702. with different DAC values? Check and replace CRT. 15. V Size or Pos. Variation Failure IC801 Pin 12, 13 Check some parts around IC801.
  • Page 28 16. High Voltage Failure Q704 gate Check +15 V line. driving pulse exist? ICheck and replace The waveform is right? Q705, Q706, Q707, R710, IC802. Are there some voltages Check and replace (80V, 47V, 160V, etc) Q704, D706, D704 at secondary part of FBT? Done.
  • Page 29 18. Focus Failure IC801 Pin 32 Check and replace IC801. output are right? Some parts around Replace failed part. Q721, Q723, Q724 and Q725 are right? Some parts around T701 Replace failed part. are right? Check the connection between FBT Pin 13, CRT Socket PCB.
  • Page 30 19. Micom Failure IC401 Pin 6 input is over Check IC903. 4.2V? IC401 Pin 8 and 9 Check X401, C406 and C407. inputs are right? Check and replace IC401 Pin 5 input is R443,C730 High Active? All in/output values are Replace IC401.
  • Page 31 21. User Control Failure Check connector Ass’y. IC401 Pins 21 and 22 Check and replace function key. inputs are right at each function? Check and replace IC401. Done. 22. Missing Color Proper Video levels are Check signal generator and on P301 Pin 1, 3 and 5. signal cable.
  • Page 32 23. Visible Retrace Check white balance adjustment. G2 voltage is right? Check G2 control volume and FBT. Blank pedestal is on Check IC302 Pin 19, 20 and 21 of IC302 and related components. Check R775, P302 Assy, Is V_FLB and DC_bias on Q771, D771 and D772 G1 Pin at CRT socket? Done.
  • Page 33 25. Misconvergence Check P451 Assy. Proper voltage are Check and replace Q451, Q452, appeared on P451 Q453 Pin 4, 6 Change CRT and readjust convergence. Done. 26. Poor Focus Adjust focus VR. Aging monitor and Improved focus? check for focus change. Check focus leads from FBT to CRT Socket.
  • Page 34 27. Purity Failure Degaussing Purity is right? Done. Degaussing circuit is right? Refer to 6 NO Degaussing. Replace CRT and verify purity. - 33 -...
  • Page 35 - 34 -...
  • Page 36 Ref. No. Part No. Description 3091TKC118A CABINET ASSEMBLY, F920 BRAND C091 3RD FLATRON TCO99 6318L19008A CDT(CIRC), M46QDG423X11NDDD LG-PHILIPS 107KHZ 29.1MM FLATRON TCO V2 3809TKC045L BACK COVER ASSEMBLY, F920BJ C044 PC+ABS 8D650 TCO03 3043TKK101G TILT SWIVEL ASSEMBLY, F920BJ B059/T064 8D650 KUMI 339-002J...
  • Page 37 REPLACEMENT PARTS LIST CAUTION: BEFORE REPLACING ANY OF THESE COMPONENTS, READ CAREFULLY THE SAFETY PRECAUTIONS IN THIS MANUAL. * NOTE SAFETY Mark AL ALTERNATIVE PARTS DATE: 2004. 3. 30. DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION *S *AL LOC.
  • Page 38 DATE: 2004. 3. 30. DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION DIODEs C833 181-482D 184J 18.0*15.0*8.5*7.5 250V C834 0CN1040K949 0.1M 50V Z F TA52 D301 0DS141489AB 1N4148 TP GRANDE DO-34 500MW C835...
  • Page 39 0.22UH K 2.3*3.4 TP Q726 0TR555109AB 2N5551 TP SAMSUNG TO92 AMP L302 0LA0150K119 AXIAL TAE YANG 0.15UH 10% A Q771 0TR920009AB KSP92 TP SAMSUNG TO92 HIGH V L303 0LA0220K119 0.22UH K 2.3*3.4 TP Q801 0TR558900BA "2SC5589(LG,W/M) BK TOSHIBA T" - 38 -...
  • Page 40 DATE: 2004. 3. 30. DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION Q802 0TR471009AA KSD471AC-Y TP SAMSUNG TO92 R401 0RD3300Q609 330 1/4W(3 5% TA52 Q803 0TR564009AB KSB564AC-YTA TP SANSUNG TO92 R402 0RD1000Q609...
  • Page 41 DATE: 2004. 3. 30. DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION R705 0RB0150K609 0.15 OHM 2 W 5% TA52 R818 0RD2701Q609 2.70K 1/4W(3 5% TA52 R706 0RD1003Q609 100K 1/4W(3 5% TA52...
  • Page 42 DATE: 2004. 3. 30. DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION R920 0RD0432Q609 43 OHM 1/4 W (3.4) 5% TA52 R207 0RD3300Q609 330 1/4W(3 5% TA52 R921 0RD0332Q609 33 1/4W(3 5% TA52...
  • Page 43 DATE: 2004. 3. 30. *S *AL LOC. NO. PART NO. DESCRIPTION / SPECIFICATION R829 0RH1002D622 10K OHM 1 / 10 W 2012 5.00% R830 0RH1002D622 10K OHM 1 / 10 W 2012 5.00% R835 0RH1003D622 100K 1/10W 5 D.R/TP R836 0RH1004D622 1.0M 1/10W 5 D.R/TP R837...
  • Page 44 SCHEMATIC DIAGRAM WF 31 WF 29 WF 28 WF 26 WF 27 WF 03 WF 32 WF 04 WF 30 WF 16 WF 17 WF 15 WF 20 WF 24 WF 19 WF 18 WF 23 WF 01 WF 33 WF 02 WF 25 WF 14...
  • Page 45 Mar. 2004 P/NO : 3828TSL087F Printed in Korea...

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