LG FLATRON F720BL Service Manual Download Page 31 | Manualshive

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background image

Some parts around T701

are right?

IC401 Pin 24

output are right?

Q710 and parts around

are right?

18. Focus Failure

NO

NO

NO

Check the connection between

FBT Pin 12,

CRT Socket PCB.

Check and replace IC401.

Replace failed part.

Replace failed part.

YES

YES

YES

22

23

Waveforms

- 30 -

IC401, #24 FBT, #12

22

23

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Summary of Contents for FLATRON F720BL

Page 1: ...0 g Inside Snow white paper 100 g 4 Printing Method 5 Bindery Saddle stitch 6 Language English 7 Number of pages 45 Part No 1 2 Service Guide Specification Service Guide Specification Changes 4 REV NO MM DD YY CHANGE NO CHANGE CONTENTS 1 2 3 4 5 7 6 SUFFIX F720BL KLEUED LG 3828TSL105D 8 Special Instructions 3 Product Name FLATRON F720B FAN Y Y YEO H M 2004 08 07 2004 08 07 ...

Page 2: ...z LGservice com E mail http www LGEservice com techsup html CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL MODEL F720B F720BL AL E CHASSIS NO CA 136 Same model for SVC Same looking with new chassis Issue Date 2003 12 ...

Page 3: ...Format Refer to the Timing Chart 2 3 Signal Connector 3 row 15 pin Connector Attached 2 4 Scanning Frequency Horizontal 30 71 kHz Vertical 50 160 Hz 3 POWER SUPPLY 3 1 Power Range AC 100 240V 50 60Hz 1 0A Max 3 2 Power Consumption 4 DISPLAY AREA 4 1 Active Video Area Max Image Size 325 4 x 244 1 mm 12 81 x 9 61 Preset Image Size 310 x 230 mm 12 20 x 9 06 4 2 Display Color Full Colors 4 3 Display R...

Page 4: ...joints frayed leads damaged insulation solder splashes or the sharp points Be sure to remove all foreign materials IMPLOSION PROTECTION All used display tubes are equipped with an integral implosion protection system but care should be taken to avoid damage and scratching during installation Use only same type display tubes X RADIATION The only potential source of X radiation is the picture tube H...

Page 5: ...st receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead Always remove the test receiver ground lead last 9 Use with this receiver only the test fixtures specified in this service manual CAUTION Do not connect the test fixture ground strap to any heat sink in this receiver Electrostatically Sensitive ES Devices Some semiconductor solid state devices ...

Page 6: ...tip as the solder melts 2 Draw away the melted solder with an anti static suction type solder removal device or with solder braid before removing the IC Replacement 1 Carefully insert the replacement IC in the circuit board 2 Carefully bend each IC lead against the circuit foil pad and solder it 3 Clean the soldered areas with a small wire bristle brush It is not necessary to reapply acrylic coati...

Page 7: ...onnection 4 Route the jumper wire along the path of the out away copper pattern and let it overlap the previously scraped end of the good copper pattern Solder the overlapped area and clip off any excess jumper wire At Other Connections Use the following technique to repair the defective copper pattern at connections other than IC Pins This technique involves the installation of a jumper wire on t...

Page 8: ...1 1 14 2 70 0 57 V 85 07 11 755 11 178 0 577 0 056 0 503 0 018 H 68 677 14 561 10 836 3 725 1 016 2 201 0 508 V 85 00 11 764 11 182 0 582 0 044 0 524 0 014 Mode H V Sort 1 2 3 4 640x480 75Hz 800x600 85Hz 1024x768 85Hz 800x600 75Hz Dot Clock MHz Horizontal Frequency kHz Vertical Frequency Hz Horizontal etc µs Vertical etc ms Sync Polarity Frequency Total Period A Video Active Time B Sync Duration E...

Page 9: ...parate the back cover from the latch at the bottom of the cabinet using the jig as shown in the figure Insert the jig into the latch and lift slightly 3 Separate the back cover from the latch on top of the cabinet using a screwdriver as shown in the figure Insert the screwdriver and gently press the latch 5 Lift up the back cover to separate from cabinet assembly ...

Page 10: ...x position 1 Adjustment for B Voltage 1 Display cross hatch pattern at Mode 4 2 Check D961 cathode voltage within 50V 1V 2 Adjustment for High Voltage 1 Display cross hatch pattern at Mode 4 2 Enter the SVC SUB menu as the following instruction 3 Adjust H Voltage to 25 8kV 0 1 kV by adjust 1 P value 2 Adjustment by Service Hot key How to enter SVC HOT KEY 1 Press Menu and OSD window will appear 2 ...

Page 11: ...0 Contrast Maximum Brightness Maximum Color temperature 9300K 11 1 Adjustment of cut off Adjustment of back raster 11 1 a Before adjustment press Menu and Degauss to remove Enter hot key mode Adjust Brightness and Contrast to Max in OSD window 1 Adjust cut off back raster first Enter DEGAUSS in the Menu and modify the following data Modify RCUT to Min Modify GCUT To Min Adjust to BCUT Data 127 7F ...

Page 12: ...5Hz 69kHz 85Hz Display image White flat field Luminance Cut off point at the center of the display area Note Color purity adjustments should only be attempted by qualified personnel PROCEDURE For trained and experienced service technicians only Use the following procedure to correct minor color purity problems 1 Make sure the display is not affected by external magnetic fields 2 Very carefully bre...

Page 13: ... above from number 6 to 16 20 COMMAND PRESET EXIT Y Yes command 2 Adjustment for White Balance and Luminance 1 Set the White Balance Meter 2 Press the DEGAUSSING on the OSD menu for demagnetization of the CDT 3 Display color 0 0 pattern at Mode 4 4 COMMAND PRESET START Y Yes command 5 Set Bightness and Contrast to max position 6 COLOR ADJ LUMINANCE command of the alignment program 7 COLOR ADJ BIAS...

Page 14: ...itor only 1 Port Setup a Copy UserPort sys file to c WINNT system32 drivers folder b Run Userport exe c Remove all default number d Add 300 3FF e Click Start button f Click Exit button 2 EDID Read Write 1 Run WinEDID exe 2 Edit Week of Manufacture Year of Manufacture Serial Number a Input User Info Data b Click Update button c Click Write button Adjustment and EDID Data Down in GCSC ...

Page 15: ... 6D 44 43 01 01 01 01 01 0E 01 03 18 21 19 B9 EA 9A D9 A1 54 4B 99 24 12 48 4C FF FE 80 31 59 71 4F 45 59 61 59 81 80 81 4A 01 01 01 01 EA 24 00 60 41 00 28 30 30 60 13 00 36 E6 10 00 00 1E 30 2A 00 98 51 00 2A 40 30 70 13 00 36 E6 10 00 00 1E 00 00 00 FD 00 32 A0 1E 47 0B 00 0A 20 20 20 20 20 20 00 00 00 FC 00 46 37 30 30 42 0A 20 20 20 20 20 20 20 00 EDIDDataEdit UsingServicesoftwareProgram 1Rea...

Page 16: ...WIRING DIAGRAM 15 P501 P201 P405 P301 P302 G2 P702 P701 T1 P402 P902 S S Signal Cable AC Socket FBT ...

Page 17: ...ircuit Dynamic FOCUS Circuit Brightness Control 160V 40V 13V D D Feed Back 13V SCL SDA H Sync V Sync PWM Control Signal 13V 50V DY CDT Heater 6 3V I 2 C Screen H V R G B Bias H Drive B Drive B 13V DPM Control Circuit 5V 6 3V 8V 80V Voltage feedback Degaussing Coil Dynamic Focus Static Focus TILT Coil 50V 80V 5V G2 G1 Auto Beam Limit DC DC Converter FBT T701 Regulation Circuit 13V SMPS T901 5V BRIG...

Page 18: ...C401 discriminates the operating mode fromthe sync polarity and resolution 3 After microprocessor reads these adjusted mode data storedat EEPROM it controls operating mode data through IIC 4 Users can control screen condition by the OSD Select Up Down Left Right Exit 5 D D Converter Circuit To obtain constant high voltage this circuit supplies controlled DC voltage for FBT and horizontal deflectio...

Page 19: ...mplifies the video signal which comes from the video pre amp circuit and amplified it to applied the CDT cathode 14 Video Processor Circuit Video processor circuit consists of the video drive output block The video drive IC IC302 receives the video signal from PC The gain of each channel is controlled by MICOM through IIC The cut off circuit compensate different voltage of each channel between the...

Page 20: ...D941 D942 D906 CHECK FUSE OK F901 19 TROUBLESHOOTING GUIDE 1 NO POWER NO POWER POWER INDICATOR OFF NO NO NO NO TROUBLE IN Q951 Q952 Q941 Q942 TROUBLE IN FUSE F901 SMPS Switch ON OFF Waveforms TROUBLE IN BRIDGE DIODE D900 TROUBLE IN IC901 Q901 TROUBLE IN D971 D961 D951 D904 D941 D942 D906 YES YES YES YES Q901 Drain IC901 6 2 1 ...

Page 21: ...LE IN IC302 P301 TROUBLE IN IC303 TROUBLE IN IC304 YES YES YES YES CHECK IC302 PIN 5 6 7 CHECK IC302 PIN 1 24 23 19 20 21 PIN 18 5V CHECK IC303 PIN 1 2 3 PIN8 8V PIN 4 80V CHECK R G B CATHODE VOLTAGE Waveforms 28 27 30 31 20 IC302 5 6 7 IC302 23 IC302 19 20 21 IC302 1 IC302 24 CDT RK GK BK 26 27 28 29 30 31 29 ...

Page 22: ...8 PIN20 PIN21 CHECK POWER INDICATOR GREEN or FLASH 21 3 NO RASTER FLASH NO NO NO TROUBLE IN IC401 MICOM TROUBLE IN P302 SIGNAL CABLE ROTATE SCREEN CONTROL KNOB TO CLOCKWISE or COUNTER CLOCKWIES TROUBLE IN PRIMARY CIRCUIT OF T901 TROUBLE IN CDT SOCKET BOARD GREEN YES YES YES NO VIDEO POWER INDICATOR GREEN or FLASH IC401 18 IC401 20 IC401 21 14 7 5 5 14 7 Waveforms ...

Page 23: ...WTOOTH WAVE CHECK IC601 Pin 3 13V 22 4 NO VERTICAL DEFLECTION NO V DEFLECTION ONE HORIZONTAL LINE NO NO NO TROUBLE IN IC601 V CIRCUIT TROUBLE IN T901 13V Line TROUBLE IN T701 40V line TROUBLE IN IC401 YES YES YES 9 8 Waveforms IC401 33 IC401 34 8 9 ...

Page 24: ...SIGNAL NO NO NO TROUBLE IN T901 or PC CHECK PC PC IS NOT GOING INTO DPM MODE TROUBLE IN X401 IC401 TROUBLE IN IC401 TROUBLE IN IC401 NO TROUBLE IN Q941 Q951 NO H V SYNC SIGNAL YES YES YES YES DPMS TABLE NORMAR ON ON NORMAL GREEN STAND BY OFF ON OFF 0V FLASH SUSPEND ON OFF OFF 0V FLASH OFF OFF OFF OFF 0V FLASH H V SYNC VIDEO LED MODE ITEM 3 4 C401 45 IC401 46 CHECK IC401 PIN 16 5V HIGH 4 3 Waveform...

Page 25: ...VOLTAGE 0 5V CHECK P902 CHECK RL901 CHECK IC401 PIN 4 5V 6 NO DEGAUSSING NO DEGAUSSING NO NO NO NO TROUBLE IN TH901 DEGAUSSING COIL TROUBLE IN IC401 MICOM TROUBLE IN D953 TROUBLE IN P902 TROUBLE IN RL901 YES YES YES YES 24 ...

Page 26: ...heck IC401 Pins 39 40 41 2 Replace IC401 Check Q720 50V LINE D710 Check Q704 Check 13V line Check and replace T703 and Q706 Check DY connector connection YES YES YES 5 18 19 21 20 Waveforms 8 Invariable H_Size NO Check and replace IC401 Check if DC voltage of IC401 PIN 35 wave is Variable 6 5 18 20 21 19 IC401 18 Q706 Base Q706 Collector Q719 Drain Q705 Drain IC401 35 6 ...

Page 27: ...ROUBLE IN IC401 MICOM TROUBLE IN Q711 Q716 TROUBLE IN L703 TROUBLE IN C722 C723 C726 C729 NO NO NO YES YES YES Cs SIGNAL TABLE HORIZONTAL FREQUENCY fH 30K 33 9K 34K 38 9K 39K 43 9K 44K 48 9K 49K 51 9K 52K 57 9K 58K 61 9K 62K 65 9K 66K 71K Cs1 L L H H H H H H H Cs3 L H L H L L L H H Cs2 L L L L H H H H H ...

Page 28: ...eform Q706 Collector is right 27 11 Abnormal H_Size NO NO Repeat the troubleshooting Guide of H_deflection failure Check D D converter circuit Check IC401 B control circuit YES 12 Side Pin or Trap Failure NO 13 Para or Pin Balance Failure Replace IC401 Check and replace IC401 21 6 Q706 Collector IC401 35 21 6 Waveforms ...

Page 29: ...Pin 26 output duty varies with different DAC values 14 Tilt Failure Check tilt connector connection Check and replace CRT NO NO Check and replace IC401 Check Q503 Q501 Q502 YES YES 15 V Size or Pos Variation Failure Check and replace IC401 and IC601 NO Check some parts around IC401 YES 28 8 9 IC401 33 IC401 34 Waveforms ...

Page 30: ...ion failure YES YES 17 ABL Failure YES NO Check and replace CRT Input full white pattern to monitor Check P302 D801 R801 803 R798 Check and replace IC302 Check and replace T701 NO YES 29 Q719 Drain Q706 Collector IC302 Pin22 input exists and varies with different patterns T701 Pin 6 Voltage exists 18 Waveforms 21 18 21 YES waveform is right Q719 drain ...

Page 31: ... output are right Q710 and parts around are right 18 Focus Failure NO NO NO Check the connection between FBT Pin 12 CRT Socket PCB Check and replace IC401 Replace failed part Replace failed part YES YES YES 22 23 Waveforms 30 IC401 24 FBT 12 22 23 ...

Page 32: ... right IC401 Pin 45 and 46 inputs are right IC401 Pin 16 input is over 4 2V 19 Micom Failure 20 OSD Failure NO NO NO NO Done Change IC302 Check Q903 D908 ZD902 Check X401 Check and replace R451 C408 Replace IC401 YES YES YES YES 3 4 31 IC401 45 IC401 46 Waveforms ...

Page 33: ...d replace IC401 Check and replace function key YES 22 Missing Color NO Change the CRT Check signal generator and signal cable NO Refer to 2 No Charcter NO Check and replace IC303 and IC304 NO Check C341 C346 and G2 wire Check around FBT circuits also YES YES YES YES 32 Proper AC voltage are on all cathodes Proper DC voltage are on all cathodes G2 voltage is right ...

Page 34: ...ible Retrace Check white balance adjustment NO NO NO Done Check G2 control volume and FBT Check IC302 and related components Check Q799 and related components YES YES YES 33 Degaussing circuit is right Purity is right 24 Purity Failure Degaussing YES NO Replace CRT and verify purity Done Refer to 6 NO Degaussing NO YES ...

Page 35: ...Done Change CRT and readjust convergence Yes Done No 26 Poor Focus Adjust focus VR Check focus leads from FBT to CRT Socket Check the CRT Socket YES Aging monitor and check for focus change NO Refer to 18 Dynamic Focus Failure NO Replace the CRT and verify focus YES 34 Dynamic focus circuit is right ...

Page 36: ... 35 EXPLODED VIEW 2 5 6 12 11 11 B A 8 9 10 13 13 1 16 15 14 3 4 7 a b c b ...

Page 37: ... 29 1MM FLATRON TCO RTC BACK COVER ASSEMBLY F720BK 041 NT For USA Russia TILT SWIVEL ASSEMBLY F720 FLATRON 058 060 NT SCREW ASSY PHP 5 20 FZMY GW18 NEW TYPE COIL DEGAUSSING 14OHM 0 5MM 110T 17 F700BJ W O PURITY PWB PCB ASSEMBLY SUB F720BL CONTROL TOTAL BRAND CA 136 FBT FLY BACK TRANSFORMER C93 BSC25 1458 FUJIAN FURI HITACHI 17 70KHZ FLAT SOCKET CIRC POWER CDJ 3C DUOLING AC UNIVERSAL 3PIN BLACK SOC...

Page 38: ...CK2220K515 2200P 50V K B TS C416 0CQ1031N409 0 01U 100V J POLY TP C417 0CK1040K945 0 1UF 50V Z F TR C419 0CQ2221N409 2200PF 100V J PE TP C420 0CQ6831N509 0 068U 100V K POLY TP C421 0CK1020K515 1000PF 50V K B TR C422 0CK2220K515 2200P 50V K B TS C423 0CK2220K515 2200P 50V K B TS C424 0CE475CK638 4 7UF SHL SD 50V M FM5 TP 5 C426 0CK4710K515 470PF 50V K B TR C427 0CK4710K515 470PF 50V K B TR C501 0CE...

Page 39: ...0V 75VA 2000MA 4NSEC 0 025UA D501 0DSPT00029A 1N4148M PCTRONIX TP DO34 100V 75VA 2000MA 4NSEC 0 025UA D702 0DRGF00120A MUR460 15MM GULF BK DO201AD 600V 4A 150A 45NSSEC 10UA D703 0DRGF00120A MUR460 15MM GULF BK DO201AD 600V 4A 150A 45NSSEC 10UA D704 0DRFC00300A FFPF04U150S FAIR CHILD BK TO220F 1500V 4A 40A 150NSSEC 7UA D705 0DRTW00089A SRT14 1021 TIWAN SEMI TP NON 40V 1A 25A SEC 0 5MA D706 0DRFC003...

Page 40: ... TO220F 200V 9 5A Q720 0TR390409CA FAIRCHILD 2N3904 TA TP TO 92 60V 0 2A Q799 0TRKE90019A MPSA92 KEC TP TO92 300V 500MA Q821 0TR320509AB KTC3205 Y KTC2236A TP KEC TO92L NPN Q901 0TF760000AD SSS7N60B FAIRCHILD ST TO220F 650V 7A Q903 0TR100809AA KSC1008C Y TP SAMSUNG TO92 NPN Q941 0TR319809AA KTC3198 Y KTC1815 TP KEC TO92 NPN Q942 0TR127309AA KTA1273 Y KTA966A TP KEC TO92L PNP Q951 0TR319809AA KTC31...

Page 41: ... TA62 R745 0RD4702Q609 47K 1 4W 3 5 TA52 R746 0RD2201Q609 2 20K 1 4W 3 5 TA52 R747 0RD3001Q609 3K 1 4W 3 5 TA52 R748 0RD4702Q609 47K 1 4W 3 5 TA52 R749 0RD2201Q609 2 20K 1 4W 3 5 TA52 R750 0RD3001Q609 3K 1 4W 3 5 TA52 R751 0RD0222A609 22 OHM 1 2 W 7 0 5 TA52 R752 0RD2201Q609 2 20K 1 4W 3 5 TA52 R753 0RD3001Q609 3K 1 4W 3 5 TA52 R754 0RD6800A609 680 OHM 1 2 W 7 0 5 TA52 R756 0RD2202A609 22K OHM 1 2...

Page 42: ...1280F6 JEIL 12V DC 1MA VERTICAL 7MM SW207 6600R00001A JTP1280F6 JEIL 12V DC 1MA VERTICAL 7MM T1 6631T11005D 1 W T 480MM UL 1015 AWG 22 CB775C T701 6174T11006C C93 BSC25 1458 FUJIAN FURI HITACHI 17 70KHZ FLAT T702 6170TCZ013A EI2218 26UH D FOCUS FB775G T703 6170TCZ015A EI 19 4 45MH H DRIVE 700BJ T901 6170TMZ153A EER3435 300UH V 16PIN T710BL SI SC NY JS TC 71 85KHZ TH901 6322B00002D MZ72 4 5RN290V G...

Page 43: ...0 21 19 IC401 18 Q706 Base Q706 Collector Q719 Drain Q705 Drain IC401 35 22 23 IC401 24 FBT 12 IC401 20 IC401 21 14 IC302 5 6 7 IC302 23 IC302 19 20 21 IC302 1 IC302 24 CDT RK GK BK 26 27 28 29 30 31 11 16 17 15 2 WF1 WF1 WF2 WF29 WF28 WF27 WF26 WF30 WF31 WF16 WF17 WF23 WF18 WF21 WF20 WF19 WF15 WF8 WF9 WF6 WF11 WF10 WF3 WF4 WF5 WF14 WF 7 WF22 ...

Page 44: ... O B T I U C R I C D E T N I R P e d i S t n e n o p m o C D R A O B L O R T N O C 1 e d i S r e d l o S D R A O B L O R T N O C 2 e d i S t n e n o p m o C D R A O B N I A M 3 e d i S r e d l o S D R A O B N I A M 4 ...

Page 45: ...Dec 2003 P NO 3828TSL105D Printed in China ...

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