LG CD-372A Service Manual Download Page 8 | Manualshive

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- 2-3 -

(1) If display LCD lighting is abnormal

Is the function selector in

the CD position?

Do display LCD then light?

Check voltage in the power
supply circuitry.

(WITHOUT DISC)

• X701 defective.

• Reset circuit defective.
• Surrounding circuit

defective.

• Power supply circuitry

defective

• Check Q516 and CN603

Is IC201 Pin51 52 53 54 to
72 output waveform normal?

Is µ-COM reset circuit
nomail
micom
VDD

Is µ-COM 701pin14 and 15
(OSC) input?

• Pattern defective.

• Display defective.

NO

NO

NO

NO

NO

YES

RESET 0V

0V

3V

3V

3V

About 0.125 µsec

CD FUNCTION

YES

YES

YES

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Summary of Contents for CD-372A

Page 1: ...N 2 ELECTRICAL SECTION ADJUSTMENT 2 1 TROUBLESHOOTING GUDIE 2 2 INTERNAL BLOCK DIAGRAM OF IC s 2 11 IC VOLTAGE SHEET 2 16 BLOCK DIAGRAM 2 20 SCHEMATIC DIAGRAMS 2 22 WIRING DIAGRAMS 2 36 PRINTED CIRCUIT BOARD DIARGAMS 2 38 SECTION 3 EXPLODED VIEWS 3 1 SECTION 4 REPLACEMENT PARTS LIST 4 1 CONTENTS ...

Page 2: ...eams may damage the eyes Absolutely never permit laser beams to enter the eyes Also NEVER switch ON the power to the laser output part lens etc of the pick up if it is damaged 5 Cleaning the lens surface If there is dust on the lens surface the dust should be cleaned away by using an air bush such as used for camera lens The lens is held by a delicate spring When cleaning the lens surface therefor...

Page 3: ...acing a component part first disconnect the power supply lead wire from the unit 2 All equipment measuring instruments and tools must be grounded 3 The workbench should be covered with a conductive sheet and grounded When removing the laser pick up from its conductive bag do not place the pick up on the bag This is because there is the possibility of damage by static electricity 4 To prevent AC le...

Page 4: ...es sufficient to damage ESD devices 5 Do not use freon propelled chemicals These can generate electrical charges sufficient to damage ESD devices 6 Do not remove a replacement ESD device from its protective package until immediately before you are ready to install it Most replacement ESD devices are packaged with leads electrically shorted together by conductive foam aluminum foil or comparable co...

Page 5: ... 1 5 SPECIFICATIONS Designs and specifications are subject to change without notice for improvement ...

Page 6: ...z 1404 1400 kHz TC101 Maximum 5 Repeat steps 3 and 4 for several times 2 FM ADJUSTMENT STEP ITEM SSG OUTPUT SET FREQUENCY ADJUSTMENT ADJUST FOR 1 VT 108MHz L102 5 0V 2 SENSITIVITY 90MHz 90MHz L101 Maximum 3 TAPE DECK ADJUSTMENT DECK MODE TEST TAPE TEST POINT ADJUSTMENT ADJUST FOR BLAY BACK MTT 114 L R Output Azimuth adjusting screw L R Maximum 4 RECORD BIAS ADJUSTMENT DECK MODE TEST TAPE TEST POIN...

Page 7: ...ed Check laser circuitry Check focusing circuitry Check tracking servo circuitry Check Audio circuitry Check disc Is the function selector in the CD position Is power turned ON Does initial Reading occur OK END NO NO NO NO YES YES YES YES YES TROUBLESHOOTING GUIDE 1 CD PART CD CIRCUIT ...

Page 8: ...C X701 defective Reset circuit defective Surrounding circuit defective Power supply circuitry defective Check Q516 and CN603 Is IC201 Pin51 52 53 54 to 72 output waveform normal Is µ COM reset circuit nomail micom VDD Is µ COM 701pin14 and 15 OSC input Pattern defective Display defective NO NO NO NO NO YES RESET 0V 0V 3V 3V 3V About 0 125 µsec CD FUNCTION YES YES YES ...

Page 9: ...Connector defective IC 601 defective Dose IC601 pin20 LOCK as figure Is HF wave form output IC601 pin 2 Is tracking servo operating Is the lower IC601 pin2 waveform flat Is signal output at IC601 pin29 Is rotation normal Is there any irregularity in frequency Is HF signal normal without dropout Disc initial reading damaged defective Pick up defective Dose laser light Is signal output at tracking o...

Page 10: ...wer source returned to the Q601 Q601 collector voltage about 1 8V Flow laser current Both voltage of R610 is about 0 7V R610 0 7V R610 0 7V Laser defective connector defective short etc Q601 defective connector defective Laser defective Connector defective IC601 defective Surrounding Circuitry defective connector defective IC602 defective IC603 defective Has Pick up returned to the innermost posit...

Page 11: ...e height error Laser diode degraded IC 601 defective Pattern defective Is Fok signal output IC101 Pin2 0 4V over OK Is Fok signal input to IC601 Pin13 The waveform of IC601 pin2 Is below figure Is IC601 pin2 signal waveform output Is signal output at focus search terminal Is signal output at IC601 1 2 NO NO NO NO NO Amplitude 0 5 1 5V NO NO YES YES YES YES YES YES YES B C ...

Page 12: ...and IC701 When Fok focus Servo Conform by FEO signal IC 601 defective Is FEO signal output at IC601 Pin31 Is SMDS signal output by IC602 Pin13 Is SMPD signal output by IC602 Pin12 Has voltage at disc motor IC601 603 defective Surrounding circuitry defective Disc Motor defective Connector defective YES YES YES YES YES At start NO NO NO NO FEO ...

Page 13: ...he function selector In the TUNER position Is u com reset circuit normal Is u com IC701 17 pin and 18 OSC input IC 701 51 52 53 output Wave Form Normal 2 LCD PART LCD CIRCUIT If display LCD lighting is abnormal ...

Page 14: ...d Q503 Check Fuse F501 F502 Is there a DC voltage at the terminal of D501 D504 Replace D501 D504 Replace PN 501 TUNER ABNORMAL Is B applied to R137 141 Check IC101 102 Check Q510 511 Is there a DC Voltage at the Q517 518 Replace IC101 YES YES YES YES NO NO NO NO 3 MAIN PART MAIN CIRCUIT ...

Page 15: ...applied to Q504 Is DECK LEAF SW normal Check PN402 Replace LEAF SW Check SW402 Is there a DC voltage at the Collector terminal of Q504 Replace Q504 TAPE REC ABNOMAL Is oscillation of L401 normal Check S401 and Q402 Replace L401 YES YES YES YES NO NO NO ...

Page 16: ... 2 11 INTERNAL BLOCK DIAGRAM OF ICs LC72131 Block Diagram Pin Assignments Top View ...

Page 17: ... 2 12 Pin Assignments Top View TDA7440D Block Diagram ...

Page 18: ... 2 13 S3C8248 Block Diagram Pin Assignments Top View ...

Page 19: ... 2 14 TA2149BN Block Diagram KIA8207K TA8207K Block Diagram ...

Page 20: ... 2 15 TDA2104 MP3 DECODER Block Diagram Pin Assignments Top View ...

Page 21: ...5 16 17 18 19 20 21 22 23 24 1 7 2 3 1 7 0 1 7 3 3 1 6 0 9 1 7 1 7 1 7 0 3 3 0 0 3 3 3 3 1 7 1 2 3 4 1 7 1 7 1 7 2 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 1 7 1 8 1 7 1 7 1 7 1 6 1 6 0 1 7 1 7 1 7 1 7 1 9 0 2 1 8 1 8 1 7 1 7 1 7 2 2 0 9 1 1 1 7 2 7 IC601 CD MODE Unit V 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 0 1 4 0 3 4 3 4 1 6 1 7 0 2 1 8 3 4...

Page 22: ...1 6 1 6 1 6 1 6 1 6 1 6 1 6 1 6 3 1 0 IC701 ALL MODE Unit V E C B 8 1 8 1 7 4 Q516 CD MODE E C B 0 0 7 Q401 TAPE MODE E C B 0 0 0 7 Q351 ALL MODE E C B 0 0 0 Q402 TAPE MODE E C B 0 0 0 7 Q352 ALL MODE E C B 0 7 15 8 0 8 Q510 ALL MODE E C B 15 9 8 2 16 6 Q511 ALL MODE E C B 11 2 14 6 11 8 Q508 ALL MODE E C B 0 11 2 3 3 Q510 ALL MODE E C B 0 0 0 7 Q505 TAPE MODE E C B 15 5 16 1 16 1 Q504 TAPE MODE E...

Page 23: ...2 20 2 21 BLOCK DIAGRAM ...

Page 24: ...2 22 2 23 SCHEMATIC DIAGRAMS 1 MAIN SCHEMATIC DIAGRAM ...

Page 25: ...2 24 2 25 2 µ COM SCHEMATIC DIAGRAM ...

Page 26: ...2 26 2 27 2 µ COM SCHEMATIC DIAGRAM FOR MP3 ...

Page 27: ...3 TUNER SCHEMATIC DIAGRAM 2 28 2 29 ...

Page 28: ...2 30 2 31 4 CD SCHEMATIC DIAGRAM ...

Page 29: ...4 CD SCHEMATIC DIAGRAM FOR MP3 2 32 2 33 ...

Page 30: ...2 34 2 35 5 DECODER SCHEMATIC DIAGRAM FOR MP3 ...

Page 31: ... WIRING DIAGRAM 2 36 2 37 ...

Page 32: ...2 38 2 39 PRINTED CIRCUIT BOARD DIAGRAMS 1 MAIN P C BOARD DIAGRAM COMPONENT SIDE ...

Page 33: ...2 40 2 41 1 MAIN P C BOARD DIAGRAM SOLDER SIDE ...

Page 34: ...2 µ COM P C BOARD DIAGRAM COMPONENT SIDE 2 µ COM P C BOARD DIAGRAM SOLDER SIDE SIDE 2 µ COM P C BOARD DIAGRAM COMPONENT SIDE FOR MP3 2 µ COM P C BOARD DIAGRAM SOLDER SIDE SIDE FOR MP3 2 42 2 43 ...

Page 35: ...3 CD P C BOARD DIAGRAM COMPONENT SIDE 2 44 2 45 3 CD P C BOARD DIAGRAM SOLDER SIDE SIDE ...

Page 36: ... 452 298 297 286 290 451 289 286 280 A44 A26 A00 450 A46 291 454 A48 310 285 A42 292 288 287 283 284 281 283 282 450 455 450 299 451 260 261 257 453 259 453 NOTE Refer to SECTION 4 REPLACEMENT PARTS LIST in order to look for the part number of each part SECTION 3 EXPLODED VIEWS CAUTION Exposed blade will cause severe injury ...

Page 37: ...3 3 3 4 MEMO MEMO ...

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