LG LH-T255SD Service Manual Download Page 27 | Manualshive

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3-2

2. Test & debug flow

TEST

Check the POWER PART

No

Yes

No

Yes

No

No

Yes

Yes

Check the POWER PART

Check the regulators or diode(D501).

1. Check 27MHz system clock.
2. Check systemreset circuit.
3. Check FLASH R/Wenable signal PRD,
RWR.
4. Check FLASH Memory related circuit.

Check the

AC Vol tage

Power PCBA (110V

or 220V)

Switch on the Power PCBA

Is the

DC Voltage outputs

OK?(-34V,-9V,36V,5.6V,

5V,8V,9V,2.5V,

3.3V)

Are 3.3V and 5V DC

outputs normal on main

PCBA?

Update

FLASH(IC500)

successfully?

Replace FLASH( IC500)

A

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Summary of Contents for LH-T255SD

Page 1: ...DVD CD RECEIVER SERVICE MANUAL MODEL LH T255SD LHS 25SDS LHS 25SDW MODEL LH T255SD LHS 25SDS LHS 25SDW SERVICE MANUAL ...

Page 2: ...PART AUDIO TROUBLESHOOTING GUIDE 2 1 BLOCK DIAGRAM 2 4 SCHEMATIC DIAGRAMS 2 6 WIRING DIAGRAM 2 20 PRINTED CIRCUIT DIARGAMS 2 22 SECTION 3 DVD AMP PART ELECTRICAL TROUBLESHOOTING GUIDE 3 1 DVD PART SCHEMATIC DIAGRAMS 3 22 SECTION 4 EXPLODED VIEWS 4 1 SECTION 5 SPEAKER PART 5 1 SECTION 6 REPLACEMENT PARTS LIST 6 1 ...

Page 3: ...ser beams 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 the...

Page 4: ... replacing 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 ...

Page 5: ...arges 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...

Page 6: ... Tuning Range 87 5 108 0 MHz or 65 0 74 0 MHz 87 5 108 0 MHz Intermediate Frequency 10 7 MHz Signal to Noise Ratio 60 dB Mono Frequency Response 140 10 000 Hz AM MW Tuning Range 522 1 620 kHz or 520 1 720 kHz Intermediate Frequency 450 kHz AMPLIFIER Stereo mode 30W 30W 6Ω at 1 kHz THD 10 Surround mode Front 30W 30W THD 10 Center 30W Surround 30W 30W 6Ω at 1 kHz THD 10 Subwoofer 70W 8Ω at 30 Hz THD...

Page 7: ......

Page 8: ...2 1 SECTION 2 AUDIO PART AUDIO TROUBLESHOOTING GUIDE 1 POWER SUPPLY CIRCUIT ...

Page 9: ...2 2 2 FRONT CIRCUIT 1 2 PIN3 PIN4 PIN9 27 5 FL 32 4 VKK 23 7 FL 5 0 CN902 CN902 ...

Page 10: ...2 3 3 FRONT CIRCUIT 2 2 ...

Page 11: ......

Page 12: ...2 4 2 5 BLOCK DIAGRAM NOTES Warning NOTES Parts that are shaded are critical NOTES With respect to risk of fire or NOTES electricial shock ...

Page 13: ...2 7 SCHEMATIC DIAGRAMS 1 POWER SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T NOTES Warning NOTES Parts that are shaded are critical NOTES With respect to risk of fire or NOTES electricial shock ...

Page 14: ...2 8 2 9 2 POWER SUB SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 15: ...2 10 2 11 3 MICOM SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 16: ...2 12 2 13 4 FRONT SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 17: ...2 14 2 15 5 DSP AMP SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 18: ...2 16 2 17 6 I O SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 19: ...2 18 2 19 7 MAIN MIC SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T ...

Page 20: ...2 20 2 21 NOTES Warning NOTES Parts that are shaded are critical NOTES With respect to risk of fire or NOTES electricial shock WIRING DIAGRAM ...

Page 21: ...2 22 2 23 PRINTED CIRCUIT BOARD DIAGRAMS 1 MAIN DVD P C BOARD DIAGRAM TOP ...

Page 22: ...2 24 2 25 2 MAIN DVD P C BOARD DIAGRAM BOTTOM ...

Page 23: ...2 26 2 27 3 FRONT P C BOARD ...

Page 24: ...2 28 2 29 4 SMPS P C BOARD LOCATION GUIDE NOTES Warning NOTES Parts that are shaded are critical NOTES With respect to risk of fire or NOTES electricial shock 5 JACK P C BOARD ...

Page 25: ......

Page 26: ...ion Recieve OPEN CLOSE Key Receive CLOSE Key 1 Stop Playback Open Tray 2 Display tray open message LOGO 1 Execute Pressed Key IR Key 2 Systemoperati on Routi ne Loop 1 Judge whether have disc and disc type 2 Jump to related disc reading procedure SLED at Inner Side 1 8082 initializes SERVO DSP RISC registers 2 Write RISC code to SDRAM 3 Reset RISC SECTION 3 DVD AMP PART ...

Page 27: ...stem clock 2 Check systemreset circuit 3 Check FLASH R Wenable signal PRD RWR 4 Check FLASH Memory related circuit Check the AC Vol tage Power PCBA 110V or 220V Switch on the Power PCBA Is the DC Voltage outputs OK 34V 9V 36V 5 6V 5V 8V 9V 2 5V 3 3V Are 3 3V and 5V DC outputs normal on main PCBA Update FLASH IC500 successfully Replace FLASH IC500 A ...

Page 28: ...3 3 A 115 ...

Page 29: ...3 4 B 1 2 ...

Page 30: ...3 5 C ES6698 ES6698 ES6698 ...

Page 31: ...3 6 D ...

Page 32: ...k connection between IC300 ABCK ALRCK ASDAT Check the related circuit of PWM Check Audio out Pins52 54 55 59 62 68 Normal PWM IC out IC300 PWM IC received correct data stream Check Digital Amp circuit IC301 IC302 ...

Page 33: ... it appear DVD Error at FLD Refer to SMPS Refer to oscillator Circuit Check IC101 Reset Waveform Check 3 3V line Check Power section Circuit NO Check power part of Main B D Check oscillator of X101 Check if IC101 Pin80 is high Check if IC101 Pin32 51 80 are high 5V Check if IC101 Pin96 is high Replace IC101 NO NO Check if DVD an Audio Micom Insert is OK Check Power YES Check DVD Module YES Check S...

Page 34: ... DEBUGGING 1 SYSTEM 27MHz CLOCK RESET FLASH R W SIGNAL 1 ES6698FD main clock is at 27MHz X501 3 8V 27MHz FIG 1 1 2 ES6698FD reset is high active PWR_CTL SYSTEM µ COM IC501 PIN83 5 2VA Power Cord in M_RESET IC501 PIN 207 URST IC501 PIN 188 FIG 1 2 ...

Page 35: ... 10 2 SDRAM CLOCK 1 ES6698FD main clock is at 27MHz X501 IC503 PIN 38 DCLK 93MHz Vp p 2 2 Vmax 2 7V FIG 2 1 4 Flash R W enable signal during download Downloading FRD IC500 PIN 28 FWR IC500 PIN 11 FIG 1 4 ...

Page 36: ...LOSE SIGNAL 1 Tray open close waveform OPEN PDM03 PIN7 CLOSE PDM03 PIN8 TROPEN IC402 PIN 4 TRCLOSE IC402 PIN 5 FIG 3 1 2 Tray close waveform OPEN PDM03 PIN7 CLOSE PDM03 PIN8 TROPEN IC402 PIN 4 TRCLOSE IC402 PIN 5 FIG 3 2 ...

Page 37: ...DISC CONDITION FMSO 2 0V 1 4V 1 0V IC501 PIN 19 STBY 5V IC401 PIN 50 SL 4 7V 3 6V 1 9V IC404 PIN 12 SL 5 3V 3 7V 2 5V IC404 PIN 11 FIG 4 1 3 Tray open waveform OPEN PDM03 PIN7 CLOSE PDM03 PIN8 TROPEN IC402 PIN 4 TRCLOSE IC402 PIN 5 FIG 3 3 ...

Page 38: ...ION FOSO 1 5V 1 4V 1 3V IC501 PIN 12 F 4 0V 3 6V 3 2V IC404 PIN 14 F 4 0V 3 6V 3 2V IC404 PIN 13 FIG 5 1 6 LASER POWER CONTROL RELATED SIGNAL NO DISC CONDITION MDI1 0V 180mV IC401 PIN 26 LD01 5 0V 3 5V IC401 PIN 20 LD02 5 0V 3 6V IC401 PIN 21 FIG 6 1 ...

Page 39: ...3 14 F IC404 PIN 14 FE IC401 PIN 40 RFL IC401 PIN 19 FIG 7 2 DVD 7 DISC TYPE JUDGEMENT WAVEFORMS F IC404 PIN 14 FE IC401 PIN 40 RFL IC401 PIN 19 FIG 7 1 DVD ...

Page 40: ...3 15 F IC404 PIN 14 FE IC401 PIN 40 RFL IC401 PIN 19 FIG 7 3 CD F IC404 PIN 14 FE IC401 PIN 40 RFL IC401 PIN 19 FIG 7 4 CD ...

Page 41: ...3 16 FE IC401 PIN 40 FOSO IC501 PIN12 F IC404 PIN 14 F IC404 PIN 13 FIG 8 2 CD 8 FOCUS ON WAVEFORMS FE IC401 PIN 40 FOSO IC501 PIN12 F IC404 PIN 14 F IC404 PIN 13 FIG 8 1 DVD ...

Page 42: ... NO DISC CONDITION DMSO 1 4V 1 8V IC501 PIN 18 SP 3 6V 2 4V IC404 PIN 18 SP 3 6V 4 8V IC404 PIN 17 FIG 9 1 10 TRACKING CONTROL RELATED SIGNAL System checking TE IC401 PIN 39 TRSO IC501 PIN 13 T IC404 PIN 16 T IC404 PIN 15 FIG 10 1 DVD ...

Page 43: ...3 18 11 RF WAVEFORM RFOP 2 3V 1 1V IC401 PIN 55 RFON 0 8V 2 0V IC401 PIN 57 FIG 11 1 TE IC401 PIN 39 TRSO IC501 PIN 13 T IC404 PIN 16 T IC404 PIN 15 FIG 10 2 CD ...

Page 44: ...3 19 12 ES6698FD VIDEO OUTPUT WAVEFORMS 1 Full colorbar signal COMPOSIT IC501 PIN 110 FIG 12 1 2 Y IC501 PIN 113 FIG 12 2 ...

Page 45: ...3 20 1 Audio L R FIG 13 1 13 AUDIO OUTPUT FROM PWM IC IC300 PIN 68 49 2 Audio related Signal ASDAT0 IC501 PIN 117 ABCK IC501 PIN 123 ALRCK IC501 PIN 116 ASDATA3 FIG 13 2 ...

Page 46: ...3 21 1 R315 FRONT L 2 R310 FRONT R 3 R316 REAR 4 R324 REAR 5 R303 CENTER 6 R317 WOOFER 14 DVD AMP WAVEFORMS ...

Page 47: ......

Page 48: ...A B C D E F G H I J K L M N O P Q R S T 3 22 3 23 DVD PART SCHEMATIC DIAGRAMS 1 DVD MPEG DSP SCHEMATIC DIAGRAM ...

Page 49: ...A B C D E F G H I J K L M N O P Q R S T 3 24 3 25 2 RF SERVO SCHEMATIC DIAGRAM ...

Page 50: ...3 FRONT MIC SCHEMATIC DIAGRAM A B C D E F G H I J K L M N O P Q R S T 3 26 3 27 ...

Page 51: ......

Page 52: ...3 463 351 463 463 463 A26 283 452 A41 274 274 452 A50 261 261 261 OPTIONAL PART NOTES THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE 4 1 4 2 SECTION 4 EXPLODED VIEWS ...

Page 53: ...EMBLY DECK MECHA LOADING DP 9 SH 015A 4680R E008A MOTOR MECH FEEDING RF 300EA 1D390 MABUCHI NSP 015B 4560R 0008A PULLEY MOTOR 016 6871R 9294A PWB PCB ASSEMBLY TOTAL DP 9C LOADING 017 4470R 0176A GEAR DVD DP 9 LOADING MOLD 018 4974R 0067A GUIDE DVD DP 9C UP DOWN MOLD 019 3210R M008A FRAME DP 9C UP DOWN MOLD 020 3040R M066A BASE MAIN DP 9T MOLD NSP 021 4681R B009B MOTOR ASSEMBLY DECK MECHA DP9 FEEDI...

Page 54: ...5 1 SECTION 5 SPEAKER SECTION MODEL LHS 25SDS 852 853 851 850 854 A800 ...

Page 55: ...5 2 MODEL LHS 25SDW A900 953 954 955 956 958 957 950 ...

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