LG LST-3100A User manual

SET-TOP BOX
SERVICE MANUAL
MODEL : LST-3100A
MODEL : LST-3100A
SERVICE MANUAL
P/NO : 3829RVN006Q
AUGUST, 2003
Printed in Korea
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.

CONTENTS
SECTION 1 . . . .SUMMARY
SECTION 2 . . . .CABINET & MAIN CHASSIS
SECTION 3 . . . .ELECTRICAL
SECTION 4 . . . .REPLACEMENT PARTS LIST

SECTION 1
SUMMARY
CONTENTS
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS ......... 1-3
SERVICING PRECAUTIONS .................................................................................. 1-4
• General Servicing Precautions
• Insulation Checking Prodedure
• Electrostatically Sensitive Devices
SPECIFICATIONS ................................................................................................... 1-5

1-3
CAUTION : DO NOT ATTEMPT TO MODIFY THIS PRODUCT IN ANY WAY,
NEVER PERFORM CUSTOMIZED INSTALLATIONS WITHOUT MANUFAC-
TURER’S APPROVAL. UNAUTHORIZED MODIFICATIONS WILL NOT ONLY
VOID THE WARRANTY, BUT MAY LEAD TO YOUR BEING LIABLE FOR ANY
RESULTING PROPERTY DAMAGE OR USER INJURY.
SERVICE WORK SHOULD BE PERFORMED ONLY AFTER YOU ARE
THOROUGHLY FAMILIAR WITH ALL OF THE FOLLOWING SAFETY
CHECKS AND SERVICING GUIDELINES. TO DO OTHERWISE,
INCREASES THE RISK OF POTENTIAL HAZARDS AND INJURY TO THE
USER.
WHILE SERVICING, USE AN ISOLATION TRANSFORMER FOR PROTEC-
TION FROM A.C. LINE SHOCK.
SAFETY CHECKS
AFTER THE ORIGINAL SERVICE PROBLEM HAS BEEN CORRCTED. A
CHECK SHOULD BE MADE OF THE FOLLOWING.
SUBJECT : FIRE & SHOCK HAZARD
1. BE SURE THAT ALL COMPONENTS ARE POSITIONED IN SUCH A WAY
AS TO AVOID POSSIBILITY OF ADJACENT COMPONENT SHORTS.
THIS IS ESPECIALLY IMPORTANT ON THOSE MODULES WHICH ARE
TRANSPORTED TO AND FROM THE REPAIR SHOP.
2. NEVER RELEASE A REPAIR UNLESS ALL PROTECTIVE DEVICES
SUCH AS INSULATORS, BARRIERS, COVERS, SHIELDS, STRAIN
RELIEFS, POWER SUPPLY CORDS, AND OTHER HARDWARE HAVE
BEEN REINSTALLED PER ORIGINAL DESIGN. BE SURE THAT THE
SAFETY PURPOSE OF THE POLARIZED LINE PLUG HAS NOT BEEN
DEFEATED.
3. SOLDERING MUST BE INSPECTED TO DISCOVER POSSIBLE COLD
SOLDER JOINTS, SOLDER SPLASHES OR SHARP SOLDER POINTS.
BE CERTAIN TO REMOVE ALL LOOSE FOREIGN PARTICLES.
4. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE OR DETERIORATION
TO PARTS AND COMPONENTS. FOR FRAYED LEADS, DAMAGED
INSULATION (INCLUDING A.C. CORD). AND REPLACE IF NECESSARY
FOLLOW ORIGINAL LAYOUT, LEAD LENGTH AND DRESS.
5. NO LEAD OR COMPONENT SHOULD TOUCH A RECIVING TUBE OR
A RESISTOR RATED AT 1 WATT OR MORE. LEAD TENSION AROUND
PROTRUNING METAL SURFACES MUST BE AVOIDED.
6. ALL CRITICAL COMPONENTS SUCH AS FUSES, FLAMEPROOF
RESISTORS, CAPACITORS, ETC. MUST BE REPLACED WITH EXACT
FACTORY TYPES, DO NOT USE REPLACEMENT COMPONENTS
OTHER THAN THOSE SPECIFIED OR MAKE UNRECOMMENDED CIR-
CUIT MODIFICATIONS.
7. AFTER RE-ASSEMBLY OF THE SET ALWAYS PERFORM AN A.C.
LEAKAGE TEST ON ALL EXPOSED METALLIC PARTS OF THE CABI-
NET, (THE CHANNEL SELECTOR KNOB, ANTENNA TERMINALS. HAN-
DLE AND SCREWS) TO BE SURE THE SET IS SAFE TO OPERATE
WITHOUT DANGER OF ELECTRICAL SHOCK. DO NOT USE A LINE
ISOLATION TRANSFORMER DURING THIS TEST USE AN A.C. VOLT-
METER, HAVING 5000 OHMS PER VOLT OR MORE SENSITIVITY, IN
THE FOLLOWING MANNER; CONNECT A 1500 OHM 10 WATT RESIS-
TOR, PARALLELED BY A .15 MFD. 150.V A.C TYPE CAPACITOR
BETWEEN A KNOWN GOOD EARTH GROUND (WATER PIPE, CON-
DUIT, ETC.) AND THE EXPOSED METALLIC PARTS, ONE AT A TIME.
MEASURE THE A.C. VOLTAGE ACROSS THE COMBINATION OF 1500
OHM RESISTOR AND .15 MFD CAPACITOR. REVERSE THE A.C. PLUG
AND REPEAT A.C. VOLTAGE MEASUREMENTS FOR EACH EXPOSED
METALLIC PART. VOLTAGE MEASURED MUST NOT EXCEED 75
VOLTS R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP A.C ANY
VALUE EXCEEDING THIS LIMIT CONSTITUTES A POTENTIAL SHOCK
HAZARD AND MUST BE CORRECTED IMMEDIATELY.
SUBJECT: GRAPHIC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN
AN EQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE
SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED
“DANGEROUS VOLTAGE”THAT MAY BE OF SUFFICIENT MAG-
NITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIAN-
GLE IS INTENDED TO ALERT THE SERVICE PERSONNEL TO
THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN
SERVICE LITERATURE.
SUBJECT : X-RADIATION
1. BE SURE PROCEDURES AND INSTRUCTIONS TO ALL SERVICE PER-
SONNEL COVER THE SUBJECT OF X-RADIATION. THE ONLY POTEN-
TIAL SOURCE OF X-RAYS IN CURRENT T.V. RECEIVERS IS THE PIC-
TURE TUBE. HOWEVER, THIS TUBE DOES NOT EMIT X-RAYS WHEN
THE HIGH VOLTAGE IS AT THE FACTORY SPECIFIED LEVEL. THE
PROPER VALUE IS GIVEN IN THE APPLICABLE SCHEMATIC. OPERA-
TION AT HIGHER VOLTAGES MAY CAUSE A FAILURE OF THE PIC-
TURE TUBE OR HIGH VOLTAGE SUPPLY AND, UNDER CERTAIN CIR-
CUMSTANCES, MAY PRODUCE RADIATION IN EXCESS OF DESIR-
ABLE LEVELS.
2. ONLY FACTORY SPECIFIED C.R.T. ANODE CONNECTORS MUST BE
USED. DEGAUSSING SHIELDS ALSO SERVE AS X-RAY SHIELD IN
COLOR SETS, ALWAYS RE-INSTALL THEM.
3. IT IS ESSNTIAL THAT SERVICE PERSONNEL HAVE AVAILABLE AN
ACCURATE AND RELIABLE HIGH VOLTAGE METER. THE CALIBRA
TION OF THE METER SHOULD BE CHECKED PERIODICALLY
AGAINST A REFERENCE STANDARD, SUCH AS THE ONE AVAILABLE
AT YOUR DISTRIBUTOR.
4. WHEN THE HIGH VOLTAGE CIRCUITRY IS OPERATING PROPERLY
THERE IS NO POSSIBILITY OF AN X-RADIATION PROBLEM. EVERY
TIME A COLOR CHASSIS IS SERVICED. THE BRIGHTNESS SHOULD
BE RUN UP AND DOWN WHILE MONITORING THE HIGH VOLTAGE
WITH A METER TO BE CERTAIN THAT THE HIGH VOLTAGE DOES
NOT EXCEED THE SPECIFIED VALUE AND THAT IT IS REGULATING
CORRECTLY, WE SUGGEST THAT YOU AND YOUR SERVICE ORGA-
NIZATION REVIEW TEST PROCEDURES SO THAT VOLTAGE REGU-
LATION IS ALWAYS CHECKED AS A STANDARD SERVICING PROCE-
DURE. AND THAT THE HIGH VOLTAGE READING BE RECORDER ON
EACH CUSTOMER’S INVOICE.
5. WHEN TROUBLESHOOTING AND MAKING TEST MEASUREMENTS IN
A PRODUCT WITH A PROBLEM OF EXCESSIVE HIGH VOLTAGE,
AVOID BEING UNNECESSARILY CLOSE TO THE PICTURE TUBE AND
THE HIGH VOLTAGE SUPPLY. DO NOT OPERATE THE PRODUCT
LONGER THAN IS NECESSARY TO LOCATE THE CAUSE OF EXCES
SIVE VOLTAGE.
6. REFER TO HV. B+ AND SHUTDOWN ADJUSTMENT PROCEDURES
DESCRIBED IN THE APPROPRIATE SCHEMATIC AND DIAGRAMS
(WHERE USED).
SUBJECT: IMPLOSION
1. ALL DIRECT VIEWED PICTURE TUBES ARE EQUIPPED WITH AN INTE
GRAL IMPLOSION PROTECTION SYSTEM, BUT CARE SHOULD BE
TAKEN TO AVOID DAMAGE DURING INSTALLATION, AVOID
SCRATCHING THE TUBE. IF SCRATCHED REPLACE IT.
2. USE ONLY RECOMMENDED FACTORY REPLACEMENT TUBES.
SUBJECT : TIPS ON PROPER INSTALLATION
1. NEVER INSTALL ANY PRODUCT IN A CLOSED-IN RECESS, CUBBY-
HOLE OR CLOSELY FITTING SHELF SPACE. OVER OR CLOSE TO
HEAT DUCT, OR IN THE PATH OF HEATED AIR FLOW.
2. AVOID CONDITIONS OF HIGH HUMIDITY SUCH AS: OUTDOOR PATIO
INSTALLATIONS WHERE DEW IS A FACTOR, NEAR STEAM RADIA-
TORS WHERE STEAM LEAKAGE IS A FACTOR, ETC.
3. AVOID PALCEMENT WHERE DRAPERIES MAY OBSTRUCT REAR
VENTING. THE CUSTOMER SHOULD ALSO AVOID THE USE OF DEC-
ORATIVE SCARVES OR OTHER COVERINGS WHICH MIGHT
OBSTRUCT VENTILATION.
4. WALL AND SHELF MOUNTED INSTALLATIONS USING A COMMER-
CIAL MOUNTING KIT. MUST FOLLOW THE FACTORY APPROVED
MOUNTING INSTRUCTIONS A PRODUCT MOUNTED TO A SHELF OR
PLATFORM MUST RETAIN ITS ORIGINAL FEET (OR THE EQUIVALENT
THICKNESS IN SPACERS) TO PROVIDE ADEQUATE AIR FLOW
ACROSS THE BOTTOM, BOLTS OR SCREWS USED FOR FASTENERS
MUST NOT TOUCH ANY PARTS OR WIRING. PERFORM LEAKAGE
TEST ON CUSTOMIZED INSTALLATIONS.
5. CAUTION CUSTOMERS AGAINST THE MOUNTING OF A PRODUCT ON
SLOPING SHELF OR A TILTED POSITION, UNLESS THE PRODUCT IS
PROPERLY SECURED.
6. A PRODUCT ON A ROLL-ABOUT CART SHOULD BE STABLE ON ITS
MOUNTING TO THE CART. CAUTION THE CUSTOMER ON THE HAZ-
ARDS OF TRYING TO ROLL A CART WITH SMALL CASTERS ACROSS
THRESHOLDS OR DEEP PILE CARPETS.
7. CAUTION CUSTOMERS AGAINST THE USE OF A CART OR STAND
WHICH HAS NOT BEEN LISTED BY UNDERWRITERS LABORATORIES,
INC. FOR USE WITH THEIR SPECIFIC MODEL OF TELEVISION
RECEIVER OR GENERICALLY APPROVED FOR USE WITH T.V.’S OF
THE SAME OR LARGER SCREEN SIZE.
8. CAUTION CUSTOMERS AGAINST THE USE OF EXTENSION CORDS,
EXPLAIN THAT A FOREST OF EXTENSIONS SPROUTING FROM A SIN-
GLE OUTLET CAN LEAD TO DISASTROUS CONSEQUENCES TO
HOME AND FAMILY.
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS
A.C. VOLTMETER
GOOD EARTH GROUND
SUCH AS THE WATER
PIPE. CONDUIT. ETC
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART

1-4
SERVICING PRECAUTIONS
CAUTION : Before servicing the STB covered by this service
data and its supplements and addends, read and follow the
SAFETY PRECAUTIONS. NOTE : if unforeseen circum-
stances create conflict between the following servicing pre-
cautions and any of the safety precautions in this publica-
tions, always follow the safety precautions.
Remembers Safety First:
General Servicing Precautions
1. Always unplug the STB AC power cord from the AC
power source before:
(1) Removing or reinstalling any component, circuit board,
module, or any other assembly.
(2) Disconnection or reconnecting any internal electrical
plug or other electrical connection.
(3) Connecting a test substitute in parallel with an elec-
trolytic capacitor.
Caution : A wrong part substitution or incorrect
polarity installation of electrolytic capacitors may result
in an explosion hazard.
2. Do not spray chemicals on or near this STB or any of
its assemblies.
3. Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact
cleaning solution to the contacts with a pipe cleaner,
cotton-tipped swab, or comparable soft applicator.
Unless specified otherwise in this service data, lubrication
of contacts is not required.
4. Do not defeat any plug/socket B+ voltage interlocks with
whitch instruments covered by this service manual might
be equipped.
5. Do not apply AC power to this STB and/or any of its
electrical assemblies unless all solid-state device heat
sinks are cerrectly installed.
6. Always connect test instrument ground lead to the
appropriate ground before connection the test instrument
positive lead. Always remove the test instrument ground
lead last.
Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet and turn
the power on. Connect an insulation resistance meter(500V)
to the blades of the attachment plug. The insulation resis-
tance between each blade of the attachment plug and acces-
sible conductive parts (Note 1) should be more than 1M-
ohm.
Note 1 : Accessible Conductive Parts including Metal pan-
els, Input terminals, Earphone jacks, etc.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged
easily by static electricity. Such components commonly are
called Electrostatically Sensitive (ES) Devices. Examples of
typical ES devices are integrated circuits and some field
effect transistors and semiconductor chip components.
The following techniques should be used to help reduce the
incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor compo-
nent or semiconductor-equipped assembly, drain off any
electrostatic charge on your body by touching a known
earth ground. Alternatively, obtain and wear a commer-
cially available discharging wrist strap device, which
should be removed for potential shock reasons prior to
applying power to the unit under test.
2. After removing an electrical assembly equipped with ES
devices, place the assembly on a conductive surface such
as aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
3. Use only a grouned-tip soldering iron to solder or unsolder
ES devices.
4. Use only an anti-static solder removal device. Some
solder removal devices not classified a “anti-static”can
generate electrical charges sufficient to damage ES
devices.
5. Do not use freon-propelled chemicals. These can
generate electrical charge sufficient to damage ES
devices.
6. Do not remove a replacement ES device from its protec
tive package until immediately before you are ready to
install it. (Most replacement ES devices are packaged with
leads electrically shorted together by conductive foam,
aluminum foil, or comparable conductive material).
7. Immediately before removing the protective material from
the leads of a replacement ES device, touch the protective
material to the chassis or circuit assembly into which the
device will be installed.
Caution : Be sure no power is applied to the chassis or
circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged
replacement ES devices. (Normally harmless motion such
as the brushing together of your clothes fabric or the lifting
of your foot from a carpeted floor can generate static elec-
tricity sufficient to damage an ES device.)

1-5
SPECIFICATIONS
Television System NTSC, DTV standard (1080i, 720p, 480p, 480i)
Channel Coverage Terrestrial: 2-69, Cable: 1-135
Input/Output
ATSC ANT Input ANT IN (1) (ATSC-8VSB over Terrestrial or QAM over cable)
ANT Loop Out Out To TV (1)
DVI Output DVI-HDTV Out (1), DVI-D Single Link connector
1080i, 720p, 480p digital RGB
Component Video Output Component Out (1 Set), Typical RCA type Jack connectors
1080i, 720p, 480p, 480i YPbPr
RGB Output RGB Out (1), 15-pin connector
1080i, 720p, 480p RGB
S-Video Output S-Video Out (1), 4-pin Mini-DIN
480i Y/C
Video Output Video Out (1), Typical RCA type Jack connector
480i Composite
Digital Audio Output Coaxial, Optical (Dolby Digital output)
Analog Audio Output Audio Out (2) (Variable Output Level)
Authorized Service Port 9-pin Serial Port (1)
Dimension (W x H X D) 14.2 x 2.4 x 10.4 inches (360 x 60 x 265 mm)
Weight 7.7 lbs (3.5 kg)
Power Requirements AC 120V, 60Hz
Power Consumption 15W
Environment
Humidity 0 to 99 percent non condensing
Storage Temperature -20 to 60 degrees Celsius (-4 to 140 degrees Fahrenheit)
Operating Temperature 0 to 40 degrees Celsius (32 to 104 degrees Fahrenheit)
Accessories
RF cable . . . . . . . . . . . . . . . . . . . . .1
Video cable . . . . . . . . . . . . . . . . . . .1
Audio (L/R) cable . . . . . . . . . . . . . . .1
Component (YPbPr) cable . . . . . . . .1
Remote Control . . . . . . . . . . . . . . . .1
Batteries (size AA) . . . . . . . . . . . . . .2

2-1
SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS .....................................................................................................................2-2
1. Cabinet and Main Frame Section ...........................................................................................2-2
2. Packing Accessory Section....................................................................................................2-3

2-2
EXPLODED VIEWS
1. Cabinet and Main Frame Section
300
A47
463
463
463
463
250
A46
463
463
A43
A44
A49
280
452
452
260
320
466
457
465
466
469
470
457
A
5
4
3
2
1
BCD

2-3
2. Packing Accessory Section
808
804
803
801
900
802
803
813 S-VIDEO CABLE
806 RF CABLE
823 TELEPHONE LINE
820 PLUG ASS'Y(3WAY)
PACKING SHEET
PACKING
BATTERY
822 SMART CARD
REMOCON
BOX CARTONX
PACKING
OWNER'S MANUAL
OPTIONAL PARTS
811
812
PLUG ASS'Y 1WAY
PLUG ASS'Y 2WAY

3-1
SECTION 3
ELECTRICAL
CONTENTS
SOFTWARE CORRUPTION PROBLEM.....................................................................................................3-2
ELECTRICAL TROUBLESHOOTING GUIDE............................................................................................3-5
1. POWER(SMPS) CIRCUIT.........................................................................................................................3-5
2. AUDIO CIRCUIT .......................................................................................................................................3-7
1) NO ATSC AUDIO.....................................................................................................................................3-7
2) NO OPTICAL OUTPUT AUDIO ...............................................................................................................3-11
3) NO COAXIAL OUTPUT AUDIO ..............................................................................................................3-12
3. CPU (SYSTEM CONTROL) TROUBLESHOOTING ..............................................................................3-14
4. VIDEO TROUBLESHOOTING FLOW ....................................................................................................3-21
5. ATSC/ QAM FRONT- END TROUBLESHOOTING FLOW ....................................................................3-31
6. FRONT PANEL TROUBLESHOOTING FLOW......................................................................................3-32
OVERALL BLOCK DIAGRAM.........................................................................................................................3-34
1. OVERALL BLOCK DIAGRAM 1 ............................................................................................................3-34
2. OVERALL BLOCK DIAGRAM 2 ............................................................................................................3-36
3. OVERALL BLOCK DIAGRAM 3 ............................................................................................................3-38
BLOCK DIAGRAM & SIGNAL FLOW.............................................................................................................3-40
1. POWER(SMPS) BLOCK DIAGRAM ......................................................................................................3-40
2. SYSTEM CONTRL BLOCK DIAGRAM..................................................................................................3-42
3. AUDIO PROCESSING BLOCK DIAGRAM............................................................................................3-44
4. VIDEO PROCESSING BLOCK DIAGRAM ............................................................................................3-46
CIRCUIT DIAGRAM .........................................................................................................................................3-48
1. POWER(SMPS) CIRCUIT DIAGRAM ....................................................................................................3-48
2. CPU, AUDIO, POWER CIRCUIT DIAGRAM..........................................................................................3-50
3. HD2, TUNER, DVI CIRCUIT DIAGRAM.................................................................................................3-52
4. ATSCII-STB CIRCUIT DIAGRAM...........................................................................................................3-54
5. FRONT CIRCUIT DIAGRAM ..................................................................................................................3-56
PRINTED CIRCUIT DIAGRAMS......................................................................................................................3-58
1. DIGITAL MAIN P.C.BOARD(BOTTOM)..................................................................................................3-58
2. DIGITAL MAIN P.C.BOARD(TOP)..........................................................................................................3-60
3. FRONT P.C.BOARD ...............................................................................................................................3-62
4. POWER P.C.BOARD ..............................................................................................................................3-62

SOFTWARE CORRUPTION PROBLEM
3-2
1. Open window display for Serial Communication like above.
- You can use almost kinds of serial communication programs, but we send the terminal
(LG Term) which is now used on our side.
2. Create “Setup-> Serial Port”like the display. (However, the port depends upon the user
environment so that you need to create properly.)
3. Create “Setup-> Terminal”like the above display.

3-3
4. After completing all set-up process, press d key in the terminal and impress STB power.
At this time, you should pull up the plug and then pull into the socket again.
- You have another choice. When activating, please enter “klLST3100”, “ENTER”and
then “F10”keys in sequence. Once the command mode is up, you can download it
even in your “Reset”command.
5. When above display shows up, you can download applications. You can input keys at the
prompt.
6. Press Enter Key several times to input new command. Input serial download command
as “sto ser”like above example and then press Enter key.
7. This is the condition you can download application program from STB.

3-4
8. In the downloadable condition, select °∞File->Send File°±. You can watch one more dis-
play like above. You should find °∞ram.biz°∞file in this new display and open it to start
downloading.
9. You can see the downloading process from display and it takes about 2 minutes to com-
plete. After downloading, the message °∞Please write data into the Flash ROM°± would
show up. (You may experience errors of downloading. Then, follow from No. 6 again.
10. Above message shows that you succeed to write application program into the Flash.
Restart the power source, or input °∞b flash°± in this display to activate properly.
(If you have no response, please input command again.)

3-5
ELECTRICAL TROUBLESHOOTING GUIDE
1. Power(SMPS) CIRCUIT
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES YES
YES
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
(1) No 5.0VA
Check or Replace
the D106
Check the ‘PWR CTL
“H”’ signal from µ-com
NO
NO
(2) No 5.0V
NO
(3) No 3.3V
No 5.0VA
Is the F101 normal?
Is the R105
Normal?
Is the BD101
normal?
Is Vcc (13V - 16V) sup-
plied to IC101 Pin7?
Are the D106
normal?
Is there about 2.5V
at the IC103 Pin1?
Is the D105
normal?
Is the D109
normal?
Replace the F101.
(Use the same Fuse)
Replace the
BD101.
Replace the R105.
Is the D103
normal?
Check or Replace
the D106.
Replace the
D106.
Replace the IC103.
Replace the
D105.
Replace the
D109.
Replace the
D110.
No 3.3V
Is there about 3.8V
at the IC153 pin1?
Is there about 3.3V~
5V at the IC153 pin4?
YES
Check the IC153
and Replace
Check or Replace
the D105
NO
Check the ‘PWR CTL
“H”’ signal from µ-com
Is there about 5.4V
at the IC152 pin1?
Is there about 3.3V~5V
at the IC152 pin4?
YES
Check the IC152
and Replace
Is the D110
normal?
NO Replace the
D108.
Is the D108
Normal?
NO 5.0V
YES
YES
Power Line of Main
PCB is short
NO Replace the
D107.
Is the D107
Normal?

3-6
YES
YES
NO
(4) No 12VA
Is there about 13V
at the IC155 pin1?
Is there about 3.3V~5V
at the IC155 pin4?
Check the IC155
and Replace
Check or Replace
the D109
NO
Check the ‘PWR CTL
“H”’ signal from µ-com
YES
YES
YES
YES
NO
NO
NO
(6) No VFD
No VFD
Is The R123
Normal?
Is The D107
Normal?
Is The ZD102
Normal?
Check and
Replace the D108
Replace the R123
Replace the R107
Replace the ZD102
YES
YES
NO
(5) No 30VA
No 30VA
Is The ZD110
Normal?
Check and
Replace the D110
Replace the ZD101

3-7
2. AUDIO CIRCUIT
1) NO ATSC AUDIO
NO
NO
NO
NO
NO
YES
YES
YES
YES
(1) Check IC110 and Surroundings
5V is supplied to IC110(14)?
12.2880MHz clock is input to IC110
(5)? Fig. 01
IC110(13) is grounded?
48KHz clock is output from IC110
(4)? Fig. 02
Data Signal is input to IC110(2)?
Fig. 03
YES
Analog Audio Signal from IC110
(12,15)? Fig. 04
Check the Power Supply Part.
Check 12.2880MHz Clock output at
IC200(H5).
Check 48KHz Clock ouput at IC200
(G5)
Check soldering.
Check Data Signal at IC200(G3)

3-8
Fig. 01 12.2880MHz clock
Fig. 02 48KHz clock
Fig. 04 Analog Audio SignalFig. 03 Data Signal

3-9
Fig. 05 Analog Audio Signal
NO
NO
NO
YES
YES
(2) Check IC112 and Surroundings
(3) Check Q102, Q103, Q109, Q110 and Surroundings
(4) Check Output Jack and Surroundings
59V is supplied to IC112(8)?
Analog audio signal is output from
IC112(1, 7)? Fig. 05
Analog audio signal is output from
Q102, Q103, Q109, Q110(1)? Fig. 06
9V is supplied to Q102, Q103,
Q109,Q110(3)?
Check CN300(VARIABLE_ L, VARIABLE_ R, MONITOR_ L, MONITOR_ R)
And their surroundings
Check Power Supply Part
Check IC112 and surroundings
NO Check Power Supply Part
Check Q102, Q103, Q109, Q110 and
surroundings

3-10
Fig. 06 Analog Audio Signal

3-11
2) NO OPTICAL OUTPUT AUDIO
NO
YES
SPDIF pulse is output from IC200
(F3)? Fig. 07
Check CN103 and surrounding
Check IC200 and surroundings