Panasonic Viera TX-20LA60F User manual

ORDER NO. PCZ0610103CE
Service Manual
LCD TV
© 2006 Matsushita Electric Industrial Co., Ltd.
All rights reserved. Unauthorized copying and
distribution is a violation of law.
Power Source
AC 220-240V, 50Hz.
Power Consumption
Average use: 41W
Standby condition: 1W
LCD
VGA (640 × 480 pixels)
4:3 aspect ratio LCD panel
Screen Size
408 mm(W) × 306 mm(H)
Sound
Speaker
9 cm × 5cm, 2pcs, 4Ω
Audio Output
4W (2W + 2W), 20% THD
Headphones
M3 (3.5 mm) Jack x 1
Receiving Systems/ Band name
VHF BAND I: CH2-CH4
BAND II: CH5-CH12
UHF HYPER BAND :SI’-S3’, S1-S20
BAND IV, V : CH21-CH68
PAL-B/G, D/K, SECAM-L/L’, NTSC(AV input only)
Aerial-Rear
UHF/VHF
TX-20LA60F
TX-20LA60P
TX-20LA6F
TX-20LA6P
SL-131PP Chassis
Operating Conditions
Temperature: -10°C ~ 40°C
Humidity: 0%-90% RH (non-condensing)
Connection Terminals
AV1 (Scart connecter)
21 Pin terminal (Audio/Video in, Audio/Video out, RGB in)
AV2
VIDEO
RCA PIN Type × 1
S-VIDEO
Mini DIN 4-pin
AUDIO L-R
RCA PIN Type × 2
Dimensions (W x H x D)
Including TV Stand
498mm(W) × 260mm(D) × 493mm(H)
TV Set Only
498mm(W) × 95mm(D) × 451mm(H)
Weight
10.9kg Net
Note:
Design and Specifications are subject to change without notice.
Weight and Dimensions shown are approximate.

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CONTENTS
Page
1. Safety Precautions ----------------------------------------------- 3
1.1. General Guidelines -------------------------------------- 3
1.2. Touch-Current Check ------------------------------------ 3
2. Prevention of Electro Static Discharge (ESD) to
Electrostatically Sensitive (ES) Devices ------------------ 4
3 About lead free solder (PbF) --------------------------------- 5
4. Self Check ---------------------------------------------------------- 6
5. Chasis Board Layout -------------------------------------------- 7
6. Before servicing -------------------------------------------------- 8
6.1. Wire dressing ---------------------------------------------- 8
7. Disassembly for service --------------------------------------- 9
7.1. Stand ass´y ------------------------------------------------ 9
7.2. Back cover ------------------------------------------------- 9
7.3. CTRL ass´y -----------------------------------------------10
7.4. Power Swith ass´y --------------------------------------10
7.5. LED ass´y -------------------------------------------------10
7.6. Headphone ass’y ----------------------------------------10
7.7. Speaker (left and right) ---------------------------------11
7.8. TTL ass’y ---------------------------------------------------11
7.9. Power Module --------------------------------------------11
7.10. Main ass´y -----------------------------------------------11
7.11.Panel LCD-------------------------------------------------12
Page
8.Service Mode Function ----------------------------------------13
8.1. How to enter SERVICE --------------------------------13
8.2. How to exit SERVICE ----------------------------------13
8.3. Option Description --------------------------------------14
9. Conduct Views ---------------------------------------------------15
9.1. Foil Side ---------------------------------------------------15
9.2. Component Side -----------------------------------------17
10. Block and Schematic Diagrams --------------------------19
10.1. Schematic Diagram Notes ---------------------------19
10.2. Block Diagram ------------------------------------------20
10.3. Schematic Diagram -----------------------------------21
11. Parts Location & Replacement Parts List -------------28
11.1. Different Part List ---------------------------------------28
11.2. Exploded View ------------------------------------------29
11.3. Stand Assy Exploded View --------------------------30
11.4. Packing Exploded Views -----------------------------30
11.5. Electrical Replacement Parts List ------------------31

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1.Safety Precautions
1.1. General Guidelines
1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
3. After servicing, make the following leakage current checks to prevent the customer from being exposed to shock hazards.
1.2. Touch-Current Check
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.
2. Connect a measuring network for touch currents between each exposed metallic part on the set and a good earth ground such
as a water pipe, as shown in Figure 1.
3. Use Leakage Current Tester (Simpson 228 or equivalent) to measure the potential across the measuring network.
4. Check each exposed metallic part, and measure the voltage at each point.
5. Reserve the AC plug in the AC outlet and repeat each of the above measure.
6. The potential at any point (TOUGH CURRENT) expressed as voltage U1 and U2, does not exceed the following values:
For a. c.: U1= 35 V (peak) and U2= 0.35 V (peak);
For d. c.: U1= 1.0 V,
Note:
The limit value of U2 = 0.35 V (peak) for a. c. and U1 = 1.0 V for d. c. correspond to the values 0.7 mA (peak) a. c. and 2.0
mA d. c.
The limit value U1 = 35 V (peak) for a. c. correspond to the value 70 mA (peak) a. c. for frequencies greater than 100 kHz.
7. In case a measurement is out of the limits specified, there is a possibility of a shock hazard, and the equipment should be
repaired and rechecked before it is returned to the customer.

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2.Prevention of Electro Static Discharge (ESD) to
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 electro static discharge (ESD).
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any ESD on your
body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging ESD wrist strap,
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 almi-
num foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as „anti-static (ESD protected)” can
generate electrical charge sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most
replacement ES devices are packaged with leads electrically shorted together by conductive foam, alminum 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. (Otherwise hamless motion such as the brush-
ing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity (ESD) sufficient
to damage an ES device).

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3.About lead free solder (PbF)
Note: Lead is listed as (Pb) in the periodic table of elements.
In the information below, Pb will refer to Lead solder, and PbF will refer to Lead Free Solder.
The Lead Free Solder used in our manufacturing process and discussed below is (Sn+Ag+Cu).
That is Tin (Sn), Silver (Ag) and Copper (Cu) although other types are available.
This model uses Pb Free solder in it’s manufacture due to environmental conservation issues. For service and repair work, we’d
suggest the use of Pb free solder as well, although Pb solder may be used.
PCBs manufactured using lead free solder will have the PbF within a leaf Symbol stamped on the back of PCB.
Caution
• Pb free solder has a higher melting point than standard solder. Typically the melting point is 50 ~ 70 °F (30~40°C) higher.
Please use a high temperature soldering iron and set it to 700 ± 20 °F (370 ± 10 °C).
• Pb free solder will tend to splash when heated too high (about 1100 °F or 600 °C).
If you must use Pb solder, please completely remove all of the Pb free solder on the pins or solder area before applying Pb
solder. If this is not practical, be sure to heat the Pb free solder until it melts, before applying Pb solder.
• After applying PbF solder to double layered boards, please check the component side for excess solder which may flow onto
the opposite side. (see figure below)
Suggested Pb free solder
There are several kinds of Pb free solder available for purchase. This product uses Sn+Ag+Cu (tin, silver, copper) solder.
However, Sn+Cu (tin, copper), Sn+Zn+Bi (tin, zinc, bismuth) solder can also be used.

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4.Self Check
1. Self-Check is used to automatically check the bus lines and hexadecimal code of the TV set.
2. To get into the Self -Check mode press the Down ( ) button on the TV set, at the same time pressing the Recall ( )
button on the remote control, and the screen will show when the self Check is finished:
Programm number
Software Type
When Self Check is
finished you have this line
within the option definition.
SEDNA VERSION
3. Turn off the TV to reset after SELF-CHECK menu.

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5. Chassis Board Layout
Board Name Function
MAIN ASSY Main Board
CTRL ASSY Select Switch
HEADPHONE ASSY Headphone socket
LED ASSY Remote Receiver, LED
POWER SWITCH ASSY Main power switch
TTL ASSY Adapter of FFC cable
POWER MODULE Power Module
POWER
MODULE MAIN ASSY
LED ASSY CTRL ASSY
HEADPHONE ASSY POWER SWITCH
ASSY
TTL ASSY

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6. Before servicing
6.1. Wire dressing
Check a wire dressing is same as illustrated below;
CN2
P803
P602
Fix by tape
6.1.1 Connection
1. Connect every connector surely as ilustrated above photo ( A~ K).
2. Manage wires not to touch any sharp edge of the metal parts.
3. Manage wires not to have too much tension.
6.1.2 Clamping
Wire
Clamp wire
4956800200
Clamp wire
4856815900 Loop wire
AP501 - P501A
connection wire 4850705S30 7
BP502 - P502 on Power Module
connection wire 4850705N39
CP902 - P905 on TTL Ass’y
cable FFC 4859006560
DP504 - P504A
connection wire 4850704S84 32
EP601 - (L)SPEAKER
connection wire 4850703S77 71
FP602 - (R)SPEAKER
connection wire 4850703S77 5,6
GP803 - P801 on Power Module
connection wire 4850710S32 3,4 2
HPA09 - PA09B
connection wire 4850705S28 1
ICN2 - P500 on Power Module
connection wire 4850703N47 4,5,6
JP401 and P404 on Power Module
LCD panel connection wire
K„P405 and P408 on Power Module
LCD panel connection wire
E
F
G
A
B
C
D
H
I
J
1
P504
P601
PA09
P501
K
2
3
4
56
7
P502 P902
P905
P408 P405
P502
P801
P404 P401
P500
Fix by tape

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7. Disassembly for service
7.1 Stand Ass’y
1. Lay down the main unit so that the back cover faces
upward.
2. Remove the fixing screws (4pcs )
3. Remove the stand ass’y
7.2. Back cover
1. Remove stand ass’y (see 7.1.)
2. Remove the fixing screws (9pcs )
3. Take out the Terminal Cover ( )
4. Release the Cord Holder ( )
5. Pull Power Cord plug throgh Back Cover hole.
6. Remove Back Cover.

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7.3. CTRL Ass’y
1. Remove the back cover (see. 7.2.).
2. Disconnect wires: CN2 and P504.
3. Remove CTRL Panel Ass’y.
4. Remove screws (2 pcs ).
5. Remove CTRL PCB.
7.4. Power Switch Ass’y
1. Remove the back cover (see. 7.2.).
2. Disconnect wires: CN2 and P504.
3. Remove CTRL Panel Ass’y.
4. Remove screws (3 pcs ).
5. Remove Button CTRL Ass’y.
6. Remove Button Power and fixing screws (2 pcs ).
7. Remove Power Switch Ass’y.
7.5. LED Ass’y
1. Remove the back cover (see. 7.2.).
2. Disconnect wire: P501
3. Remove screw (1 pcs )
4. Remove LED PCB.
7.6. Headphone Ass’y
1. Remove the back cover (see. 7.2.).
2. Disconnect wire: PA09
3. Remove screw (1 pcs )
4. Remove Headphone PCB
P501
PA09

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7.7. Speaker (left and right)
1. Remove the back cover (see. 7.2.)
2. Disconnect wires: P601 and P602
3. Remove screws (8 pcs )
4. Remove Speakers.
7.8. TTL Ass’y
1. Remove the back cover (see. 7.2.)
2. Unlock P902 connector clip.
3. Disconnect FFC cable.
4. Remove TTL PCB from LCD panel.
5. Unlock P905 connector clip.
6. Remove FFC cable.
7.9. Power Module
1. Remove the back cover (see. 7.2.).
2. Disconnect wires: P500, P502, P801
3. Disconnect LCD panel wires: P401, P404, P405, P408
4. Remove screws (4 pcs ).
5. Remove Power Module.
7.10. Main Ass’y
1. Remove the back cover (see. 7.2.)
2. Disconnect wires: P501, P502, P504, P601, P602,
P803, P902, PA09
3. Remove screws (4 pcs ).
4. Remove Main PCB Ass’y.
P602
P404
PA09
P601
P401
P502 P801 P500
P502 P902
P601P504P803
P902
P408
P405
P602P501
P905

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7.11. Panel LCD
1. Remove the back cover (see. 7.2.)
2. Take out CTRL Panel Ass’y.
3. Take out TTL Ass’y.
4. Disconnect cables and unlock from clap wire: P401,
P404, P405, P408, P501, P601, P602, PA09
5. Remove screws (12 pcs ).
6. Take Main Frame Ass’y out of Front Mask.
7. Unscrew LCD Panel and Main Frame (4 screws
8. Remove LCD Panel.

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8. Service Mode Function
MPU controls the functions switching for each IICs through IIC bus in this chassis. The following setting and adjustment can be
adjusted by remote control in Service Mode.
8.1. How to enter SERVICE
Simultaneously press MUTE button ( ) on remote control and program DOWN button ( ) on the TV set.
RED GAIN 46
GRN GAIN 43 BLUE GAIN 45 RED BIAS 32
GRN BIAS 32
AGC LEVEL 24
CCU OFF
SHIPPING
4C 3C
OPTION1 3C
OPTION 2 4F AVL 00
ADC GAIN
GREEN 18
ADC GAIN
BLUE 18
ADC CLAMP
RED 10
ADC CLAMP
GREEN 10
ADC CLAMP
BLUE 10
ADC GAIN
RED 18
26 16 09 06
99
Key Command
* Press the selection button ( ) or program up/down button ( ) to step up/down through the functions.
* Press the selection button ( ) or volume up/down button( ) to change the function values.
* Each adjustment values will stored automatically.
8.2. How to exit SERVICE
To exit from Service mode, press menu or Power button on remote control.

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8.3. Option Description
There are two option bytes available (16 bits in all). These option bits are available from FACTORY and SERVICE mode. First
find the OPTION1 or OPTION2 control, and then use the UP/DOWN and PLUS/MINUS keys on the relevant remote keypad to
control the bits. The table below shows the two option bytes available;
8.3.1 OPTION 1
B7 B6 B5 B4 B3 B2 B1 B0
1
TOP
Teletext
OFF
FASTEXT
(FLOF) OFF PANEL 4:3 Not used
Dolby
Virtual
OFF
PC
Disable
TUNER OPTIONS
00 = Philips
01 = Not used
10 = Alps
11 = Partsnic
0
TOP
Teletext
ON
FASTEXT
(FLOF) ON PANEL 15:9 Not used
Dolby
Virtual
ON
PC
Enable
8.3.2 OPTION 2
B7 B6 B5 B4 B3 B2 B1 B0
1
Fixed to ‘0’
PANASONIC
remote
control
Must be set
to ‘0’ Not used Not used Full ATSS Must be set to ‘0’
Must be set
to ‘0’
0
Daewoo
Remote
control
Must be set
to ‘0’ Not used Not used Basic ATSS Must be set to ‘0’
Must be set
to ‘0’

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9. Conduct Views
9.1. Foil Side

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9.2. Component Side
IC TRANSISTOR CRYSTAL QUARTZ
I402
I501
I502
I503
I504
I508
I601
I603
I801
I803
I807
I809
I811
I816
I820
I851
IC13
F3
D3,E3
C4
E4,F4
C2
D4,D5
G5,H5
G5,H5
G3
G4
B4
G4
E2
C5
H3
G4,H4
E5
Q120
Q506
Q508
Q602
Q701
Q702
Q802
Q803
Q804
Q805
Q813
Q814
Q815
Q816
Q820
Q850
QA04
QA08
QA12
QA13
QA21
QA71
QA72
QA74
QA75
C2
B1
C3
H4
A5
B5
G3
G3
G3
H4
B5
B5
B5
B5
H3
H3
G2
G2
B2
B2
G2
C2
C2
C2
B2
X201
X501
F3
C3
FILTER SAW
Z101
Z102
C3
C3
Part Location

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10. Block and Schematic Diagrams
10.1.Schematic Diagram Notes

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10.2. Block Diagram