Panasonic TX-20LA80F, TX-2-LA80FS Service manual
ORDER No. PCZ0804036CE
Service Manual
Colour LCD Television
TX-20LA80F
TX-20LA80FS
GLP21L Chassis
Specifications
Power Source: 220-240V AC, 50Hz
Power Consumption: 52W
Stand-by Power
Consumption: 1W
Aerial Impedance: 75Ω unbalanced, Coaxial Type
Receiving System: PAL-B/G/I, D/K,
SECAM B/G, D/K, L/L’
PAL-525/60 (AV only)
M.NTSC (AV only)
NTSC (AV only)
Receiving Channels:
VHF E2-E12 VHF H1-H2 (ITALY)
VHF A-H (ITALY) VHF R1-R2
VHF R3-R5 VHF R6-R12
UHF E21-E69 CATV (S01-S05)
CATV S1-S10 (M1-M10) CATV S11-S20 (U1-U10)
CATV S21-S41 (Hyperband)
Operating Conditions:
Temperature: 5°C ÷ 35°C
Humidity: 5% ÷ 90% RH (non-condensing)
Intermediate Frequency:
Video/Audio
Video 38,9MHz, 33,9MHz
Audio 33,4MHz (B/G), 33,16MHz (A2)
33,05MHz (NICAM B/G, D/K, L)
32,4MHz (D/K), 32,66MHz (CZ STEREO)
40,4MHz (L’), 39,75MHz (L’NICAM),
32,35MHz,32,9MHz (NICAM)
Colour 34,47MHz (PAL)
34,5MHz, 34,65MHz (SECAM)
38,3MHz, 38,15MHz (SECAM L’)
Terminals:
AV1 IN Video (21 pin) 1V p-p 75Ω
Audio (21 pin) 500mV rms 10kΩ
RGB (21 pin) 0,7V p-p 75Ω AV1
OUT Video (21 pin) 1V p-p 75Ω
Audio (21 pin) 500mV rms 1kΩ
AV2 IN S-Video IN Y: 1V p-p 75Ω
(4-pin) C:0,3V p-p 75Ω
Video (RCAx1) 1V p-p 75Ω
AUDIO OUT Audio (RCAx2) 500mV rms 1kΩ
LCD screen: L5EDD5L00011
640 x 480 VGA, 4:3
Visible Diagonal 508mm
Audio Output: 2x3W RMS
8Ω impedance
Headphones: 3,5mm, 8Ω Impedance
Accessories
supplied : Remote Control
2 x R6 (UM3) Batteries
Dimensions:
Including TV stand 484mm 498mm 233mm
TV set only 443mm 498mm 98mm
Net weight: 7,5kg
Specifications are subject to change without notice.
Weights and dimensions shown are approximate.
Audio (RCAx2) 500mV rms 10kΩ
Height: Width: Depth:
Contents
SAFETY PRECAUTIONS........................................... 3
GENERAL GUIDE LINES...................................... 3
TOUCH – CURRENT CHECK............................... 3
PREVENTION OF ELECTROSTATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE (ES)
DEVICES.................................................................... 4
ABOUT LEAD FREE SOLDER (PBF)......................... 5
SUGGESTED PB FREE SOLDER........................ 5
SERVICE HINTS ........................................................ 6
CHASSIS BOARD LAYOUT....................................... 7
SETTING INSPECTION.............................................. 7
SELF-CHECK ............................................................. 8
ADJUSTMENT METHOD............................................9
BLOCK DIAGRAMS.................................................. 10
PARTS LOCATION................................................... 13
REPLACEMENT PARTS LIST.................................. 14
SCHEMATIC DIAGRAMS......................................... 21
A-BOARD SCHEMATIC DIAGRAM .................... 22
P-BOARD SCHEMATIC DIAGRAM .................... 23
V-BOARD SCHEMATIC DIAGRAM .................... 24
CONDUCTOR VIEWS .............................................. 25
2
Safety Precautions
Ω
μ
Ω
General Guide Lines
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 touch current checks to prevent the customer from being exposed to shock hazards.
4. Always ensure panel TKP0E16001 is correctly replaced before returning to customer (see Fig.1).
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 Fig. 2.
3. Use Leakage Current Tester (Simpson 228 or equivalent) to measure the potential acr oss 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 (TOUCH 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 shoul d
be repaired and rechecked before it is returned to the customer.
COLD
WATER PIPE
(EARTH GROUND)
TO
APPLIANCES
EXPOSED
METAL PARTS
Resistance values in ohms (Ω)
V: Voltmetr or oscilloscope
(r.m.s. or peak reading)
NOTE – Appropriate measures should be taken to obtain the correct value in case of non-sinusoidal waveforms
Measuring network for TOUCH CURRENTS
Input resistance: ≥ 1M
Input capacitance: ≤ 200pF
Frequency range: 15Hz to 1MHz and d.c.respectively
=1500Ω
R
S
Fig. 1
R0=500Ω
Fig. 2
C
S
=0.22μF
10k
U
1
F
0.022
V
U2 (V)
3
Prevention of Electrostatic 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 electrostatic 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
aluminum foil, to prevent electrostatic charge build up 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 cond uctive 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. (Otherwise harmless motion such as th e
brushing 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).
There are special components used in this equipment which are important for safety.
These parts are marked by in schematic diagrams, exploded views and replacement parts list. It is essential that
these critical parts should be replaced with manufacturer’s specified parts to prevent shock, fire, or other hazards. Do
not modify the original design without permission of manufacturer.
IMPORTANT SAFETY NOTICE
4
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 laye red boards, please check the component side for excess solder which may
flow onto the opposite side. (see Fig.3)
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. (see Fig.4)
Fig.3
Fig.4
5
Service Hints
How to remove the Pedestal assembly
Lay the main unit face down. (see Fig.5)
Remove the 4 fixing screws and the pedestal assembly. (see Fig.6)
SCREWS
How to remove the backcover
Remove the 10 fixing screws. (see Fig.7)
SCREWS
Fig.5
Fig.6
Fig.7
SCREWS
SCREWS
6
Chassis Board Layout
KEY CONTROL
P-BOARD
Board Name Function
A-Board Main Board
A-Board Tuner
A-Board AV2 Terminal
Key Control Key Control
P-Board Mains Input, Power Switch
P-Board Power Supply
V-Board Remote Receiver, LED IR
Setting Inspection
Voltage Confirmation
A board Normal mode
Test point Position Voltage Description
TP025 C888
TP024 C891
TP031 R874
TP029 C868 +pin
TP030 C864 +pin
TP025 C888 <2V 5V
P board
TP842 Q843
TP840 Connector P2, pin12
TP3802 IC3802, pin1
TP3800 IC3801, pin4
TP3801 IC3801, pin21
TP842 Q843 <10V 24V switched
Confirm the following voltages:
A-BOARD
V-BOARD
5V±0,25V 5V
8,2V±0,5V 8V
30V±2V 30V
Standby mode
3,3V±0,2V STBY3,3V
1,8±0,15 STBY1,8V
Normal mode
23,8V±1V 24V switched
9,8V±1 12V
15V±1V 15V
4,3V±0,3V REG2
4,5V±0,3v REG3
Standby mode
7
Self Check
Self-check is used to automatically check the bus lines and hexadecimal code of the TV set. To enter Self-Check mode, keep
pressing the STATUS button on the remote control and press the down (-/v) button on the TV set. To exit Self Check,
switch off the TV set at the power button.
TX-20LA80F
TX-20LA80FS
E2 O.K.
VCTP O.K.
TUN O.K.
Chassis 22
Model 01
Size 20
VCTP B3
Display Ref. No. Description P.C.B.
E2 IC1120 EAROM A-Board
VCTP IC1501 AUDIO VIDEO TEXT PROCESSOR A-Board
TUN TU001 TUNER A-Board
Panasonic GLP21L
Self Check Complete
E2CRC 9A
OPTION 1 0F
OPTION 2 00
OPTION 3 A0
OPTION 4 11
OPTION 5 00
OPTION 6 05
OPTION 7 DD
OPTION 8 D2
OPTION 9 00
OPTION 10 20
OPTION 11 11
OPTION 12 00
OPTION 13 08
CHECK AD
TV V2.06
E2 V04
If the CCU ports have been checked and found to be incorrect or not located then " - - " will appear in place of "O.K.".
8
Adjustment Method
How to enter Service 1
• Set the Bass to maximum position, set the Treble to minimum position then keep pressing the INDEX button on the
remote control and press the down button (-/v) on the TV set, this will place the TV set into the Service Mode 1.
Key Command
• Press the RED / GREEN buttons to step up / down through the functions.
• Press the YELLOW / BLUE buttons to alter the function values, to alter White Rasters use +/- buttons
• Press the OK button after each adjustment has been made to store the required values.
• To exit the Service Mode, press the "N" button.
Keep adjusting sequence: DVCO, Sub-Contrast, other items.
Item
Sub-Contrast
DVCO
Highlight
Lowlight
Note: All setting values are approximate
High 12 0410 0410 0410
Low 4 0064 0064 0064
Setting indication
Sub-Contrast
32
DVCO
63
Settings / Special features
Receive a 80% white level Philips Pattern with correct
sound system (B/G, D/K) via aerial input. For Sub-
Contrast alignment press "Blue" button, wait until the
figure colour is changed from red to black colour.
Press the OK.
Receive a 80% white level Philips Pattern via aerial
input. For DVCO alignment press "Blue" button, wait
until the figure colour is changed from red to black
colour. Press the OK.
For correct setting see White Balance Adjustment
Sub-Brightness
Sub-Brightness
-5
Optimum setting.
White Balance Adjustment
Instrument
• Remote Control
• LCD WB meter (Minolta CA-210 or equivalent)
Condition
• Switch on the TV Set. Enter Service1. Step down to Highlight line and keep the aging time more than 20 minutes.
Procedure
• After aging time above set White Raster No.12 for Highlight and No.4 for Lowlight Press the OK button
to store.
• Put Minolta Sensor to the center of the LCD Panel with 25mm gap between Minolta Sens or and LCD Panel. Adjust "x"
and "y" values by changing Red and Blue values.
• Press OK button to store setting.
Item Value
Highlight
Lowlight
x
y
x
y
2850±150
2940±150
2860±150
2900±150
High 12
Low 4
9
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