Panasonic TX-20LA5F, TX-20LA5P Service manual

ORDER No. PCZ0506069C2

Service Manual

Colour LCD Television

TX-20LA5F

TX-20LA5P

GLP2N Chassis

SPECIFICATIONS

Power Source: 220-240V AC, 50/60Hz
Power Consumption: 74W
Stand-by Power

Cons

umption: 0,9W
Aerial Impedance: 75Ω unbalanced,
Receiving System: PAL-I, B/G

Receiving Channels:

VHF E2-E12 VHF A-H (ITALY)
VHF H1-H2 (ITALY) UHF E21-E69
VHF R1-R2 VHF R6-R12
VHF R3-R5 CATV (S01-S05)
CATV S1-S10 CATV S11-S20 (U1-U10)
CATV S21-S41 (Hyperband)

Operating Conditions:

Temperature: 5°C ÷ 35
Humidity: 5% ÷ 90

Intermediate Frequency:
Video/Audio

Video
Audio 33,4MHz (B/G),33,16MHz (A2)

Colour 34,47MHz (PAL)

SECAM B/G, D/K, L/L’
PAL-525/60 (AV only)
M.NTSC (AV only)
NTSC (AV o

°C

% RH (non-condensing)

38,9MHz, 33,9MHz

33,05MHz (NICAM B/G, D/K, L)
32,4MHz (D/K),32,66MHz (CZ STEREO)
40,4MHz (L’), 39,75Mhz (L’NICAM)

34,5MHz, 34,65MHz (SECAM)
38,3MHz, 38,15MHz (SECAM L’)

Coaxial Type

, D/K,

nly)

AV1 OUT Video (21 pin) 1V p-p 75Ω

AV2 IN S-Video IN Y: 1V p-p 75Ω

LCD screen: L5EDD5L00

Audio Output: 2x3W RMS

Headphones: 3,5mm, 8Ω Imp
Accessories

supplied : Remote Con

Dimensions:

Including TV stand
Height:
Width: 498mm
Depth: 260mm

TV set only
Height: 450mm
Width: 498mm
Depth: 93mm

Net weight: 7,5kg

Specifications are subject to change w
Weights and dimensions shown are approximate.

Audio (21 pin) 500mV rms 1kΩ

(4-pin) C:0,3V p-p 75Ω
Audio (RCAx2) 500mV rms 10kΩ
Video (RCAx1) 1V p-p 75Ω

005
640 x 480 VGA, 4:3
Visible Diagonal 508mm

4Ω impedance

edance

trol

2 x R6 (UM3) Batteries

505mm

ithout notice.

Terminals:

AV1 IN Video (21 pin) 1V p-p 75Ω

Audio (21 pin) 500mV rms 10kΩ
RGB (21 pin) 0,7V p-p 75Ω

CONTENTS

SAFETY PRECAUTIONS.........................................................................................................................................................2

GENERAL QUIDE LINES....................................................................................................................................................2

TOUCH – CURRENT CHECK
PREVENTION OF ELECTROSTATIC DISCHARGE (ESD) TO ELEC

ABOUT LEAD FREE SOLDER (PBF).......................................................................................................................................4

SUGGESTED PB FREE SOLDER
SERVICE HINT
SETTING INSPECTION

SELF-CHECK ...........................................................................................................................................................................6

ALIGNMENT SE
BLOCK DIAGRAMS
PARTS LOCATI

REPLACEMENT PARTS LIST................................................................................................................................................12

SCHEMATIC DIAGRAMS
CONDUCTOR VIEWS

S ......................................................................................................................................................................5

............................................................................................................................................................6

TTINGS..........................................................................................................................................................7

..................................................................................................................................................................8

ON.................................................................................................................................................................11

.......................................................................................................................................................19

............................................................................................................................................................25

.............................................................................................................................................2

TROSTATICALLY SENSITIVE (ES) DEVICES ...........3

......................................................................................................................................4

SAFETY PRECAUTION

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 leakage current checks to prevent the customer from being exposed to shock
hazards.

4. Always ensure panel TKKL5290 is correctly replaced before returning to customer (see Fig.1).

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 go od 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 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 (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 should
be repaired and rechecked before it is returned to the customer.

2

A

Ω

Ω

Ω

COLD

Ω

WATER PIPE
(EARTH GROUND)

Measuring network for TOUCH CURRENTS

Fig. 2

CS=500µF

10k

U

1

0.022µF

V

U2 (V)

RS=500

TO

PPLIANCES
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

Input resistance: ≥ 1M
Input capacitance: ≤ 200pF
Frequency range: 15Hz to 1Mhz and d.c.respectively

R0=500

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 commerciall y av ailable 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 char ges 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, 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 the
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).

IMPORTANT SAFETY NOTICE

There are special components used in this equipment which are important for safety.
These parts are marked by

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.

in schematic diagrams, exploded views and replacement parts list. It is essential that

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 s
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 so
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 sid e for excess solder which may

flow onto the opposite side. (see Fig.3)

older, and PbF will refer to Lead Free Solder.

lder on the pins or solder area before

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.

Fig.4

4

SERVICE HINTS

HOW TO REMOVE THE BACK COVER

Lay the main unit face down as shown in Fig.5.

Remove the 4 fixing screws as shown in Fig.6.
Remove the stand assembly.

Fig.5

e the 8 fixing screws as shown in Fig.7.

Remov
Remove the back cover.

SCREWS

SCREWS

Fig.6

SCREWS

Fig.7

5

SETTING INSPECTION

A

VOLTAGE CONFIRMATION

Confirm the following voltages:
A board Normal mode Standby mode

Connector A6, pin 1 5,0V ± 0,2V <0,3V
C865, + pin 31V ± 3V <3V
C861, + pin 8V ± 0,4V <0,55V
C862, + pin 2,5V ± 0,2V
C889, + pin 3,3V ± 0,2V
C882, + pin 1,8V ± 0,1V <0,2V

P board

Connector P4, pin 19 23V ± 0,25V 23V ± 0,25V
Connector P4, pin 15 12,5V ± 0,25V
Connector P4, pin 2 1,4V ± 0,1V <0,5V

2,5V ± 0,2V
3,3V ± 0,2V

12,5V ± 0,25V

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 customer controls at the front
the TV set. To exit Self Check, switch off the TV set at the power button.

E2 O.K.
DPS O.K.
VSP O.K.

VSW O.K.
TUN O.K.
MSP O.K.
DPL --­MAS ---

TX-20LA5F TX-20LA5P

OPTION 1 0F 0F
OPTION 2 00 00
OPTION 3 A0 A0
OPTION 4 11 11
OPTION 5 00 00
OPTION 6 15 15
OPTION 7 FD FD
OPTION 8 D0 50
OPTION 9 00 00
OPTION 10 80 80
OPTION 11 1B 1B
OPTION 12 00 00
OPTION 13 0C 0C

CHECK 49 C9

If the CCU ports have been checked and found to be incorrect or not located then " - - " will appear in place of "O.K.".

6

Display Ref. No. Description P.C.B.

E2 IC1101 EAROM A-Board

DPS IC1700 DISPLAY PROCESSOR AND SCALER A-Board

VSP IC1500 VIDEOSIGNAL PROCESSOR A-Board

AVSW IC1500 AV SWITCH A-Board

TUN TNR001 TUNER B-Board
MSP IC2000 MULTISTANDART SOUND PROCESSOR A-Board

DPL --- DOLBY PROLOGIC PROCESSOR ---

MAS --- MPEG1 AUDIO PROCESSOR ---

ALIGNMENT SETTINGS

(The figures below are nominal and used for representative purposes only.)

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 customer controls at the front of the TV, this will place the TV into
the Service Mode 1.

2. Press the RED / GREEN buttons to step up / down through the functions.

3. Press the YELLOW / BLUE buttons to alter the function values.

4. Press the OK button after each adjustment has been made to store the required values.

5. To exit the Service Mode, press the "N" button.

Alignment Function

Horizontal Position

Vertical Position

DVCO

Highlight

Lowlight

Sub-Brightness

Setting indication

Note: All setting val

H-Pos

V-Pos

DVCO

High 0885 0851 0954
Low 0060 0096 0062

Sub-Brightness

ues are approximate

0

0

3

0

Settings / Special features

Optimum setting.

Optimum setting.

Receive a PAL Colour Bar Pattern. For

DVCO ali

until the figure colour is changed from red

gnment press "Blue" button, wait

to black colour.

Optimum setting.

Optimum setting.

7

R

L

3

4

1

2

Z2

13

14

17

TUNER

R2351

R2350

45

17623

R

L

HEADPH

JK2350

B - BOARD

B1

A12

SDA5550M

IC1100

21 TXT CVBS

57 OSD R

58 OSD G

59 OSD B

Q1500

Q1502

8

9

11

8

9

11

Q202Q201

61 TXT CVBS
52 TVCVBS

AD_656.0 ÷ AD_656.7

Z - BOARD

IC1500

VSP9405BVKC4

Z1

A2

4

L OUT

1 L IN

AV1CVBS 53

AV1 V OUT 63

R EXT 39
G EXT 40

B EXT 41

AV2 V
AV2 Y

AV2 C 56

3

3

57
55

IC250

TDA1517N3

5

5

R OUT 6

9 R IN

20 VIDEO IN
19 VIDEO OUT
15 R IN
11 G IN

7 B IN

6 L IN
3 L OUT

AV1 21 PIN SCART

IC2000

MSP3410GAB83

SPK L OUT 28

SPK R OUT 27

AV1 L IN 56

AV1 L OUT 37

AV1 R IN 57

AV1 R OUT 36

AV2 R IN 51
AV2 L IN 50

60 AM IN

AD_656.7

OSD R IN1 131

OSD B IN1 133

OSD G IN1 132

AD_656.0

VIDEO & STEREO AUDIO BLOCK DIAGRAM

48 TX0-

IC1701

LVDS DRIVER

47 TX0+

46 TX1-

DPS9450A

IC1700

B1.0 ÷ B1.7

B1.7

B1.0

45 TX1+

42 TX2-

R1.0 ÷ R1.7

G1.0 ÷ G1.7

G1.7

R1.7

R1.0

G1.0

41 TX2+

38 TX3-

37 TX3+

67 SIF

A - BOARD

9

3

1

11

13

15

17

19

A50

TO LCD PANEL

8

2 R IN
1 R OUT

JK3000

R

L

V

Y
C

AV2 terminal

r

r

SERVICE

Y

Y

A6

1

33V

5,0V

IC250

IC1103

IC1102

2,5V_SB

2,5V_A_SBY

LC filter

2

REG

IC862

1

LVDS DRIVER

1,9,26,34,44

LC filter

3,3V_SB

3,3V_LVDS

3,3V_LVDS

3,3V

3,3V_D_SBY

4

REG

IC866

1

A - BOARD

IC1701

LCD PANEL

5V

5V

6

REG

IC883

1

IC1104

IC1105

IC860

Q868

5

A4

1

24V_INV

DPS_1,8DIG

24,62,91,118

DPS_3,3ANA

129,139

DPS_1,8ANA

75,134,143

5V

A50

5,0V

IC1700

DPS9450A

2

4

Q1700

8V

5

DPS_3,3DIG

REG

IC871

4

5,20,32,40,48,57,68,78,86,96,104,112,123

SBY3,3V

RESET IC

RESET IC

33V

REG

Q867

354

SBY3,3V_D

2

24V

2

24V

12V

24V_INV

Q866

12V

7

TDA1517

SBY2,5V_D

6,73

IC2000

SBY3,3V_D

32,1

EPROM

32

SDRAM

3,3V

2,5V_D_SBY

LC filter

LC filter

SBY3,3V_D

Q890

IC1100

3,3V_A

3,3V_D

LC filter

LC filter

SDA5550M

8,40,75,92

22,56

1,8V

Q880

SBY3,3V_D

1,8V_A

LC filter

SBY2,5V_A

IC1101

1,8V_D

LC filter

IC1500

11,12,13,65,66

MSP3410

39

8

EAROM

VSP9405

5,0V

8,0V

SBY3,3V_D

1,8V_VSP

68

1,8V_D

5,28,34,66

3,3V_D

7,12,25,72

1,8V_A

35,42,50,64

F861

3,3V_A

24V

3

4

10

A12

A3

3

5

1

A13

1,44,59,75,78

B1

33V

10

33V

4

5V

5V

V1

3

SBY3,3V

P4

19
17

24V

P - BOARD

D851

V - BOARD

REMOTE

RM1050

SN1063

CC

LF803

LF802

Line

Line

+

D801

-

Filte

Filte

POWER SUPPLY BLOCK DIAGRAM

3

15

TUNER

B - BOARD

SW800

F800

16 4
15

A

REG

D852

T801

D853

7

14

6

8

13

1

3

4

Q805

Q803

20

23

POWER

SUPPLY

IC801

IC850

K

IC803

16

19

15

11

IC802

7

10

Q851

4

1

P1

MAINS IN

9