Panasonic TX-23LX50M, TX-23LX50A, TX-23LX50X Service manual

GLP2W Chassis

ORDER NO. ITD0505026CE

LCD TV

Specifications

PowerSource

PowerConsumption

LCD 22.9 - inch (58.3 cm)

Screen Size 508 mm (W) × 286 mm (H) (20.0” × 11.3”)

Sound

Speake

Audio Output 6 W (3 W + 3 W), 10 % THD

Headphones M3 (3.5 mm) Jack × 1

Receiving Systems/Band name

C 110-240 V, 50/60 Hz

verage use : 87 W

Standbycondition : 0.5 W

Wide XGA (1366 × 768 pixels) 16:9 aspect ratio LCD panel.

Ø6 cm × 2 pcs, 8 W

Receiving Channels RegularTV

TX-23LX50M / TX-23LX50A / TX-23LX50X

Aerial-Rea

Operating Conditions Temperature:5°C-40°C

Connection Terminals

AV1 VIDEO (RCA Pin Type) 1.0 Vp-p (75 W)

AV2 VIDEO (RCA Pin Type) 1.0 Vp-p (75 W)

MONITOR OUT VIDEO (RCA Pin Type) 1.0 Vp-p (75 W)

Dimensions ( W × H × D )

Including TV Stand 612 mm × 505 mm × 259 mm (24.1” × 19.9” × 10.2”)

TV Set Only 612 mm × 441 mm × 125 mm (24.1” × 17.4” × 4.9”)

Weight 10.0 kg (22.0 lb.) Net

HF BAND 2-12 (PAL/SECAM B, K1)

0-12 (PAL B AUST.)

1-9 (PAL B N.Z.)

1-12 (PAL / SECAM D)

1-12 (NTSC M Japan)

2-13 (NTSC M USA)

UHF BAND 21-69 (PAL G, H, I / SECAM G, K, K1)

28-69 (PAL B AUST.)

13-57 (PAL D, K)

13-62 (NTSC M Japan)

14-69 (NTSC M USA)

CAT

UHF/ VHF

Humidity: 5 % - 90 % RH (non-condensing)

S-VIDEO (MINI DIN 4-pin) Y: 1.0 Vp-p (75 W ), C: 0.286 Vp-p (75 W)

UDIO L-R (RCA Pin Type × 2) 0.5 Vrms

PB/P

pplicable signal to AV2 Y, P

UDIO L-R (RCA Pin Type × 2) 0.5 Vrms

CB,P

S1-S20 (OSCAR)

1-125 (USA CATV)

C13-C49 (JAPAN)

S21-S41 (HYPER)

Z1-Z37 (CHINA)

5A, 9A (AUST.)

1.0 Vp-p (including synchronization)

± 0.35 Vp-p

CRinputterminals: 525i / p and 625i / p

Note:

Design and specifications are subject to change without notice. Weight and Dimensions shown are approximate.

CONTENTS

Page Page

1 Safety Precautions 4

1.1. General Guidelines

2 Prevention of Electro Static Discharge (ESD) to

Electrostatically Sensitive (ES) Devices

3 About lead free solder (PbF)

4 Self-check function

4.1. How to access

4.2. Screen display

5 Chassis Board Layout

6 Disassembly for Service

6.1. Pedestal ass 馳

6.2. Rear cover

6.3. Tuner cover and the Shield cover

6.4. Power unit

TX-23LX50M / TX-23LX50A / TX-23LX50X

6.5. A-Board 9

6.6. AP-Board

6.7. K-Board

6.8. V-Board

6.9. Speaker

6.10. Main chassis

6.11. LCD Panel

7 Lead of Wiring

8 Service Mode Function

8.1. How to enter SERVICE 1

8.2. How to enter SERVICE 2

8.3. Option Description

8.4. Option Code Setting

9 Adjustment

9.1. DVCO adjustment

10 Conductor Views

10.1. A-Board

10.2. AP-Board

10.3. K and V-Board

11 Block and Schematic Diagram

11.1. Schematic Diagram Notes

11.2. Main Block Diagram

11.3. Power Block Diagram

11.4. Signal Block Diagram

11.5. A-Board (1 of 3) Schematic Diagram

11.6. A-Board (2 of 3) Schematic Diagram

11.7. A-Board (3 of 3) Schematic Diagram

11.8. AP, K and V-Board Schematic Diagram

12 Parts Location & Mechanical Replacement Parts List

12.1. Parts Location

12.2. Packing Exploded Views

12.3. Mechanical Replacement Parts List

13 Electrical Replacement Parts List

13.1. Replacement Parts List Notes

13.2. Electrical Replacement Parts List

TX-23LX50M / TX-23LX50A / TX-23LX50X

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.

1.1.1. Leakage Current Cold Check

1. Unplug the AC cord and connect a jumper between the two prongs on the plug.

2. Measure the resistance value, with an ohmmeter, between the jumpered AC plug and each exposed metallic cabinet part on the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the chassis, the reading should be between 1MW and 5.2MW.

When the exposed metal does not have a return path to the chassis, the reading must be

Figure 1

1.1.2. Leakage Current Hot Check (See Figure 1.)

1. Plug the AC cord directly into the AC outlet. Do not use an

isolation transformer for this check.

2. Connect a 1.5kW, 10 watts resistor, in parallel with a 0.15µF

capacitors, 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 an AC voltmeter, with 1000 ohms/volt or more

sensitivity, to measure the potential across the resistor.

4. Check each exposed metallic part, and measure the

voltage at each point.

5. Reverse the AC plug in the AC outlet and repeat each of the

above measurements.

6. The potential at any point should not exceed 0.75 volts

RMS. A leakage current tester (Simpson Model 229 or equivalent) may be used to make the hot checks, leakage current must not exceed 1/2 milliamp. In case a measurement is outside 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 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 alminum 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.

TX-23LX50M / TX-23LX50A / TX-23LX50X

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 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).

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

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)

stamped on the back of PCB.

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.

TX-23LX50M / TX-23LX50A / TX-23LX50X

4 Self-check function

When phenomena like "the power fails from time to time" or "the video/audio fails from time to time" can not be confirmed at the time of servicing, the self-check function can be used to confirm the occurrence and to limit the scope for the defective circuits.Also, when "the power fails from time to time", display on the screen can be used to confirm the occurrence and to limit the scope for the defective circuits.

Any programmed channels, channels caption data and some other user defined settings will be erased and return to factory setting.

4.1. How to access

4.1.1. Access

Produce TV reception screen and, while pressing [VOLUME-] button on the main unit, press [OFF TIMER] button on the remote controller unit simultaneously.

4.1.2. Exit

When one of the buttons for channel selection etc. is pressed, the display returns to the normal screen.

4.2. Screen display

Display Ref No. Description P.C.B E2 IC1101 EEPROM A-Board DPS IC1700 LCD DRIVER A-Board VSP IC1500 Video Signal Processor A-Board Tun TU100 Tuner A-Board MSP IC2501 Multi Sound Processor A-Board

5 Chassis Board Layout

TX-23LX50M / TX-23LX50A / TX-23LX50X

Board Name Function

A-Board Main (AV connector, AV Switch, Tuner, Audio & Video Processor, MCU,

V-Board Remote Receiver, LED, Speaker Out K-Board Power Switch, Key Scan AP-Board Power Supply, Power Regulator Power Unit Power (AC/DC)

LCD Driver, LVDS)

None serviceable. Power Unit should be exchanged for service.

TX-23LX50M / TX-23LX50A / TX-23LX50X

6 Disassembly for Service

6.1. Pedestal ass’y

1. Lay down the main unit so that the rear cover faces upward.

2. Remove the fixing screw (1pcs

3. Remove the hinge cover.

4. Remove the fixing screws (4pcs ).

5. Remove the pedestal ass´y.

6.2. Rear cover

1. Remove the fixing screws (15pcs and 2pcs ).

2. Remove the rear cover.

6.3. Tuner cover and the Shield cover

1. Remove the AC cord.

2. Remove the fixing screws (2pcs

3. Remove the tuner cover.

4. Remove the fixing screws (5pcs

5. Remove the Shield cover.

TX-23LX50M / TX-23LX50A / TX-23LX50X

6.4. Power unit

1. Disconnect the couplers (P1 and P2).

2. Remove the fixing screws (5pcs

3. Remove the power unit.

6.5. A-Board

1. Remove the fixing screws (4pcs ).

2. Disconnect the couplers (A2 and A5).

3. Disconnect the bridge connector (A3 and A4).

4. Remove the A-Board and the shield case.

6.6. AP-Board

1. Disconnect the couplers (AP1, AP2 and AP5).

2. Disconnect the bridge connector (A3 and A4 on A-Board).

3. Remove the AP-Board.

6.7. K-Board

1. Remove the fixing screws (2pcs and 2pcs ).

2. Remove the K-Board unit.

3. Disconnect the couplers (K1, K2 and K3).

4. Remove the K-Board.

TX-23LX50M / TX-23LX50A / TX-23LX50X

6.8. V-Board

1. Remove the fixing screws (2pcs ).

2. Disconnect the couplers (V1 and V2).

3. Remove the V-Board.

6.10. Main chassis

1. Remove the fixing screw (1pcs ).

2. Disconnect the earth cable.

3. Remove the fixing screws (6pcs

4. Disconnect the couplers (A2, A5, AP2, AP5, CN101 and

K1)

5. Remove the main chassis.

6.9. Speaker

1. Remove the fixing screws (8pcs ).

2. Remove the speaker.

6.11. LCD Panel

1. Remove the main chassis.

2. Remove the K-Board.

3. Remove the fixing screws (2pcs

4. Remove two LCD mount metal.

5. Remove the LCD Panel.

, 5pcs and 1pcs

7 Lead of Wiring

TX-23LX50M / TX-23LX50A / TX-23LX50X

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 1

1. In sound menu, set BASS to MAXIMUM, and set TREBLE to MINIMUM.

2. Simultaneously press INDEX button on remote control and DOWN button [

8.2. How to enter SERVICE 2

1. Set the channel to CH99.

2. Select the “Sub-Brightness” under Service 1.

3. Press HOLD button on remote control.

Note:

To exit to Service mode, press N button on remote control.

] on the TV set.

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