Panasonic TX-21RX20T Schematic

Colour Television

TX-21RX20T

GP41Z Chassis

ORDER NO. MTV0801643CE

Specifications

Power Source : AC SINGLE 220-240 V, 50/60 Hz

Power Consumption : 86 W

Aerial Impedance : 75 Ω unbalanced

Coaxial type

Receiving System : 17 Systems

SYSTEMS FUNCTIONS

———————————————————————————————

1 PAL B, G, H

2 PAL I Reception

3 PAL D, K

4 SECAM B, G

5 SECAM D, K

6 SECAM K1

7 NTSC M

(NTSC 3.58 / 4.5 MHz)

———————————————————————————————

8 NTSC 4.43 / 5.5 MHz

9 NTSC 4.43 / 6.0 MHz

10 NTSC 4.43 / 6.5 MHz

11 NTSC 3.58 / 5.5 MHz Playback from

12 NTSC 3.58 / 6.0 MHz

13 NTSC 3.58 / 6.5 MHz

14 SECAM I

———————————————————————————————

15 PAL 60 Hz / 5.5 MHz Playback from

16 PAL 60 Hz / 6.0 MHz

17 PAL 60 Hz / 6.5 MHz

of broadcast

transmission and

playback from

video cassette tape

recorders.

special VCR only.

special Disc player

and VCR only.

Receiving Channels :

VHF 2-12 PAL / SECAM B, K1

0-12 PAL B (AUST)

1-9 PAL B (N. ZEALAND)

1-12 PAL / SECAM D

1-12 NTSC M (JAPAN)

2-13 NTSC M (U.S.A.)

UHF 21-69PALG,H,I/SECAMG,K,K1

28-69 PAL B (AUST)

13-57 PAL D, K

13-62 NTSC M (JAPAN)

14-69 NTSC M (U.S.A.)

CATV S1-S20 (OSCAR)

1-125 (U.S.A. CATV)

C13-C49 (JAPAN)

S21-S41 (HYPER)

Z1-Z37 (CHINA)

5A, 9A (AUST)

Tuning System : Frequency synthesizer

Auto search tuning : 100 position

TX-21RX20T

Video / Audio Terminal :

DVD

Y 1.0 Vp-p 75 Ω

V1,2,3

Video In 1Vp-p75Ω

Audio In Approx. 0.5 V, 47 kΩ

Monitor Out

Video Out 1Vp-p75Ω

Audio Out Approx. 0.5 V, 1 kΩ

Picture Tube : Viewable Picture tube measured

0.7 Vp-p 75 Ω

diagonally : 51 cm

Measured diagonally,

Audio Output : 10 W x 2 = 20 W

Operating Conditions :

Temperature : 0°C - 35°C

Humidity : 20°C - 80°C RH (non-condensing)

Dimensions : Height : 431 mm

Mass : 20.5 kg (Net)

Specifications are subject to change without notice. Mass and dimensions shown are approximate.

90° deflection

Width : 596 mm

Depth : 340 mm

CONTENTS

Page Page

1 Safety Precautions

1.1. General Guidelines

1.2. Leakage Current Cold Check

1.3. Leakage Current Hot Check (Fig. 1)

1.4. X-Radiation

1.5. SW-Board Fix to Cabinet

1.6. GP41Z Chassis Block Diagram

2 Service Hints

2.1. Service Position for E-Board

2.2. Service Mode Explanation

2.3. Adjustment for White Balance

2.4. Adjustment for CRT CUT OFF

2.5. Adjustment Procedure

2.6. Adjustment of Purity

3 Location of Lead Wiring

3.1. Wire Dressing

3.2. Wire Dressing and Connections

4 Conductor Views

5 Schematic Diagram

5.1. A Board

5.2. L Board

5.3. V Board

5.4. G Board

5.5. P Board

5.6. K Board

5.7. SW Board

6 Parts Locations

6.1. Packing Exploded View - A

6.2. Packing Exploded View - B

6.3. Parts Locations

7 Replacement Parts List

7.1. Replacement Parts List

TX-21RX20T

1 Safety Precautions

1.1. General Guidelines

1. It is advisable to insert an isolation transformer in the AC supply before servicing this hot chassis.

2. When servicing, observe the original lead dress, especially the lead dress in the high voltage circuits. If a short circuit is found, replace all parts which have been overheated or damaged by the short circuit.

3. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers, shields and isolation R-C combinations are properly installed.

4. When the receiver is not to be used for a long period of time, unplug the power cord from the AC power socket.

5. Potential, as high as 25.0 kV is present when this receiver is in operation. Operation of the receiver without the rear cover involves the danger of a shock hazard from the receiver power supply. Servicing should not be attempted by anyone who is not thoroughly familiar with the precautions necessary when working on high voltage equipment. Always discharge the anode of the picture tube to the receiver chassis before handling the tube. After servicing, make the following leakage current check to prevent the customer from being exposed to shock hazards.

1.2. Leakage Current Cold Check

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

2. Turn on the receiver’s power switch. Measure the resistance value, with an ohmmeter, between the jumper and each exposed metallic cabinet part on the receiver, such as screw heads, aerials, connectors, control shafts, etc. When the exposed metallic part has a return path to the chassis, the reading should be between 4 MΩ and 20 MΩ. When the exposed metal does not have a return path to the chassis, the reading must be infinite.

1.3. Leakage Current Hot Check (Fig. 1)

1. Plug the power cord directly into the power socket. Do not use an isolation transformer for this check.

2. Check that a 2 kΩ non-inductive resistor and an AC/DC current meter are in series with each exposed metallic part on the receiver in turn and an earth such as a water pipe.

The current from any point should not exceed 0.7 mA peak AC or 2 mA DC. In the case of a measurement being outside of these limits specified, there is a possibility of a shock hazard and the receiver should be repaired and rechecked before it is returned to the customer.

Fig. 1

TX-21RX20T

1.4. X-Radiation

Warning:

The potential sources of X-Radiation in TV set are the EHT section and the picture tube. When using a picture tube test jig for service, ensure that the jig is capable of handling 25.5 kV without causing X-Radiation.

Note: It is important to use an accurate periodically calibrated high voltage meter.

1. Set the brightness to minimum.

2. Use the remote to get into Service Mode.

3. Measure the EHT. The meter reading should indicate 24.0 ± 1.5 kV. If the meter indication is out of tolerance, immediate service and correction are required to prevent the possibility of premature component failure.

4. To prevent the possibility of X-Radiation, it is essential to use the specified picture tube, if service replacement becomes necessary.

1.5. SW-Board Fix to Cabinet

1.6. GP41Z Chassis Block Diagram

CRT

coil

defl.

CRT

DRIVE

TX-21RX20T

PIP MODEL

IC1101

EEPROM

SCL

SDA

PVP

SPEAKER

R/G/B

IC1801

CVBS IN

SCL SDA

R/G/B

CVBS OUT

AMP

IC2301

AUDIO

IC601

VCT-IF

OUT

AUDIO

V_IN

REAR INPUTS

AV1 : V/L/R

GEO

A_IN

MON_OUT

V/L/R

MON_OUT

AV3 : YUV/V/L/R

V OUT

H OUT

TUNER

GEOMAGNETIC

LINE FILTER

REMOTE RECEIVER

ONLY FOR MODEL WITH

5TH HARMONIC COIL

LED

MAIN

POWER

SWITCH

AV2 : V/L/R

SIDE INPUTS

PANEL KEY

TX-21RX20T

2 Service Hints

2.1. Service Position for E-Board

1. Remove the back cover.

2. Stand the TV set as shown in Fig. 2.

3. Remove the A-Board from the TV set by pulling the main board out as shown in Fig. 2.

Fig. 2

2.2. Service Mode Explanation

1. Service Mode Access

a) Set the timer ON.

b) Press remote’s RECALL (

2. Service Mode 1 Controls

3. Service Mode 2 Controls

To enter SERVICE 2; press channel key ‘1’ in SERVICE 1 entry screen.

) and panel’s volume down key simultaneously to enter SERVICE 1.

Key 3/4 Previous/Next Service 1 Item Key 8/9 Adjust user Brightness (-/+) Program up/down Program position up/down Volume + Increment of selected item Volume - Decrement of selected item OK Store/Save selected item Normalize Exit service mode

Key 3/4 Previous/Next Service 2 Item Key 8/9 Toggle for option bit 0-7 Program up/down Program position up/down Volume + Increment of selected item Volume - Decrement of selected item OK Store/Save selected item Normalize Exit service mode

NOTE:- Service Mode 2 options bit refer to each model front cover spec.

4. Service Mode 3 Controls

To enter SERVICE 3; press channel key ‘1’ in SERVICE 2 entry screen.

Key 3/4 Previous/Next Service 1 Item Program up/down Program position up/down Volume + Increment of selected item Volume - Decrement of selected item OK Store/Save selected item Normalize Exit service mode

2.3. Adjustment for White Balance

Preparation:

1. Receive the white balance pattern and aging should be performed over 30 minutes.

2. Set the picture menu to DYNAMIC NORMAL.

3. Degausse the CRT face.

4. Fix the CRT colour analyzer receiver unit to CRT face.

Adjustment of Low Light

1. Adjustment Sub Bright, so that Y = 6.5 ± 1.0 nit.

2. Adjustment R-CUT OFF, so that X = 0.241 ± 0.005 nit.

3. Adjustment G-CUT OFF, so that Y = 0.242 ± 0.005 nit.

Adjustment of High Light

1. Adjustment Sub Bright, so that Y = 150 nit.

2. Adjustment R-Drive, so that X = 0.263 ± 0.003 nit.

3. Adjustment B-Drive, so that Y = 0.261 ± 0.003 nit.

TX-21RX20T

2.4. Adjustment for CRT CUT OFF

Preparation:

1. Connect the oscilloscope probe to TPL5.

2. Screen VR min.

3. Set the data Sub Bright, Bright.

4. In service Mode at “Bright” dac press [5] in factory mode to enter vertical line and adjust by volume down or up button.

5. Adjust “Screen VR” until 1-H Line appears.

2.5. Adjustment Procedure

2.5.1. +B Voltage

Item / preparation

1. Operate the TV set.

2. Set control as follows :

Brightness ........... minimum

Contrast ............... minimum

Adjustment procedure

1. Confirm the DC voltage at the indicated test points, as follows :

TPA 15 : 3.35 ± 0.2 V

TPA 16 : 130 ± 2 V

TPA 17 : 8.25 ± 0.35 V

TPA 18 : 1.85 ± 0.15 V

TPA 19 : 5.30 ± 0.2 V

TPA 20 : 188 ± 15 V

TX-21RX20T

2.5.2. High Voltage

Item / preparation

1. Receive the crosshatch pattern.

2. Set to 0 Beam.

Screen VR .......... minimum

Contrast .............. minimum

Adjustment procedure

1. Connect a DC voltage meter to TPA 16 and confirm the +B voltage is 130.0 V ± 2.

2. Connect a high frequency voltmeter to heater and confirm that voltage reads 6.3 V (RMS) ± 0.24.

3. Normalize the brightness and contrast.

2.6. Adjustment of Purity

1. INSTRUMENTS

a. Purity Jig

b. Helmhortz device

2. PREPARATION

a. Set the Helmhortz device to local magnetic field.

Horizontal : 0 ± 0.03 × 10-4T

b. Aging should be performed over 60 minutes.

c. Receive the purity pattern (White pattern).

d. Picture menu : CONTRAST ... Max. BRIGHT ... Max.

e. Set V-CENTER to [4].

f. Static convergence should have been roughly adjusted.

g. Connect DC current meter through FBT (pin 3) and adjust to [1200 ± 10%] µA.

3. ADJUSTMENT

a. Set both purity magnets’ knobs to top.

b. Adjust the purity so that the markers on monitor scope of purity jig become symmetrical in horizontal direction.

c. Only for stripe CRT, correct vertical centre by purity magnet too.

d. Set up deflection yoke so that the position of deflection yoke becomes [10 µm ± 5] forward on monitor scope at this time by

attention note to tile deflection yoke.

e. Repeat procedures (a) ~ (d).

f. Tighten deflection yoke band.

g. Adjust beam landing by microscope. (Only for model change or check instruments)

ADJUSTMENT OF CONVERGENCE

1. INSTRUMENT

a. Helmhortz device

2. PREPARATION

a. Set the Helmhortz device to local magnetic field.

Horizontal : 0 ± 0.03 × 10-4T

b. Receive the crosshatch pattern.

c. Picture menu : DYNAMIC Normal and adjust BRIGHT DAC until gray portion of crosshatch.

d. Set DY to CRT not to tilt (up and down and left right).

3. ADJUSTMENT

a. Static Convergence Adjustment

a. Make sure that the magnets are positioned as shown as in Fig. 1.

b. Adjust the 4-pole magnets (Fig. 1) to align centre dots of R and B adjust 6-pole magnets to align centre dots to G.

c. After adjustment, secure magnets with magnet lock of white lacquer.

• Beams move with rotating when static magnet is turned. Rotational reduce of beams differs by angle of two magnets. Therefore, repeat magnet adjustment several times so that all are aligned completely.

b. YHC, YV, XV Adjustment (Fig. 2)

a. Adjust that static and Dynamic convergence is best with YHC VR, YV VR and XV coil. In case static convergence is

tilted, repeat (1) Static Convergence Adjustment.

c. Dynamic Convergence Adjustment

a. When dynamic convergence is bad, fix permalloy between neck and DY so that dynamic convergence best.

TX-21RX20T

Fig. 1

4. CONFIRM THAT LEFT UPPER SIDE LINE IS STRAIGHT.

When left upper side line is not straight, put magnet on DY and adjust the left upper side line so it is straight.

Fig. 2

TX-21RX20T

ADJUSTMENT OF CRT VRS

1. PREPARATION

a. Set DY to CRT not to tilt up and down left and right deflection. (Fig. 1)

b. Set CY to CRT and set CY magnet primarily.

Pur Mg : Set Pur Mg so that 2 magnets are horizontal position.

VRS Mag : Set VRS Mg so that 2 magnets are top position.

c. Set geomagnetic correction DAC. As in TABLE 1.

2. ADJUSTMENT

a. Receive the white balance pattern.

b. Adjust V-CENTER.

c. Set R,B CUT OFF to minimum, and set G CUT OFF to centre.

d. Receive the aging pattern.

e. Set 2 magnets of vertical position to up and down equally so that centre part of CRT. (Fig. 2)

MANUAL

DAC 0

TABLE 1

Fig. 1

Fig. 2

TERRESTRIAL MAGNETISM CIRCUIT CONFIRMATION

1. CONFIRMATION OF GEOMAGNETIC CIRCUIT

a. Select GEOMAGNETIC mode in PRESET MENU.

b. Confirm that it leans right side as shown (Fig. 1), when change the DAC (*).

c. Confirm that it leans left side as shown (Fig. 1), when change the DAC (**).

d. Confirm that purity is changed, when changing the DAC.

e. Set Geomagnetic DAC as in TABLE 1.

TX-21RX20T

Fig. 1

MANUAL

DAC 0

TABLE 1

MANUAL

*DAC -1 ~ -8

**DAC +1 ~ +8

TABLE 2

TX-21RX20T

FOCUS ADJUSTMENT

1. PREPARATION

a. Receive crosshatch pattern E-4

b. Picture menu : DYNAMIC NORMAL

2. ADJUSTMENT

a. Adjust focus VR for best position.

Adjust focus base on no. 6 line

Fig. 1. Crosshatch Pattern

DEFLECTION

Note:- For Philippines model, all 50 Hz adjustment is made in AV mode.

A . DEFLECTION ADJUSTMENT / CONFIRMATION (50 Hz, 4:3 Mode ONLY)

(Service 1)

1. INSTRUMENT

a. Helmhortz device

2. PREPARATION

a. Set the Helmhortz device to local magnetic field.

b. Picture menu : DYNAMIC Normal

3. CONFIRMATION AND ADJUSTMENT

a. Adjustment of 50 Hz V-CENTER

a. Receive the monoscope pattern (E11).

b. Adjust V-POS so that centre of monoscope pattern is at CRT centre.

TX-21RX20T

b. Adjustment of 50 Hz V-AMP

a. Receive the monoscope pattern (E11).

b. Adjust V-AMP so that

C, D (Fig. 3) is 2.0 ± 0.1

A, B (Fig. 3) is 2.0 ± 0.1

c. Adjustment of 50 Hz H-CENTER

a. Receive the monoscope pattern (E11).

b. Adjust H-POS so that horizontal position is at centre of CRT.

Fig. 3

TX-21RX20T

B . DEFLECTION ADJUSTMENT / CONFIRMATION (50 Hz, 4:3 Mode ONLY)

(Service 1)

1. INSTRUMENT

a. Helmhortz device

2. PREPARATION

a. Set the Helmhortz device to local magnetic field.

b. Picture menu : DYNAMIC Normal

3. CONFIRMATION AND ADJUSTMENT

a. Adjustment of 50 Hz V-CENTER

a. Receive the Philips pattern (US11).

b. Adjust V-POS so that centre of Philips pattern is at 2/3 of Top and Bottom.

A, B (Fig. 3c) is 2/3 of viewable size

b. Adjustment of 50 Hz V-AMP

a. Receive the Philips pattern (US11).

b. Adjust V-AMP so that

A (Fig. 3b) is 2/3 of viewable size

c. Adjustment of 50 Hz H-CENTER

a. Receive the Philips pattern (US11).

b. Adjust H-POS so that horizontal position is at centre of CRT.

C, D (Fig. 3c) is 2/3 of viewable size

Fig. 3b

Fig. 3c

4. ADJUSTMENT OF 50 Hz H-AMP

a. Receive the monoscope pattern (E11).

b. Adjust H-AMP so that both edges are within 2.5 ± 0.2. Refer to Fig. 1.

Fig. 1

5. EW ADJUSTMENT / CONFIRMATION

a. PREPARATION

a. Receive crosshatch pattern (E4).

b. EW ADJUSTMENT

a. Adjust the vertical line no. 2 to straight line (parabola) by EW-AMP 1. (Refer to Fig. 1c)

TX-21RX20T

Fig. 1c

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