Panasonic TX 28MD4 Service Manual

TX-28/25/21MD4 Service Manual
Safety
Specifications
Parts List
Service
Information
Adjustments
Self Check
Service Hints
Mechanical
View
Disassembly
Location of
Controls
Waveforms
Supplementary Information
Block Diagrams
Schematic Diagrams
PCB Views
Service Support
Service and repair of this product is supported by Panasonic's LUCI interface.
This interface provides a link between the TV and a standard PC to allow a number of diagnostic and control functions to be performed.
For more details contact your local Panasonic company.
BACK
EXIT
Audio
Control
Power supply
Video
BACK
E - PCB Y - PCBs
BACK
E - Schematics H - Schematic
Y - Schematics
BACK
SPECIFICATIONS
(Information in brackets { } refers to model TX-25MD4) (Information in brackets [ ] refers to model TX-21MD4)
Power Source: 220-240V AC, 50Hz Power Consumption: 85W [71W] Aerial Impedance: 75 unbalanced, Coaxial Type Stand-by Power
Consumption: 1,8W Receiving System: PAL I, PAL 525/60
M.NTSC NTSC (AV only)
Receiving Channels: UHF E21 - E69
Intermediate Frequency:
Video 39,5MHz Audio 33,5MHz, 32,95MHz Colour 35,07MHz (PAL)
Video/Audio Terminals:
AUDIO MONITOR OUT Audio (RCAx2) 500mV rms 1k AV1 IN Video (21 pin) 1V p-p 75
Audio (21 pin) 500mV rms 10k RGB (21 pin)
AV1 OUT Video (21 pin) 1V p-p 75
Audio (21 pin) 500mV rms 1k
ORDER No. SM-98017
Colour Television
TX-28MD4 TX-25MD4 TX-21MD4
EURO4 Chassis
AV2 IN Video (21 pin) 1V p-p 75
Audio (21 pin) 500mV rms 10k S-Video IN Y: 1V p-p 75 (21-pin) C:0.3V p-p 75
AV2 OUT Video (21 pin) 1Vp-p 75
Audio (21 pin) 500mV rms 1k Selectable output (21 pin)
AV3 IN Audio (RCAx2) 500mV rms 10k
Video (RCAx1) 1V p-p 75
High Voltage: 28,5kV ±1kV {28,2kV ±1kV}
[28kV ±1kV]
Picture Tube: A66ECF50X41 66cm
{A59ECF50X41 59cm} [A51ECQ51X01 51cm]
Audio Output: 2 x 15W (Music Power)
8 Impedance
Headphones: 8 Impedance
3,5 mm
Accessories supplied : Remote Control
2 x R6 (UM3) Batteries TV Stand
Dimensions:
Height: 580 mm {531 mm} [478 mm] Width: 666 mm {601 mm} [525 mm] Depth: 472 mm {439 mm} [480 mm]
Net weight: 31kg {25kg} [22kg] Specifications are subject to change without notice.
Weights and dimensions shown are approximate.
3DQDVRQLF
NOTE: This Service Manual should be used in conjunction with the EURO4 Technical guide.
Panasonic CS ( U.K. ) Ltd.
WILLOUGHBY ROAD,
BRACKNELL,
BERKS.,
RG12 8FT.
CONTENTS
SAFETY PRECAUTIONS..........................................................................................................................................................2
SERVICE HINTS.......................................................................................................................................................................3
SERVICE POSITION.................................................................................................................................................................4
ADJUSTMENT PROCEDURE...................................................................................................................................................5
ADJUSTMENT PROCEDURE AND SELF-CHECK ..................................................................................................................6
WAVEFORM PATTERN TABLE...............................................................................................................................................7
ALIGNMENT SETTINGS...........................................................................................................................................................8
BLOCK DIAGRAMS.................................................................................................................................................................. 9
PARTS LOCATION.................................................................................................................................................................13
REPLACEMENT PARTS LIST................................................................................................................................................ 14
SCHEMATIC DIAGRAMS.......................................................................................................................................................23
CONDUCTOR VIEWS.............................................................................................................................................................28
SAFETY PRECAUTIONS
GENERAL GUIDE LINES
1. It is advisable to insert an isolation transformer in the AC supply before servicing a hot chassis.
2. When servicing, observe the original lead dress in the high voltage circuits. If a short circuit is found, replace all parts that have been overheated or damaged by the short circuit.
3. After servicing, see that all the protective devices such as insulation barriers, insulation papers, shields and isolation R-C combinations are correctly installed.
4. When the receiver is not being used for a long period of time, unplug the power cord from the AC outlet.
5. Potentials as high as 29,5kV {29,2kV} [29kV] are 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 familiar with the precautions necessary when working on high voltage equipment. Always discharge the anode of the tube.
6. After servicing make the following leakage current checks to prevent the customer from being exposed to shock hazard.
LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper between the two prongs of the plug.
2. Turn on the receiver’s power switch.
3. Measure the resistance value with an ohmmeter, between the jumpered AC plug 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 4M ohm and 20M ohm. When the exposed metal does not have a return path to the chassis, the reading must be infinite.
LEAKAGE CURRENT HOT CHECK
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.
2. Connect a 2k 10W resistor in series with an exposed metallic part on the receiver and an earth, such as a water pipe.
3. Use an AC voltmeter with high impedance to measure the potential across the resistor.
4. Check each exposed metallic part and check the voltage at each point.
5. Reverse the AC plug at the outlet and repeat each of the above measurements.
6. The potential at any point should not exceed
1.4 Vrms. In case a measurement is outside the 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.
HOT CHECK CIRCUIT
A.C. VOLTMETER
2kΩ 10 Watts
TO INSTRUMENT’S EXPOSED METALLIC PARTS
Fig. 1.
X-RADIATION WARNING
1. The potential sources of X-Radiation in TV sets are the high voltage section and the picture tube.
2. When using a picture tube test jig for service, ensure that the jig is capable of handling 29,5kV without causing X-Radiation.
NOTE: It is important to use an accurate periodically calibrated high voltage meter.
1. Set the brightness to minimum.
2. Measure the high voltage. The meter should indicate. TX-28MD4 28,5kV ± 1kV. TX-25MD4 28,2kV ± 1kV. TX-21MD4 28kV ± 1kV. If the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.
3. To prevent any X-Radiation possibility, it is essential to use the specified tube.
WATER PIPE
(
EARTH)
2
SERVICE HINTS
How to remove the rear cover
1. Remove the 9 screws as shown in Fig.2.
LOCATION OF CONTROLS
SCREWS
Fig.2.
E-BOARD
H-BOARD
Fig.3.
FOCUS SCREEN
Y-BOARD
3
HOW TO MOVE THE CHASSIS INTO SERVICE POSITION
(A)
1. Remove the bead clamper from the mains lead and attach to the degauss coil, shown in Fig.5.
2. Hold and lift the rear of the E-PCB chassis and gently pull the chassis toward you, as shown in Fig.4.
3. Release the respective wiring clips and rotate the chassis horizontally through 90°, anti-cl ockwise.
4. Move the EHT lead around to the left side of the CRT neck.
5. Elevate the front of the chassis.
6. Clip the chassis frame onto the bead clamper, on the degauss coil, as shown in Fig.5.
7. Locate the base of the chassis frame into the hole (marked A), shown in Fig.6.
8. After servicing replace the bead clamper and ensure all wiring is returned to its original position before returning the receiver to the customer.
Fig.5.
Fig.4.
Fig.6.
4
ADJUSTMENT PROCEDURE
The remote control is used for entering and storing adjustments, with the exception of Cut-off adjustments, which must always be done prior to service adjustment. Perform adjustments in accordance with screen display. The display on the screen also specifies the software version as well as the approx. setting values. The adjustment sequence for the service mode is indicated below.
1. Set the Bass to maximum position, set the Treble to
minimum position, press the F button followed by the volume down button on the customer controls at the front of the TV and at the same time press the "INDEX" button on the remote control, this will place the TV into the Service Mode.
2. Press the RED / GREEN buttons to step up / down
through the functions.
NOTE: This TV also has the option of using a Memory Pack which enables you to copy the preset TV channels into the Memory Pack and then download them onto this or any other EURO-4 TV set.
3. Press the YELLOW / BLUE buttons to alter the function values.
4. Press the STR button after each adjustment has been made to store the required values.
5. To exit the Service Mode, press the "N" button.
TV to Memory Pack process
1. Plug the memory pack into the AV1 21 pin terminal at the back of the TV and switch the TV on.
2. Go into Service Mode as explained above. The screen will show :-
Program External>>TV
3. Press the BLUE button on the remote control. The screen will show :-
Program TV>>External
4. Press the STR button on the TV. The screen will show :-
Please Wait
5. All the tuning information stored inside the TV will now be transferred to the Memory Pack. This process will take 2-3 minutes to complete and when finished the screen will show :-
Complete
Memory Pack to TV process
1. Plug the memory pack into the AV1 21 pin terminal at the back of the TV and switch the TV on.
2. Go into Service Mode as explained above. The screen will show :-
Program External>>TV
3. Press the STR button on the TV. The screen will show :-
Please Wait
4. All the tuning information stored inside the Memory Pack will now be transferred to the TV. This process will take 2-3 minutes to complete and when finished the screen will show :-
Complete
5. The tuning information from the Memory Pack has now been copied into the TV.
6. To exit from the Service Mode press the "N" button.
7. The process has now been completed and the Memory Pack can now be removed.
ERRORS
If an error occurs while using the Memory Pack the TV will detect this and the screen will show :-
Error !!
Error !!
If this happens then press the "N" button and repeat the process that was being used. If the errors continue to occur then check the connectors between the TV and the memory pack and check the 9V battery inside the memory pack.
5
ADJUSTMENT PROCEDURE
Item / Preparation Adjustments +B SET-UP
1. Receive a Greyscale signal.
2. Set the controls :­Brightness Minimum Contrast Minimum Volume Minimum
CUT OFF / Ug2 Test
1. Receive a Greyscale signal.
2. Degauss the tube externally.
3. Set the TV into Service Mode 1.
4. Select Cut off mode.
1. Set the +B voltage up as follows:­Adjust R811 so that B2 shows 148V±1V [130V±1V
TX-21MD4]
2. Confirm the following voltages.
B9 5 ± 0,25V B10 5 ± 0,25V B5 12 ± 0,5V B11 33 ± 1,5V B4 16 ± 1V B7 8 ± 0,5V B12 26 ± 1V B8 5,5 ± 0,5V B3 35 ± 1V B13 15 ± 1V B1 200 ± 10V B14 -15 ± 1V
To adjust Cutoff connect an oscilloscope to the Blue cathode, adjust "cutoff" value using the "Yellow" and "Blue" buttons until the black level is 160V±5V press "STR" to store the value. Remove the oscilloscope. Select Ug2 adjustment and adjust the screen VR until the display shows "O.K."
SELF CHECK
Self-check is used to automatically check the bus lines and hexadecimal code of the TV set. To get into the Self-Check mode press the down (-/v) button on the customer controls at the front of the set, at the same time pressing the STATUS button on the remote control, and the screen will show :-
VDP O.K. TUN O.K. E2 O.K.
PCB O.K. Cab O.K. Sum
Factory use only
MSP O.K.
--
OPTION 1 3D [3C] OPTION 2 0C [0E] OPTION 3 1D [1D] OPTION 4 00 [00] OPTION 5 EF [EF] OPTION 6 23 [23]
If the CCU ports have been checked and found to be incorrect or not located then " - - " will appear in place of "O.K.".
Service Aids
To aid in the service of our current chassis there are a number of Service Aids which have been made available.
LUCI interface kit (Linked Utility Computer Interface) Part number: TZS6EZ002 This contains interface and cables for connecting TV service connector and a PC as well as diagnostic software. As new models are introduced upgrade software will become available.
VICI (Visual Interactive Computer Information) These C.D.'s contain multimedia documentation providing quick access to service information. Part No. TZS7EZ006 & TZS7EZ005
1. Service Manuals
2. Instruction Books
3. Technical Information
TASMIN (Technically Advanced System for Multimedia Interactive Notes) As well as providing a first step towards more interactive training this product also achieves quick access to Technical Information.
6
WAVEFORM PATTERN TABLE
Vert Out IC601 Pin 31
0.7V
H - Out IC601 Pin 50
3V
HFLB IC601 Pin 13
6.2V
20mS
64µS
Vert Drive IC451 Pin 2
57V
H - Out IC701 Pin 5
30mV
HFLB IC701 Pin 8
1.5V
20mS
64µS
VFLB IC451 Pin 3
1V
20mS
H - Pulse Base Q503
2V
64µS
Video Out IC601 Pin 59
2V
R - Out IC601 Pin 37
275mV
R - Out E8 Pin 5
4.6V
SCL IC1201 Pin 3
64µS
64µS
64µS
G - Out IC601 Pin 38
275mV
G - Out E8 Pin 3
4.4V
SVM Out IC601 Pin 34
64µS
64µS
64µS
64µS
B - Out IC601 Pin 39
275mV
64µS
B - Out E8 Pin 4
4.6V
64µS
3.7V 88mV
13µS
64µS
7
ALIGNMENT SETTINGS
(The figures below are nominal and used for representative purposes only.)
Alignment Function Settings / Special features
Horizontal Position
Vertical Position
Horizontal Amplitude
Vert. Amplitude
EW-amplitude
EW-amplitude
Trapezium-comp
Trapezium-comp
H-Pos
061
V-Pos
005
H-Amp
055
V-Amp
054
E/W-Amp1
-128
E/W-Amp2
006
Trapez-1
047
Trapez-2
-128
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Vertical Linearity
Vertical Symmetry
DVCO
Cut-off DC
Ug2 Test
Highlight
Lowlight
Sub-Brightness
V-Lin
006
V-Sym
002
DVCO
-005
Cut-off
0171
Ug2
055
O.K.
High 0902 0777 0864 Low 0117 0132 0112
Sub-Brightness
255
Optimum setting.
Optimum setting.
Receive a PAL Colour Bar Pattern. For DVCO alignment press "Blue" button, wait until the colours are changing slowly and press "STR". To adjust Cutoff connect an oscilloscope to the blue cathode, adjust "cutoff" value using the "Yellow" and "Blue" buttons until
the black level is 160V±5V press "STR" to store the value. Remove the oscilloscope. Select Ug2 adjustment and adjust the screen VR until the display shows "O.K."
Black Level
160V±5V GND
Optimum setting.
Optimum setting.
8
VIDEO BLOCK DIAGRAM
,Q
Q352Q35

,Q
&
Q35
9
AV1
9LGHR2XW
%OXH
*UHHQ
5HG
9LGHR
AV2
9LGHR
$9
E - BOARD




Q105
Q104
61 V IN 1
43 B IN 42 G IN 41 R IN
62 VIN 2
63 VIN 3
60 C IN
VIN 4
64
IC601
VIDEO
PROCESSOR
VIDEO OUT 59
Q3601
SVM OUT 34
B OUT 39
G OUT 38
R OUT 37
B IN 47
G IN 46
R IN 45
TX-28MD4 TX-25MD4
ONLY
Q950 Q951
Q303
Q304
Q301
Q302
E8
TX-28MD4 TX-25MD4
ONLY
Q905 Q907 Q909
7
7
4
4
IC351
3
Q908Q906
7
Q353
VM
COILS
Y - BOARD
RGB
4
OUTPUT
2
1
8
9
3
3
5
5
Y2
CRT
1
2XW
9LGHR
AV3
Q3001
68 CVBS
IC1101
MICRO
PROCESSOR
R 37
G 38 B 39
E15
6
8
1
E61
H - BOARD
H1
6
8
1
H3
Q3402
IC3401
8
VIDEO
SWITCHING
6
3
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