Panasonic TX-25MDT4F, TX-28MDT4F Schematic
TX-28/25MDT4F Service Manual
Safety
Specifications
Parts List
Service
Information
Adjustments
Self Check
Service Hints
Mechanical
View
Disassembly
Location of
Controls
Waveforms
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
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Control |
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Power supply |
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Video |
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BACK
E - Schematic H - Schematic
E - PCB |
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Y - PCB |
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Y - Schematic
BACK
BACK
SPECIFICATIONS
(Information in brackets { } refers to model TX-25MDT4F)
Power Source: |
220-240V AC, 50Hz |
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Power Consumption: |
85W |
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Aerial Impedance: |
75Ω unbalanced, Coaxial Type |
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Stand-by Power |
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Consumption: |
1,8W |
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Receiving System: |
PAL B, G, H, I D/K, PAL-525/60 |
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SECAM B/G, D/K, L/L’ |
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M.NTSC |
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NTSC (AV only) |
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Receiving Channels: |
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VHF E2-E12 |
VHF H1-H2 (ITALY) |
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VHF A-H (ITALY) |
VHF R1-R2 |
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VHF R3-R5 |
VHF R6-R12 |
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UHF E21-E69 |
CATV (S01-S05) |
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CATV S1-S10 (M1-M10) |
CATV S11-S20 (U1-U10) |
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CATV S21-S41 (HYPERBAND) |
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Intermediate Frequency |
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Video |
38,9MHz 34MHz |
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Audio |
32,9MHz, 33,4MHz, 33,16MHz |
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32,4MHz, 40,4MHz, 33,05MHz |
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32,66MHz |
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Colour |
34,47MHz (PAL) |
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34,5MHz, 34,65MHz (SECAM) |
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Terminals: |
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500mV rms 1kΩ |
AUDIO MONITOR OUT |
Audio (RCAx2) |
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AV1 IN |
Video (21 pin) |
1V p-p 75Ω |
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Audio (21 pin) |
500mV rms 10kΩ |
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RGB (21 pin) |
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AV1 OUT |
Video (21 pin) |
1V p-p 75Ω |
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Audio (21 pin) |
500mV rms 1kΩ |
ORDER No. SM-98035
Colour Television
TX-28MDT4F
TX-25MDT4F
EURO4 Chassis
AV2 IN |
Video (21 pin) |
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1V p-p 75Ω |
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Audio (21 pin) |
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500mV rms 10kΩ |
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S-Video IN |
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Y: 1V p-p 75Ω |
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(21-pin) |
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C:0.3V p-p 75Ω |
AV2 OUT |
Video (21 pin) |
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1Vp-p 75Ω |
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Audio (21 pin) |
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500mV rms 1kΩ |
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Selectable output (21 pin) |
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AV3 IN |
Audio (RCAx2) |
500mV rms 10kΩ |
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Video (RCAx1) |
1V p-p 75Ω |
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High Voltage: |
28,5kV ±1kV |
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{28,2kV ±1kV} |
Picture Tube: |
A66ECF50X41 |
66cm |
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Audio Output: |
{A59ECF50X41 |
59cm} |
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2 x 15W (Music Power) |
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8Ω Impedance |
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Headphones: |
8Ω Impedance |
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Accessories |
3,5 mm |
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supplied : |
Remote Control |
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2 x R6 (UM3) Batteries |
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Dimensions: |
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Height: |
580 mm |
{531 mm} |
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Width: |
666 mm |
{601 mm} |
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Depth: |
472 mm |
{439 mm} |
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Net weight: |
31kg |
{25kg} |
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Specifications are subject to change without notice. Weights and dimensions shown are approximate.
NOTE: This Service Manual should be used in conjunction with the EURO4 Technical guide.
CONTENTS |
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SAFETY PRECAUTIONS.......................................................................................................................................................... |
2 |
SERVICE HINTS ....................................................................................................................................................................... |
3 |
ADJUSTMENT PROCEDURE................................................................................................................................................... |
4 |
ADJUSTMENT PROCEDURE AND SELF-CHECK .................................................................................................................. |
5 |
WAVEFORM PATTERN TABLE ............................................................................................................................................... |
6 |
ALIGNMENT SETTINGS........................................................................................................................................................... |
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BLOCK DIAGRAMS .................................................................................................................................................................. |
8 |
PARTS LOCATION ................................................................................................................................................................. |
12 |
REPLACEMENT PARTS LIST ................................................................................................................................................ |
13 |
SCHEMATIC DIAGRAMS ....................................................................................................................................................... |
22 |
CONDUCTOR VIEWS............................................................................................................................................................. |
26 |
SAFETY PRECAUTIONS |
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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} 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 2kΩ 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
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WATER PIPE |
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2kΩ 10 Watts |
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(EARTH) |
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-28MDT4F |
28,5kV |
± |
1kV. |
TX-25MDT4F |
28,2kV |
± |
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.
2
SERVICE HINTS
How to remove the rear cover
1.Remove the 9 screws as shown in Fig.2.
SCREWS
Fig.2.
LOCATION OF CONTROLS
FOCUS
SCREEN
E-BOARD |
H-BOARD |
Y-BOARD
Fig.3.
3
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.
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.
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.
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 !!
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.
4
ADJUSTMENT PROCEDURE
Item / Preparation
+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.
Adjustments
1.Set the +B voltage up as follows:- Adjust R811 so that B2 shows 148V±1V.
2.Confirm the following voltages.
B9 |
5 |
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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 |
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B3 |
35 |
± |
1V |
B13 |
15 |
± |
1V |
B1 |
200 ± |
10V |
B14 |
-15 ± |
1V |
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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. |
PCB |
O.K. |
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TUN |
O.K. |
Cab |
O.K. |
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E2 |
O.K. |
Sum |
Factory use only |
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MSP |
O.K. |
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DPL |
- - |
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OPTION1 |
3D |
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OPTION2 |
0C |
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OPTION3 |
1D |
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OPTION4 |
00 |
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OPTION5 |
EF |
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OPTION6 |
23 |
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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.
5
WAVEFORM PATTERN TABLE
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Vert Out |
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Vert Drive |
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VFLB |
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IC601 Pin 31 |
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IC451 Pin 2 |
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IC451 Pin 3 |
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0.7V |
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57V |
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1V |
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20mS |
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20mS |
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20mS |
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H - Out |
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H - Out |
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H - Pulse |
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IC601 Pin 50 |
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IC701 Pin 5 |
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Base Q503 |
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3V |
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30mV |
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2V |
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64 S |
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64 S |
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64 S |
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HFLB |
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HFLB |
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Video Out |
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IC601 Pin 13 |
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IC701 Pin 8 |
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IC601 Pin 59 |
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6.2V |
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1.5V |
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2V |
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64 S |
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R - Out |
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G - Out |
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B - Out |
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IC601 Pin 37 |
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IC601 Pin 38 |
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IC601 Pin 39 |
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275mV |
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275mV |
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275mV |
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64 S |
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64 S |
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64 S |
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R - Out |
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G - Out |
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B - Out |
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E8 Pin 5 |
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E8 Pin 3 |
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E8 Pin 4 |
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4.6V |
4.4V |
4.6V |
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64 S |
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64 S |
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64 S |
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SCL |
SVM Out |
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IC1201 Pin 3 |
IC601 Pin 34 |
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3.7V |
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88mV |
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13 S |
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64 S |
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6
ALIGNMENT SETTINGS
(The figures below are nominal and used for representative purposes only.)
Alignment Function
Horizontal Position
H-Pos
061
Vertical Position
V-Pos
005
Horizontal Amplitude
H-Amp
055
Vert. Amplitude
V-Amp
054
EW-amplitude
E/W-Amp1
-128
EW-amplitude
E/W-Amp2
006
Trapezium-comp
Trapez-1
047
Trapezium-comp
Trapez-2
-128
Vertical Linearity
V-Lin
006
Vertical Symmetry
V-Sym
002
DVCO
DVCO -005
Cut-off DC
Cut-off
0171
Ug2
Ug2 Test 055
O.K.
Settings / Special features
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
Optimum setting.
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
Highlight |
High |
0902 |
0777 |
0864 |
Optimum setting. |
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Lowlight |
Low |
0117 |
0132 |
0112 |
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Sub-Brightness |
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Sub-Brightness |
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Optimum setting. |
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255 |
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7
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