Before servicing this chassis, it is important that the service person read the "SAFETY PRECAUTIONS" and
"PRODUCT SAFETY NOTICE" contained in this manual.
This service manual provides service instructions for PTV Models WT-42313 and WT-42413 using the VK20 chassis.
Service personnel should read this manual thoroughly before servicing this chassis.
This service manual includes:
1. Assembly and disassembly instructions for the front and rear cabinet components.
2. Servicing of the Lenticular Screen and Fresnel Lens.
3. Servicing printed circuit boards (PCBs).
4. CRT replacement procedure.
5. Electrical adjustments.
6. Chip parts replacement procedures.
7. Circuit path diagrams.
The parts list section of this service manual includes:
1. Cabinet and screen parts.
2. Electrical parts.
Schematic and block diagrams of the above listed models are included in this service manual for better understanding of the circuitry. PCB drawings are also included for easy location of parts and test points.
PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in television receivers have special safety related characteristics. These
characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily be
obtained by using replacement components rated for higher voltage, wattage, etc.
Replacement parts which have special safety characteristics are identified in this service manual.
Electrical components having such features are identified by shading on the schematic diagram and by bold
type in the parts list of this service manual. The replacement for any safety part should be identical in value
and characteristics.
Page 5
MODEL: WT-42313 / WT-42413
SAFETY PRECAUTIONS
NOTICE:Observe all cautions and safety related notes located inside the receiver cabinet and on the
receiver chassis.
WARNING:
1.Operation of this receiver outside the cabinet or with the cover removed presents a shock hazard
from the receiver's power supplies. Work on the receiver should not be attempted by anyone who is
not thoroughly familiar with the precautions necessary when working on high voltage equipment.
2.Do not install, remove or handle the picture tubes in any manner unless shatterproof goggles are
worn. People not so equipped should be kept away while the picture tube is being handled. Keep
the picture tube away from the body while handling.
3.When service is required, observe the original lead dress. Extra precaution should be taken to
assure correct lead dress in the high voltage area. Where a short-circuit has occurred, replace those
components that indicate evidence of overheating.
X-Radiation warning
The surface of the cathode ray tubes (CRTs) may generate X-Radiation, so take proper precautions when servicing. It is recommended that a lead apron be used for shielding while handling the CRT. Use this method if
possible.
When replacing the CRTs, use only the designated replacement part since it is a critical component with regard to
X-Radiation. High voltage must be set as prescribed under the section titled Electrical Adjustments.
Leakage current check
Before returning the receiver to the customer, it is recommended that leakage current be measured according to
the following methods.
1. Cold Check
With the alternating current (AC) plug removed from the AC source, place a jumper across the two AC plug
prongs. Connect one lead of an ohm meter to the AC plug and touch the other lead to each exposed metal
part (i.e. antennas, handle bracket, metal cabinet, screw heads, metal overlay, control shafts, etc.), particularly any exposed metal part that has a return path to the chassis. The resistance of the exposed metal parts
having a return path to the chassis should be a minimum of 1Mega Ohm. Any resistance below this value
indicates an abnormal condition and requires corrective action.
2. Hot Check ...Use the circuit shown below to perform the hot check test.
1. Keep switch S1 open and connect the receiver to the measuring circuit. Immediately after
connection, and with the switching devices of the receiver in their operating positions, measure
the leakage current for both positions of switch S2.
2. Close switch S1, energizing the receiver. Immediately after closing switch S1, and with the
switching devices of the receiver in their operating positions, measure the leakage current for both
positions of switch S2. Repeat the current measurements of items 1 and 2 after the receiver has
reached thermal stabilization. The leakage current must not exceed 0.5 milliampere (mA).
Page 6
MODEL: WT-42313 / WT-42413
CABINET DISASSEMBLY (FRONT VIEW)
*Refer to PARTS LIST for Part Numbers
Front Cabinet Disassembly
1. Remove the Speaker Grille by pulling forward.
2. Remove the Board-Front by removing 3 screws "a".
3. Remove 3 screws “b” and then remove the Front Mask and Diamond Shield.
4. Remove 8 screws “c” and then the Assembly Screen.
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MODEL: WT-42313 / WT-42413
CABINET DISASSEMBLY (REAR VIEW)
Rear Cabinet Disassembly
1. Remove the Back Board by removing screws 7 "a".
2. Remove 6 screws "b" securing the Light Box Assembly.
3. Disconnect connector EJ.
4. Slide the Light Box Assembly out of the cabinet.
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MODEL: WT-42313 / WT-42413
SERVICING THE LENTICULAR SCREEN AND FRESNEL LENS
CAUTION:Wear gloves when handling the Lenticular Screen and Fresnel Lens.
This prevents cuts and finger prints. Do not place Fresnel Lens in the sun.
This may cause fire and heat related injuries.
1.Lenticular Screen and Fresnel Lens Removal
1. Remove the screen assembly as shown in the Cabinet Front Disassembly procedure.
2. Remove screws “a” from the bottom Corner Brackets.
3. Remove the Holder-Screen-Bottom.
4. Slide the Lenticular Screen and Fresnel Lens from the Assembly Screen as shown below..
Note: When separating the Lenticular Screen from the Fresnel Lens, use caution
while prying the Screen and Lens apart. Use a slot type screw drive, and
remove the pressure sensitive double sided tape.
2.Installation of the Lenticular Screen and Fresnel Lens
Note: Store the Lenticular Screen and Fresnel Lens in a cool dry place. High humidity may
deform the Lenticular Screen and Fresnel Lens.
1. Apply 36.5 inches of double sided tape (Part # LENS-TAPE) along the top front edge of the Fresnel Lens.
2. Place the Fresnel Lens on top of the Lenticular Screen and apply pressure at the top edge to
bond them together as shown below.
3. Reverse the disassembly procedure to install the screens in the screen frame.
Page 9
Accessing The Main Chassis
In the VK20 chassis, the Main Chassis is located in front of the CRTs. Use the following procedure to access
the Main Chassis.
1) Remove the Light Box Assembly, refer to the Cabinet Rear Disassembly.
2) The shelf in the front of the Light Box Assembly is removable, refer to Figure 1.
3) Release the shelf lock. Apply pressure to the shelf lip on the right side (downward and towards the
front). Refer to Figure 2
4) Hold both sides of the shelf, pull forward and then upward to remove the shelf.
MODEL: WT-42313 / WT-42413
SERVICING PCBs
Page 10
PCB Locations
MODEL: WT-42313 / WT-42413
Major Parts Locations
Page 11
CAUTION:To prevent damage, the following procedure must be used when removing an
Anode Lead from the Flyback Transformer.
1) Push the Anode Lead down.
1. Removal of the CRT
Caution!High voltage should be completely discharged prior to CRT removal.
Since the CRTs receive high voltage from the Flyback transformer, discharge the CRTs
by shorting the open end of the respective high voltage cable to chassis ground.
MODEL: WT-42313 / WT-42413
ANODE LEAD REMOVAL
2) While holding the lead down rotate
the lead 90º counter clockwise.
3) Carefully remove the Anode Lead
from the Flyback Transformer.
CRT REPLACEMENT
1. Refer to Cabinet Disassembly and remove the Light Box Assembly.
2. Remove the three Anode Lead Wires from the Flyback transformer and discharge the CRTs. (Use the
above procedure)
3. Unplug the three PCB-CRTs.
4. Remove 4 screws "a" retaining the Optical Unit. [Figure 1]
5. Remove 4 screws "b" retaining the Lens of the respective CRT
6. Lift the Optical Unit from the Light Box and set it lens down on a flat surface.
7. Remove 4 screws "c" retaining the CRT. [Figure 2]
Note: DO NOT loosen the spring loaded screws. Doing so will break the seal between the
C-Element and the # 6 Lens, causing leakage of the CRT Coolant.
8. Remove the Deflection Yoke from the neck of the CRT. [Figure 3]
Figure 1
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MODEL: WT-42313 / WT-42413
Figure 2
Note: The 4 spring-loaded screws shown
in Fig 2 and labeled as "DO NOT
REMOVE", should not be loosened
under any circumstance. Doing so
will break the seal between the
CRT and the CRT-Spacer, causing
leakage of the CRT Coolant.
2. Installation of the CRT
Note: The replacement CRT is supplied as an assembly comprised of the CRT and the
Inner Lens with the space between them filled with ethylene glycol. Care should
be taken during handling and installation to prevent shock from disrupting the seal
or alignment between the CRT and Inner Lens. [Figure 4]
Figure 3
Figure 4
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MODEL: WT-42313 / WT-42413
1. Carefully position the replacement CRT and fasten in place using 4 screws "c". [Figure 2]
2. Install the Deflection Yoke on the CRT neck. [Figure 3]
3. Install the Lens that was removed in step 5 of Removal of the CRT.
a) Position the Lens so that the Lens Adjustment Set Screw faces the rear of the TV [Figure 5].
b) Install the Lens mounting screws “b”. [Figure 1]
4. Insert the Optical Unit into the Light Box Assemblyand secure it with 4 screws “a” [Figure 1]..
5. Plug in the PCB-CRTs.
6. Insert the Anode Lead Wires into the Flyback Transformer.
7. Re-clamp the Lead Wire in its original position.
Adjustment procedures after replacing the CRT(s)
• CRT Cut Off / White Balance Adjustment
• Static Convergence Adjustment
• Dynamic Convergence Adjustment
Figure 5
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MODEL: WT-42313 / WT-42413
ELECTRICAL ADJUSTMENTS
Note: Perform only the adjustments required.
Do not attempt an alignment if proper equipment is not available.
1.Test Equipment
•Oscilloscope (Unless otherwise specified, use 10:1 probes)
•Signal Generator (both SD and HD capable)
•Frequency Counter
•Direct Current Voltmeter
Direct Current Power Supply
•Multiplex Audio Signal Generator
•Direct Current Ampere Meter
2.Test Signal
A. Monoscope Signal
Note: If you do not have
a monoscope signal source,
connect the unit to a VCR
and play a Monoscope
*alignment tape.
(* Part Number: 859C568060)
B. Color Bar Signal
Use the color bar signal shown
below, unless otherwise specified
in this manual.
Monoscope Signal
Split-Field Color Bars (100% window)
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MODEL: WT-42313 / WT-42413
AUDIO SETTINGS
VIDEO SETTINGS
TV Volume
PIP Source
PIP Position
POP Position
Format
PIP/POP Format
3.Initial Setup
A. Option Menu Setup
Follow the steps below for the initial set-up:
1. Select the "MENU" display by pressing the "MENU" button once.
2. Press the number buttons "0", "3", "7", "0" in sequence to select the "OPTION MENU" display.
3. Press the "ADJUST" button to select "INITIAL."
4. Press "ENTER."
NOTE: At this time channel 3 is automatically selected.
MENU-0-3-7-0
OPTION MENU
Initial
Power Restore:OFF
DTV Port:Auto
B. Default Settings
MAIN MENU DEFAULT SETTINGS
SETUP
Memorize channelsANT-A - AirFV- Fantasy ViolenceAllowBlueMax
Language (idioma)EnglishD-Sexual DialogAllow
Front Button LockOffL-Adult LanguageAllowA/V Memory ResetAnt-A
The “Power ON LED” provides an indication of the sets operation, and the possible cause of a malfunction.
A. Initial Control Circuitry Check
Immediately after the TV is connected to an AC power source:
• The LED flashes three times ... indicating the Microprocessor has initialized and is functioning
properly.
• If the LED does not flash ... the Microprocessor is NOT functioning.
B. Error Code Operational Check
Note: The TV must be in “Shut Down” and not heve been switched Off, to perform the Error Code Opera-
tional Check. When the TV is switched Off, the code automatically resets to “12” No Error.
Pressing the front panel “INPUT” and “MENU” buttons at the same time, and holding for 5 seconds,
activates the Error Code Mode. The LED flashes denoting a two digit Error Code, or indicating no problem
has occured since the last Initalization.
Note: The front panel buttons must be used, NOT those on the Remote Control.
• The number of flashes indicates the value of the MSD (tens digit) of the Error Code.
• The flashing then pauses for approximately 1/2 second.
• The LED then flashes indicating the value of the LSD (ones digit) of the Error Code.
• The Error Code is repeated a total of 5 times.
Example: If the Error Code is “23”, the LED will flash two times, pause, and then flash three
times.
C. Error Codes
The Error Code designations indicating a malfunction, or no malfunction, are listed below:
Error CodeDescription
12No error has occurred.
21X-Ray Protect circuit.
22Short Protect circuit.
23Deflection Loss
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MODEL: WT-42313 / WT-42413
5.Circuit Adjustment Mode
Except for the following, all adjustment items must be performed
using the remote hand unit.
• Lens Focus
• Electrostatic Focus
FUNCTIONCHASSIS
A. Activating the Circuit Adjustment Mode
1. Press the "MENU" button on a remote hand unit.
2. Press the number buttons "0", "3", "5", "7" in sequence.
The screen will change to the Adjustment Mode.
Note: Repeat steps 1 and 2 if the circuit
adjustment mode display does not appear
on screen
B. Selection of adjustment Functions and
Adjustment Items
To select an adjustment item in the circuit adjustment mode,
first select the adjustment function that includes the specific
adjustment item to be selected. Then, select the adjustment
item.
Refer to the following pages for the listing of adjustment
functions and adjustment items.
1. Press the "AUDIO" button on a remote hand unit to
select an adjustment function. Each time the button
is pressed, the Function changes in the following
sequence:
MODE
ITEM#
Video ChrK20
Mode 0NTSC
1SCT55
ABBREV.DATA
SIGNAL
Video ChrDefl Jung
FUNCTIONS
HRSub MatrxMain Mtrx
2. Press the “VIDEO” button to select a specific
Adjustment Item. The Item number increases each
time the “VIDEO” button is pressed.
C. Changing Data
After selecting an adjustment Item, use the “ADJUST
UP/DOWN” button to change data.
•Press “ADJUST DOWN” to decrease the data value.
•Press “ADJUST UP” to increase the data value.
MENU
ENTER
ADJUST
UP/DN
VIDEO
AUDIO
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MODEL: WT-42313 / WT-42413
SD
Coarse BLUE
1
HSTA
-50
D. Saving Adjustment Data
Press “ENTER” to save adjustment data in memory. The character display turns red for
approximately one second in this step.
Note: If the circuit adjustment mode is terminated without pressing “ENTER”, changes
in adjustment data are not saved.
E. Terminating the Circuit Adjustment Mode
Press the “MENU” button on the remote hand unit twice to terminate the adjustment mode.
Note: The circuit adjustment mode can also be terminated by turning power OFF.
F. Toggle Between Reception Modes
Pressing “3” when in the Adjustment Mode Video/Chroma Function toggles between 480i, 480p, and 1080i.
However data changes are not automatically saved. Press “ENTER” to save data before pressing “3”.
G. Service Mode Reset
To reset items in the service mode to their factory values:
1.Press MENU-0-3-5-7 to enter the Service Mode.
2.Press the “INPUT” or “DEVICE” button, on the front panel or the remote, and hold for 2 seconds
6.Convergence Adjustment Mode
The Convergence mode is used to perform raster geometry correction, and convergence adjustments as
specified in Adjustment Procedures 15 through 18.
A. Convergence Mode Activation
1.Press MENU-0-3-5-9
2.When the Convergence Mode is activated, the display at
the right appears on a Green Crosshatch.
Coarse Conv. Display
B. Selecting the HD or SD Mode
1.Select the Signal Source before entering the Convergence Mode, either an NTSC or HD source.
2.Enter the Convergence Mode (MENU-0-3-5-9)
• If the signal source is NTSC, the SD mode is activated.
• If the signal source is HD 1080i, the HD mode is activated.
3.Activating the HD mode when no HD signal is available.
• Activate the Factory Option Menu (MENU-0-3-7-0)
• Use the “Adjust” keys to select “DTV Port” and press “Enter” to change the setting to “1080i”.
Sequence = “Auto”-”480i”-480-p”-”1080i”. Ignore any loss of sync while changing modes.
• Exit the Option Menu (Press “MENU” twice).
• Select the DTV Inputs as the signal source (INPUT button).
• Activate the Convergence Mode ... the Convergence mode will be in the HD mode and the internal
crosshatch is displayed.
4.After adjusting Convergence, be sure to set the DTV Port back to AUTO.
• Select an analog input as the signal source (INPUT button).
• Activate the Option Menu (MENU-0-3-7-0).
• Use the “Adjust” keys to select “DTV Port and press “Enter” to change the setting from “1080i” to
“AUTO”.
• Exit the Option Menu (Press MENU twice).
C. Convergence Mode Functions
In the Convergence Mode there are three main Functions (Categories).
•Pressing “6” activates CONV MISC
•Pressing “5” activates COARSE CONV
•Pressing “4” activates FINE CONV
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