2002
Service
MITSUBISHIELECTRIC Manual
PROJECTION TELEVISION V20B CHASSIS
V20B
MODELS
WS-A48
VS-A50
WS-A55
WS-A65
CAUTION:
Before servicing this chassis, it is important that the service person read the "SAFETY PRECAUTIONS" and "PRODUCT SAFETY NOTICE" contained in this manual.
SPECIFICATIONS
• Power |
: AC 120V, 60Hz |
• Speaker |
: [VS-A50] |
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Two 4" round, full range (8Ω 5W) |
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240W |
(Except WS-73411) |
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275W |
(WS-73411 Only) |
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: [WS-A48 / WS-A55 / WS-A65] |
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Two 5" round, full range (8Ω 10W) |
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• Frequency |
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: VHF |
54 ~ 470MHz |
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Range |
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UHF |
470 ~ 806MHz |
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• Antenna Input |
: VHF/UHF 75Ω unbalanced |
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• CRT Size |
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: 7 inches |
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• High Voltage |
: 32.0kV (at 0A) |
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• Weight / Cabinet Demensions |
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Model |
Weight |
Height |
Width |
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Depth |
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VS-A50 |
200 lbs |
50.3" |
42.4" |
|
23.6" |
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WS-A48 |
171.5 lbs |
|
49" |
44.5" |
|
23" |
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WS-A55 |
237 lbs |
|
50" |
50.6" |
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26.3" |
|
WS-A65 |
326.5 lbs |
61.9" |
59" |
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28.1" |
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•Weight and dimensions shown are approximate.
•Design specifications are subject to change without notice.
• Input Level : VIDEO IN JACK (RCA Type) 1.0Vp-p 75Ω unbalanced
:AUDIO IN JACK (RCA Type) -4.7dBm 43kΩ unbalanced
:S-VIDEO IN JACK (Y/C separate)
Y=1.0 Vp-p C=0.286Vp-p(BURST) 75Ω unbalanced
:COMP / Y, Cr, Cb (RCA Type) Y=1.0 Vp-p. Cr, Cb=700mVp-p
:ATV / Y(G), Pr(R), Pb(B), H, V
Y 1.0Vp-p with sync 75Ω (RCA Type) Pr, Pb: 700mV 75Ω
H, V: 3.0Vp-p 75Ω
•Output Level : VIDEO OUT JACK (RCA Type)
1.0Vp-p 75Ω unbalanced
:AUDIO OUT JACK (RCA Type) -4.7dBm 4.7kΩ unbalanced
MITSUBISHI DIGITAL ELECTRONICS AMERICA, INC.
9351 Jeronimo Road, Irvine, CA 92618-1904
Copyright © 2002 Mitsubishi Digital Electronics America, Inc.
All Rights Reserved
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CONTENTS |
|
INTRODUCTION ................................................................................................................................ |
5 |
PRODUCT SAFETY NOTICE ............................................................................................................. |
5 |
SAFETY PRECAUTIONS ................................................................................................................... |
6 |
CABINET DISASSEMBLY |
|
WS-A48 (Front View) ............................................................................................................. |
7 |
WS-A48 (Rear View) .............................................................................................................. |
8 |
VS-A50 / WS-A55 / WS-A65 (Front View) ............................................................................. |
9 |
VS-A50 / WS-A55 / WS-A65 (Rear View) ............................................................................ |
10 |
SERVICING THE LENTICULAR SCREEN AND FRESNEL LENS |
|
Lenticular Screen and Fresnel Lens Removal ......................................................................... |
11 |
VS-A50 / WS-A55 / WS-A65 ............................................................................................... |
11 |
WS-A48 ............................................................................................................................... |
12 |
Lenticular Screen and Fresnel Lens Installation .................................................................... |
13 |
CABINET SEPARATION |
|
WS-A65 ............................................................................................................................... |
14 |
SERVICING THE DIAMONDSHIELDTM |
|
DiamondShieldTM Removal & Installation ....................................................................................... |
15 |
SERVICING PCBs |
|
Chassis Removal .......................................................................................................................... |
16 |
PCB Locations .............................................................................................................................. |
16 |
Main Components Location........................................................................................................... |
16 |
Second Anode Lead Removal........................................................................................................ |
17 |
CRT REPLACEMENT |
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CRT Removal ................................................................................................................................ |
17 |
CRT Installation ............................................................................................................................ |
18 |
ELECTRICAL ADJUSTMENTS |
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Test Equipment ............................................................................................................................. |
20 |
Initial Setup ................................................................................................................................... |
21 |
LED Indicator Diagnostics ............................................................................................................. |
22 |
Circuit Adjustment Mode ............................................................................................................... |
23 |
Convergence Adjustment Mode ..................................................................................................... |
24 |
Adjustment Items List ................................................................................................................... |
26 |
Adjustment Test Points ................................................................................................................. |
29 |
Adjustment Procedures |
|
High Voltage Regulation ....................................................................................................... |
30 |
Main/Sub Y Level ................................................................................................................. |
30 |
Main/Sub Color Level ........................................................................................................... |
31 |
CRT Cutoff ........................................................................................................................... |
31 |
White Balance (NTSC) ......................................................................................................... |
32 |
White Balance (HD) ............................................................................................................. |
32 |
Black Level .......................................................................................................................... |
33 |
Sub Contrast ....................................................................................................................... |
33 |
Dynamic Focus Preset ........................................................................................................ |
34 |
Lens Focus .......................................................................................................................... |
34 |
Electrostatic Focus & Alignment Magnet Adjustment ........................................................... |
35 |
Page 3
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
On Screen Display Character Position ................................................................................. |
35 |
Deflection/Convergence Geometry Presets .......................................................................... |
36 |
Deflection Circuit Geometry Adjustments ............................................................................. |
37 |
Convergence Circuit Geometry Adjustments ........................................................................ |
38 |
Centering and Static Convergence ........................................................................................ |
39 |
Coarse Convergence Adjustments ........................................................................................ |
40 |
Fine Convergence Adjustments ............................................................................................ |
41 |
CHIP PARTS REPLACEMENT ......................................................................................................... |
42 |
REPLACEMENT PARTS |
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Parts Ordering .............................................................................................................................. |
43 |
Critical and Warranty Parts Designation........................................................................................ |
43 |
Parts Tolerance Codes .................................................................................................................. |
43 |
Replacement Part Notes |
|
When replacing the RF-Switch or PCB-SIGNAL ................................................................... |
43 |
When replacing the EEPROM.............................................................................................. |
43 |
Quick Reference List .................................................................................................................... |
44 |
Service Parts List.......................................................................................................................... |
45 |
Screen Parts List .......................................................................................................................... |
56 |
CIRCUITRY BLOCK DIAGRAMS |
|
Power Supply ............................................................................................................................... |
58 |
Video / Color Signal Path .............................................................................................................. |
59 |
Sync Signal Path .......................................................................................................................... |
60 |
Deflection / HV .............................................................................................................................. |
61 |
X-Ray Protect ............................................................................................................................... |
62 |
HV Regulation ............................................................................................................................... |
63 |
Sound Signal Path ........................................................................................................................ |
64 |
Convergence ................................................................................................................................. |
65 |
Control Circuitry ............................................................................................................................ |
66 |
Section 2 .... Schematic Diagrams |
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SCHEMATIC DIAGRAMS |
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Overall Block Diagram ................................................................................................................... |
1 |
PCB-MAIN ..................................................................................................................................... |
2 |
PCB-POWER................................................................................................................................. |
3 |
PCB-TERMINAL (Input Sw) ............................................................................................................. |
4 |
PCB-TERMINAL (3DYC / Decoders) ............................................................................................... |
5 |
PCB-SIGNAL-1 (AV I.O) .................................................................................................................. |
6 |
PCB-SIGNAL-2 (Micro) ................................................................................................................... |
7 |
PCB-SIGNAL-3 (VCJ) ..................................................................................................................... |
8 |
PCB-SIGNAL-4 (Convergence Generator) ........................................................................................ |
9 |
PCBs - FRONT / CONTROL / CRT / PREAMP ............................................................................. |
10 |
PCB-2HDW-1 (Input) ..................................................................................................................... |
11 |
PCB-2HDW-2) (Main) .................................................................................................................... |
12 |
PCB-2HDW-3 (Output) .................................................................................................................. |
13 |
PCB LAYOUT DIAGRAMS ............................................................................................................... |
14 |
Page 4
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
INTRODUCTION
This service manual provides service instructions for the PTV Models listed below. Service personnel should read this manual thoroughly before servicing these chassis.
V20B CHASSIS
VS-A50
WS-A48
WS-A55
WS-A65
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
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
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
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CABINET DISASSEMBLY (FRONT VIEW)
WS-A48
*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 screws "a".
3.Remove the Screen Assembly by removing screws "b". Disconnect all cable harnesses between the Screen Assembly and the PCB-Signal.
4.Lift the Screen Assembly and pull up and away from the cabinet as shown.
Page 7
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CABINET DISASSEMBLY (REAR VIEW)
WS-A48
Rear Cabinet Disassembly
1.Remove the Back Board by removing screws "a", “b” and “c”.
2.Remove the Back Cover by removing screws "e".
3.Remove 4 screws "d" securing the Light Box Assembly.
4.Be certain that all cables and connectors between the Light Box Assembly and external items are disconnected (e.g. speaker plugs).
5.Slide the Light Box Assembly out of the cabinet.
Page 8
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CABINET DISASSEMBLY (FRONT VIEW)
VS-A50 WS-A55
WS-A65
Front Cabinet Disassembly
1.Remove the Speaker Grille by pulling forward.
2.Remove the Front-Board by removing screws "a".
3.Remove the Screen Assembly by removing screws "b". Disconnect all cable harnesses between the Screen Assembly and the PCB-Signal.
4.Lift the Screen Assembly and pull up and away from the cabinet as shown.
Page 9
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CABINET DISASSEMBLY (REAR VIEW)
VS-A50 WS-A55
WS-A65
Rear Cabinet Disassembly
1.Remove the Back Board by removing screws "a".
2.Remove the Board Slide by removing screws “b”.
3.Remove the two Board Shelves by removing screws “c”.
4.Remove 4 screws "d" securing the Light Box Assembly.
5.Be certain that all cables and connectors between the Light Box Assembly and external items are disconnected (e.g. speaker plugs).
6.Slide the Light Box Assembly out of the cabinet.
Page 10
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
SERVICING THE LENTICULAR SCREEN AND FRESNEL LENS
VS-A50 WS-A55
WS-A65
1. Removal of the Lenticular Screen and Fresnel Lens
CAUTION: Wear gloves when handling the Lenticular Screen and the Fresnel Lens.
This prevents cuts and finger prints. Do not place the Fresnel Lens in the sun. This may cause fire and heat related injuries.
1.Remove the screen assembly as shown in the Cabinet Disassembly procedure.
2.Remove the Screen Holder by removing screws (a).
3.Slide the Lenticular Screen and Fresnel Lens from the Screen Frame.
Note: When separating the Lenticular Screen from the Fresnel Lens, use caution while prying the Screen and Lens apart. Use a slot type screw driver, and remove the pressure sensitive, double sided tape.
Page 11
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
SERVICING THE LENTICULAR SCREEN AND FRESNEL LENS
WS-A48
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.
1c. Lenticular Screen and Fresnel Lens Removal
1.Remove the screen assembly as shown in the Cabinet Disassembly procedure.
2.Remove the Top, Bottom and Side Holder Screens..
3.Carefully lift the Lenticular Screen and Fresnel Lens combination from the Screen Frame Assembly.
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.
Page 12
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
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 double coated tape (Part # LENS-TAPE) along the top front edge of the Fresnel Lens as shown in Figure 2-2. Refer to Table A and Table B for proper tape length.
2.Place the Fresnel Lens on top of the Lenticular Screen and apply pressure at the top edge to bond them together as shown in Figure 2-2.
3.Reverse the disassembly procedure for that model to install the screens in the screen frame.
Fresnel Lens
Top
( * X ) inch
Top
Double Sided Tape
(Part# LENS-TAPE)
Bottom
Bottom
Lenticular Screen
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Figure 2-2 |
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4:3 Aspe ct Mode ls |
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Mode l |
Scre e n |
Ta pe |
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Size |
Le ngth |
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VS-A50 |
50" |
40" |
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Table A |
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16:9 Aspe ct Mode ls |
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Mode l |
Scre e n |
Ta pe |
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Size |
Le ngth |
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W S-A48 |
48" |
41.76 |
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W S-A55 |
55" |
47.85 |
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W S-A65 |
65" |
56.55 |
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Table B |
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Fresnel Lenticular
Lens Screen
0.16 inch
Page 13
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
CABINET SEPARATION PROCEDURE
(WS-A65)
Model WS-A65 cabinet is assembled in two pieces. These two pieces may be separated to allow easier delivery and setup.
Cabinet Separation Precedure
1.Remove the Screen Assembly and disconnect all cable harnesses between the Frame Assembly and the PCB-SIGNAL, refer to Cabinet Front Disassembly.
2.Remove the 4 screw covers “a”.
3.Remove 4 screws “b” securing the top and bottom cabinet sections .
4.Carefully lift the cabinet top and place it on the floor.
5.Place the cabinet bottom in the desired location.
6.Reverse the procedure and mount the cabinet top on the cabinet bottom.
7.Reinstall the the Screen Assembly and connect all cable harnesses between the Screen Assembly and the PCB-SIGNAL.
Page 14
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
SERVICING THE DIAMONDSHIELD™
1. DiamondShield™ Removal Procedure
The location of the DiamondShieldTM molding clips may vary between models, top and bottom, or sides. Use the appropriate disassembly procedure given below.
Note: Wear gloves when handling the DiamondShield™ to prevent finger prints.
Top & Bottom Molding Clips |
Side Molding Clips |
1.Gently insert a small screwdriver between the DiamondShield™ and one end of the clip to pry the clip loose.
2. Remove both clips by pulling them toward you.
3.Carefully insert a small screwdriver into the gap at the top/center point of the Shield and pull the Shield slightly away from the unit. Place your hands at the points shown and gently bow the Shield toward you and remove from the unit. Then re-install the two clips.
1.Gently insert a small screwdriver between the DiamondShield™ and one end of the clip to pry the clip loose.
2. Remove both clips by pulling them toward you.
3.Carefully insert a small screwdriver into the gap at the side/center point of the Shield and pull the Shield slightly away from the unit. Place your hands at the points shown and gently bow the Shield toward you and remove from the unit. Then re-install the two clips.
2. DiamondShield™ Installation Procedure
*(See the Parts List for DiamondShield™ part numbers)
To install the DiamondShieldTM, reverse the above Removal Procedure.
Page 15
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
SERVICING PCBs
Chassis Removal and PCB Locations
Chassis Removal
1)Remove screw “a” from the Main Chassis.
2)Raise the two chassis locks on the inner sides of the Lightbox Assembly and slide the chassis towards the rear.
Major Parts Locations
Page 16
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
ANODE LEAD REMOVAL
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.
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. 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 by shorting the open end of the respective high voltage cable to chassis ground.
Note: Refer to Cabinet Disassembly when performing steps 1 through 4.
1.Remove the Speaker Grille, Front Board, and Screen Assy.
2.Remove the Back Board.
3.Remove the Anode Lead Wire from the Flyback transformer. (Use the above procedure)
4.Remove the PCB-CRT.
5.Remove 4 hex-screws "a" retaining the Optical Unit. [Figure 5-1]
6.Remove 4 screws "b" retaining the Lens.
Note: DO NOT loosen the RED screws. Doing so will break the seal between the C-Element and the # 6 Lens, causing leakage of the CRT Coolant.
7.Remove 4 screws "c" retaining the CRT. [Figure 5-2]
8.Remove the Deflection Yoke from the neck of the CRT. [Figure 5-7]
Figure 5-1
Page 17
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
Note: The 4 spring-loaded screws shown in Fig 5-2 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.
Figure 5-2
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 5-3]
Figure 5-3
Figure 5-5
Figure 5-4
Page 18
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
1.Carefully position the replacement CRT and fasten in place using 4 screws "d". [Figure 5-5]
2.Install the Deflection Yoke on the CRT neck. [Figure 5-6]
3.Install the Lens that was removed in steps 5 and 6 of Removal Of The CRT. [ Figures 5-1 and 5-2 ]
a)Position the Lens so that the Label faces the direction shown in Figure 5-7
b)Install the mounting screws. [Figure 5-1]
4.Install the PCB-CRT.
5.Insert the Optical Unit into the Light Box Assembly.
6.Insert the Anode Lead Wire into the Flyback Transformer.
7.Re-clamp the Lead Wire in its original position.
Figure 5-6
Figure 5-7
Adjustment procedures after replacing the CRT(s)
•CRT Cut Off / White Balance Adjustment
•Static Convergence Adjustment
•Dynamic Convergence Adjustment
Page 19
MODELS: VS-A50 / WS-A48 / WS-A55 / WS-A65
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
100%
75%
40%
40%
1H
Split-Field Color Bars (100% window)
Page 20
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