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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 under-
standing of the circuitry. PCB drawings are also included for easy location of parts and test points.

Note: For parts specific to the WT-42315,
refer to the attached addendum. For all other
service and parts information, refer to the
WT-42313 / WT-42413 Service Manual.

CONTENTS Page
Schematic Diagrams
Overall PCB Block Diagram ...................................................... 1
PCB-POWER ........................................................................... 2
PCB-MAIN ................................................................................ 3
PCB-TERMINAL-1 (A/V Switch & Decoders) ............................ 4
PCB-TERMINAL-2 (3DYC) ....................................................... 5
PCBs - CRTs / PRE-AMP /CONTROL / SVM / DBF ................. 6
PCB-SIGNAL-1 (AV I/O)............................................................ 7
PCB-SIGNAL-2 (MICRO) .......................................................... 8
PCB-SIGNAL-3 (Video/Chroma ................................................ 9
PCB-SIGNAL-4 (Convergence Generator) .............................. 10
PCB-UNI ................................................................................. 11
PCB-DOUBLER-1 (Input) ........................................................ 12
PCB-DOUBLER-2 (Main) ....................................................... 13
PCB-DOUBLER-3 (Output) ..................................................... 14