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Technical Guide
Colour Television
GP 31 Chassis
Circuit Explanations
Panasonic Panasonic AVC Networks
Kuala Lumpur Malaysia Sdn. Bhd.
1
Contents
Introduction 3
Location of Control & Circuit Boards 4
GP-31 Chassis Block Diagram 5
1. Tuning Circuit
1.1 Signal Processing 6
1.2 IF Control 6
2. Ultimate One Chip IC601
2.1 Features 8
2.2 IIC Bus 9
2.3 Memory IC 9
2.4 Reset Circuit 10
2.5 IC601 Pin Configuration 11
3. Video Circuit
3.1 Video Signal Processing 14
4. Audio Circuit
4.1 Audio Processor 17
4.1.1 Sound Processor 17
4.1.2 Audio Amplifier 17
5. Deflection Circuit
5.1 Horizontal Output Circuit 20
5.1.1 Horizontal Output Operation 21
5.2 Vertical Output Circuit 23
5.2.1 Vertical Output Operation 23
6. Colour Output
6.1 Colour Output Stage 24
7. Protection Circuit 25
8. Power Circuit
8.1 Start-up Circuit 29
8.2 Output Voltage Control 29
8.3 Regulation 30
8.4 Over Voltage Protection Circuit 30
8.5 Over Current Protection Circuit 31
8.6 Latch Circuit 31
8.7 Standby Operation 31
2
! WARNING
This service information is designed for experienced repair technicians only and is not
designed for use by general public. It does not contain warnings or cautions to advise
non-technical individuals of potential dangers in attempting to service a product. Products
powered by electricity should be serviced or repaired only by experienced professional
technicians. Any attempt to service or repair the product or products dealt with in this
service information by anyone else could result in serious injury or death.
Introduction
We at Panasonic realise that the service engineer needs to understand the circuitry
inside the TV and for this need, we have produced this Technical Guide.
This Technical Guide contains information for GP 31 chassis and should be used
in conjunction with the relevant Service Manuals for this chassis.
As the Technical Guide for the GP 31 chassis covers such a wide range of models,
some differences may occur in circuit descriptions and component references.
3
Location of Control & Circuit Boards
L-Board
A- Board
Board Name Function
A-Board Main Board
L-Board CRT Board
4
GP-31 Chassis Block Diagram
5
1. Tuning Circuit
Outline
Fig 1.0
The tuner is designed for reception of the conventional frequencies to date and the
intermediate special channel frequencies. The IF stage of the tuner contains the video and
audio demodulators which are designed for most widely used TV standards.
1.1 Signal Processing
1. The purpose of the tuner is to convert the VHF/ UHF TV broadcast signal (RF) into
intermediate frequency signal, IF (38.0MHz) [Fig 1.0].
2. The aerial intercepts the TV signal and amplified by the RF amplifier.
3. The local oscillator generates basic frequency to convert RF signal into IF signal
(intermediate signal) in the mixer.
4. Here the IF signals is output to UOC IC601 for video and sound processing.
1.2 IF Control
Control of internal Tuner-IF processing is performed by the UOC IC601, the
IC601 sending control information via I