FROM CRYSTAL SETS TO 405 LINE TELEVISION

Introduction

In recent years there has been an increased interest in the old wireless and television receivers that were prevalent in the 1930s, 40s and 50s. Many people now collect such sets. Unfortunately mainstream electronics servicing organisations often seem very reluctant to take on the repair of them. There are specialists companies that undertake such work, but inevitably a fairly heavy fee is charged that maybe beyond the pocket of some collectors.

It seems a shame that failed radios and televisions should merely remain ornaments. What is required is a way of teaching the collector some basic electronics knowledge. This book tries to do just that, it is aimed primarily at the non-technical collector and hopefully will help them to understand how their sets work and encourage them to "have a go" at mending faulty sets within their collection. The book assumes no former knowledge of electronics, either of the valve era or of modern micro-electronics. It is necessary to cover a certain amount of basic theory but this has been kept to a minimum and is non-mathematical in nature. If chapter 1 is skipped, the book will also be of interest to the younger electronics technician who has limited knowledge of valves. The text relies heavily on diagrams throughout and wherever possible gives the circuit diagram of a practical application of the topic under discussion.

The book covers the early days of radio up to the introduction of the 405-line television system, broadly up to 1955. I have therefore not included the PAL colour system, F.M radio, or solid-state electronics beyond a reference to germanium diodes, which were beginning to find their way into domestic electronics by the 1950s. I discriminate against the later technology only because I need to limit the scope of the text somehow. Personally I find some of the later technology fascinating, especially the first colour televisions; in particular the “hybrid” sets with their rich mixture of valve and transistor circuitry.

The book is designed in a 3 part format. Part A takes the reader through basic electronics theory, and then applies the theory to practical radio circuits. Part B of the book deals with repairing old valve radio receivers, including a section covering safety considerations. Part C deals with 405-line television receivers; first the theory of operation is covered, then practical applications. Part C ends with a section of faultfinding. Repetition between the radio and television faultfinding sections has been kept to a minimum; the television section assumes that the radio faultfinding section has been read first.

The book does not deal with non-technical topics such as case repairs and how to find sets to restore. Several texts cover such information; I would recommend in particular Electronic Classics by Andrew Emmerson.

Although much of this book is applicable to foreign readers, the text is written assuming a British readership. Therefore please take account of the fact that mains voltage is assumed to be 230V volts as used in the British domestic environment. The following terms differ between British and American English: -

American       British

Plate              Anode
Ground          Earth
B+                  HT
Line                Mains
Tube               Valve
Rosin              Resin

Any (constructive) suggestions on how the book can be improved will be gratefully received by the author.

THE LEGAL STUFF

PLEASE NOTE

Every care has been taken in writing this book but with the best will in the world errors and omissions do occur. The author can take no responsibility for damage or injury to persons or property resulting from any information contained in this book.

This publication has NOT been released into the public domain. It remains the exclusive property of the author and is placed here as public service. Please do not reproduce any part of the publication without the express permission of the author.

Copyright (c) 2002- 2010 Chris Garnett

Introduction
Contents
Chapter 1:BASIC COMPONENTS
Chapter 2:INTRODUCTION TO THE VALVE
Chapter 3:THE USE OF VALVES
Chapter 4:HOW A RADIO RECEIVER WORKS
Chapter 5:POWER SUPPLIES
Chapter 6:SAFETY
Chapter 7:TOOLS AND SKILLS
Chapter 8:DEALING WITH A “DEAD” RADIO
Chapter 9:PARTIALLY WORKING SETS
Chapter 10:SETTING UP RADIOS
Chapter 11:405 LINE TELEVISIONS: INTRODUCTION AND PRINCIPLE OF OPERATION
Chapter 12:CIRCUIT TECHNIQUES IN 405 LINE SETS
Chapter 13:GUIDANCE IN REPAIRING 405 LINE TELEVISIONS:
Appendix 1 to 5