Sinclair Research ZX Spectrum User Manual

SERVICING MANUAL
FOR
ZX SPECTRUM®
• LIST OF CONTENTS
INTRODUCTION
SECTION 1 SYSTEM DESCRIPTION
SECTION 2 DISASSEMBLY/ASSEMBLY
SECTION 3 SETTING UP AND SYSTEM TEST
SECTION 4 FAULT DIAGNOSIS AND REPAIR
SECTION 5 PARTS LISTS
i LIST OF ILLUSTRATIONS i
Fig No.
ZX Spectrum Block Diagram 1.1
Expansion RAM RAS/CAS Timing (Read Cycle shown) 1.2
Keyboard Matrix Interconnections 1.3
ZX Spectrum (Issue 2) Circuit Diagram 1.4
ZX Spectrum (Issue 3) Circuit Diagram 1.5
Keyboard Format 4.1
Speaker Load Input Waveforms 4.2
Expansion Memory 1C Locations 4.3
Issue 3 Links vs 1C Manufacturer and Type 4.4
Printed Circuit Board (Issue 2) Component Layout 5.1
Printed Circuit Board (Issue 3) Component Layout 5.2
Printed Circuit Board (Issue 3B) Component Layout 5.3
Prepared by THORN (EMI) DATATECH LTD
for SINCLAIR RESEARCH LTD MARCH 1984
© Sinclair Research Ltd.
(i)

Sinclair Research ZX Spectrum Specifications

General

Manufacturer	Sinclair Research
Release Year	1982
CPU	Zilog Z80A
CPU Clock Speed	3.5 MHz
RAM	16 KB or 48 KB
ROM	16 KB
Graphics Resolution	256 x 192 pixels
Operating System	Sinclair BASIC
Power	9V DC
Colors	8 (with brightness control)
Sound	1 channel
Storage	Cassette tape
Keyboard	Rubber keyboard
Ports	expansion
Colours	8 colours with 2 shades each (normal and bright)

Summary

ZX Spectrum System Description

Introduction and Architecture

Overview of the ZX Spectrum's system, architecture, and main components.

CPU and Memory Details

Details on the Z80A CPU, memory organisation, and read/write operations.

Input/Output Functions

Covers TV picture generation, keyboard scanning, tape interface, and power supplies.

ZX Spectrum Disassembly and Assembly

Disassembly Procedure

Step-by-step guide to disassembling the ZX Spectrum computer case.

Assembly Procedure

Instructions for reassembling the ZX Spectrum computer case.

ZX Spectrum Setup and System Test

General Alignment and Voltage Checks

Introduction to setting up, checking power voltages, and colour bias.

Oscillator Adjustments

Procedures for adjusting the sub-carrier and 14 MHz oscillators.

System Test Procedure

Procedure for testing the Spectrum's circuitry using a ZXTP taped program.

ZX Spectrum Fault Diagnosis and Repair

Introduction and Modifications

Overview of fault finding, test equipment, and historical board modifications.

Diagnosis Techniques

General techniques, power supply checks, initialisation, memory, and keyboard fault finding.

Fault-Finding Guide

Table of common symptoms and recommended actions for troubleshooting Spectrum faults.

ZX Spectrum Parts List

Introduction to Parts Lists

Introduction to parts lists for case and board assemblies.

Capacitor Replacements

Recommendation to replace certain disc capacitors with axial types in early Issue 2 units.