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8bit_ula proudly presents...

The Lil Old ZX Spectrum 48k Service Manual

LIST OF CONTENTS

SECTION 1 - INTRODUCTION

• Introduction
• Architecture
• Z80A CPU
• Memory Organisation
• Read/Write Operations
• Input/Output
• TV Picture Generation
• Keyboard Scanning
• Tape Interface
• Power Supplies

SECTION 2 - DISASSEMBLY/ASSEMBLY

• Disassembly
• Assembly

SECTION 3 - SETTING UP AND SYSTEM TEST

• General Alignment
• Introduction
• Voltage Check
• Colour Adjustment
• Sub-Carrier Oscillator
• 14MHz Oscillator
• System Test

SECTION 4 - FAULT DIAGNOSIS AND REPAIR

• Introduction
• Test Equipment
• Modification History
• Modifications - Issue 1 Board
• Modifications - Issue 2 Board
• 32k Extension Memory - (16k-48k)
• Hitachi vs NEC ROM
• Fault Diagnosis
• Techniques
• Power Supply Unit
• Initialisation
• Memory Check
• Keyboard Structure
• Fault-Finding Guide
• IC14 (LM1889) Pin Signals
• Repair
• 16k to 48k Upgrade
• Integrated Circuits/Link Settings
• Issue 2 Board
• Issue 3 Board

SECTION 5 - PARTS LISTS

• Introduction
• Notes to List for Issues 2, 3 and 3B

SUPPLEMENT NO. 1

• Introduction
• DC-DC Converter Modification
• Issue 3B Board
• Issue 4 Board
• Issue 4A Board
• Issue 4B Board
• Issue 5 Board
• Issue 6 Board
• Issue 6A Board
• Fault-Finding - Servicing Addenda
• Warranty Seal
• Parts Lists

SUPPLEMENT NO. 2

• Introduction
• Conversion Procedure - Spectrum to Spectrum +
• Assembly of the Keyboard for the Spectrum +
• Keyboard Operation
• Spectrum+ Keyboard : Top Membrane Diagram
• Spectrum+ Keyboard : Lower Membrane Diagram

Downloaded from The Lil Old Sinclair Technical Information Repository

Electronic mail to zx_8bit_ula@hotmail.com