Acorn Electron Service Manual

The Electron Service Manual is Acorn Computers' own dealer service manual for the Acorn Electron, part number 0405001, Issue 2, January 1987 (first published 1984). 54 pages, with a text layer and searchable.

Acorn states its audience plainly: "service engineers and Acorn dealers who will be servicing the Electron microcomputer on behalf of Acorn Computers Limited". The copyright page adds that the manual "remains the property of Acorn Computers at all times and must be returned to them immediately upon the termination of the dealer's appointment" — which is why so few copies survive.

Contents

Acorn's own contents list, with printed page numbers:

• 1 Introduction — 1
• 2 Packaging and installation — 2
• 3 Specification — 3: microcomputer 3, machine operating system 3, BASIC 4, power supply 4, cassette interface 4, video outputs 4 (modulated 4, composite 5, colour monitor 5), audio output 5, environment 5
• 4 Disassembly and assembly — 6
• 5 Circuit description — 7: general 7, PCB links 7
• 6 The uncommitted logic array (ULA) — 8
• 7 Electron test equipment — 9
• 8 Fault finding inside a dead Electron — 10: power supply 10, oscillator 10, ULA 10, CPU 11, ROM 11, DRAMs 11, video 11, cassette interface 13, keyboard 14, sound 14
• Appendix: diagnostic flowcharts 15, final assembly 25, Electron block diagram 27, functional block diagram of the Electron ULA 29, main PCB circuit diagram 31, main PCB layout 33, main PCB silk-screen 35, Electron power supply board circuit diagram 37, keyboard matrix 39, Electron parts lists 41

Why this one is unusually complete

Three things make it more useful than most machine service manuals of the period:

• §6 documents the ULA pin functions — the part most often blamed and least often verified. §8.3 gives Acorn's own test for it.
• §8 is a systematic dead-machine procedure in Acorn's own order: supply, oscillator, ULA, CPU, ROM, DRAM, video, cassette, keyboard, sound. The diagnostic flowcharts in the appendix follow the same order.
• Unlike the BBC Micro service manual, which carries the supply as a single exchange module, this manual does include a power supply board circuit diagram (page 37) alongside the main PCB diagram, layout and silk-screen.

What this manual does not contain

• No monitor or television coverage — the video outputs are specified, but display equipment is out of scope.
• No coverage of Plus 1, Plus 3 or third-party expansions.
• No component-level coverage of the Electron's external power brick beyond the supply board diagram and the §3.4 specification.
• Some PCB issues predate this edition; where a board does not match, the parts list is the arbiter.

Pages that cite this document

• Acorn Electron · Acorn Electron Maintenance Guide · Acorn Electron Troubleshooting Guide · Acorn Electron Capacitor Replacement Guide

Download here: Acorn Electron Service Manual.pdf