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Acorn A3000 Service Manual

From RetroTechCollection

The A3000 Service Manual is Acorn Computers' own dealer service manual for the Acorn Archimedes A3000, part number 0480,050, Issue 1, published September 1989 by Acorn Computers Technical Publications Department. 57 pages, with a text layer and searchable.

Contents

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

  • System description — 5: introduction and general 5, the I/O system 6, the sound system 13, the keyboard and mouse 14, floppy disc drive 19, power supply 19, links 20, plugs 21, sockets 21, changes between Issue A and Issue 1 PCBs 23
  • A3000 expansion — 25: internal expansion 25, external expansion 29
  • Disassembly and reassembly — 31
  • Fault diagnosis — 33: checking a "dead" computer 34, functional tests 36, main computer tests 38, upgrade tests 42
  • Main PCB fault diagnosis & repair — 45: system failure 46, video faults 46, peripheral faults 47, test ROMs 48
  • Parts lists — 51
  • Appendix A: serial port loopback plug — 55; Appendix B: earth continuity testing — 57
  • Drawings: A3000 final assembly diagram, User Port / MIDI circuit diagram, internal upgrade diagram, external podule fixing diagram

The parts lists are the reason to reach for this manual rather than the technical reference: the PCB assembly parts list gives Acorn part number, description and quantity against every designator on the board — resistors, capacitors (ceramic, plate, polyester, tantalum and aluminium electrolytic, each with value and voltage), transistors, diodes, inductors, sockets and links — and marks positions Acorn left unstuffed as N/F. A separate final assembly parts list covers the mouldings, keyboard, disc drive, PSU and cables.

What it settles

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  • The A3000's real-time-clock cell is B1, "BAT NICAD 1V2 280mAH PCB", Acorn part 0817,013 — a 1.2 V nickel-cadmium cell soldered to the main PCB, not a battery holder and not a lithium cell. The manual's disassembly chapter says plainly that replacing it needs a soldering iron and a desoldering gun.
  • LK5 is a connection point for an external battery, provided, in Acorn's words, only "if supply of on board NiCad becomes a problem".
  • Acorn's own RTC test: with the computer powered off, look for about 1.1 V on IC6 pin 8. If the voltage is absent, check R3 and R7; if it is below 1 V, replace B1 and check D2 and C15. If the clock runs but runs badly, X2 is the suspect and LK7 gives access to the clock signal.

What this manual does not contain

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  • No component values for the power supply. The final assembly parts list carries the PSU as a single exchange item — a 22 W 240 V unit, one line, one part number — and the manual's only PSU instruction is how to replace the whole module, including the reminder to refit the plastic insulating film underneath it. Acorn published no component-level data for this supply.
  • No keyboard or mouse parts list at component level.
  • No full schematic in this volume: only the User Port / MIDI circuit diagram is included. The main PCB circuit diagram is bound separately with the Acorn A3000 Technical Reference Manual.
  • No coverage of the A3010, A3020, A4000 or A5000.

Pages that cite this document

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Download here: Acorn A3000 Service Manual.pdf

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