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Acorn A3000 Service Manual

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

Contents

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Acorn's contents list, with printed page numbers (the PDF page numbers match). For the main PCB chapter the printed contents are wrong: the test ROMs section starts on p. 47, video faults on p. 49 and peripheral faults on p. 50.

  • System description, p. 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, p. 25: internal expansion 25, external expansion 29
  • Disassembly and reassembly, p. 31
  • Fault diagnosis, p. 33: checking a "dead" computer 34, functional tests 36, main computer tests 38, upgrade tests 42
  • Main PCB fault diagnosis and repair, p. 45: system failure 46, video faults 46, peripheral faults 47, test ROMs 48
  • Parts lists, p. 51: final assembly, main PCB assembly, 2 MB RAM upgrade, User Port/MIDI upgrade
  • Appendix A, serial port loopback plug, p. 55
  • Appendix B, earth continuity testing, p. 57

The main PCB assembly parts list (pp. 51-53) gives the Acorn part number, description and quantity for every designator on the board, including each capacitor's value, voltage and type, and marks unfitted positions N/F. The upgrade lists on p. 54 do the same for the 2 MB RAM board and the User Port/MIDI board.

What it settles

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  • The power supply specification (p. 19): one +5 V output, 4.9-5.1 V at 0.5-4.4 A, ripple and noise 50 mV peak to peak, over-voltage threshold 5.8-7.0 V, 22 W continuous and 29 W surge. Input is 198-264 V at 47-53 Hz or 99-130 V at 57-63 Hz, selected by a link wire on the supply.
  • The real-time clock and CMOS RAM cell is B1, "BAT NICAD 1V2 280mAH PCB", Acorn part 0817,013 (p. 53). It is soldered to the PCB, and Acorn says replacing it needs a soldering iron and a desoldering gun (p. 32).
  • LK5 is a connection point for an external battery, "only used if supply of on board NiCad becomes a problem" (links table, p. 20).
  • Acorn's clock test (p. 49): with the computer switched off, IC6 pin 8 should read about 1.1 V. If the voltage is absent, check R3 and R7; if it is below 1 V, change B1 and check D2 and C15. If the clock fails to run or runs inaccurately, check X2; LK7 gives access to the clock signal.

What this manual does not contain

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  • No component-level data for the power supply. The final assembly parts list carries it as one line, item 8, "22W 240V PSU" (part 0180,010), and the manual's only instruction is how to remove and refit the whole unit, with its plastic insulating film (p. 32).
  • No component-level parts list for the keyboard or mouse.
  • No drawings. The contents page lists four drawings (final assembly, User Port/MIDI circuit, internal upgrade, external podule fixing) and notes that the main PCB circuit and assembly drawings are bound separately; none of them is in this scan, which ends at Appendix B on p. 57. The main PCB circuit diagram is hosted separately as sheet 1 and sheet 2.
  • Nothing on the A3010, A3020, A4000 or A5000.

Pages that cite this document

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Download: Acorn A3000 Service Manual.pdf

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