Josh: Create Acorn Archimedes A3010/A3020 page set (researched, cited)

2026-07-18T13:44:50Z

Create Acorn Archimedes A3010/A3020 page set (researched, cited)

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[[File:Acorn Archimedes A3010 motherboard.jpg|thumb|360x360px|Acorn A3010 main PCB (0195,200 Issue 1). The ARM250 is the large square package centre-board; the two 9-pin joystick ports run along the top edge, the RISC OS ROMs are to the right, and the on-board mains PSU (transformer and suppression capacitor) is at the left. No IDE connector is fitted.]]

This guide covers preventive maintenance for the '''[[Acorn Archimedes A3010]]''' (ARM250 board, part 0195,200; early "Adelaide" boards are 0194,000). The A3010 is a single-box home machine with an on-board mains power supply, a floppy drive but no internal hard disc, and a highly integrated board. The maintenance priorities are the '''NiCd backup battery''', the '''on-board PSU''', and the '''audio hybrid card'''.

== ⚠️ Safety: on-board mains PSU ==

The A3010's mains power supply is built onto the main PCB, so '''the board carries mains voltages. Disconnect the mains lead before opening the case,''' and treat the power end of the board as a live hazard until it is proven discharged.<ref name="sm">[[Acorn A3010, A3020 and A4000 Service Manual]], Acorn Computers Ltd — hosted on this wiki. PSU-fail and main-PCB-fail routines, the 5 A mains fuse and internal fuse FS1, thermal shutdown, the +5 V/+12 V rails, drive-power links LK1/LK2, and the earth-continuity / DC-insulation safety tests.</ref> Re-apply the earth-continuity and DC-insulation (class 1) safety tests after any internal work.<ref name="sm" />

== The machine and its board ==

The ARM250 integrates the ARM2 core, MEMC1a, VIDC1a and IOC into one 12 MHz package. Early A3010s used the interim "Adelaide" board carrying the equivalent discrete chips; those boards can take an ARM3 upgrade, whereas the later ARM250 boards cannot.<ref name="arcwiki">[https://arcwiki.org.uk/index.php/A3010 "A3010"], Arc Wiki.</ref><ref name="chris">Whytehead, Chris. [https://chrisacorns.computinghistory.org.uk/Computers/A3010.html "Acorn A3010"], Chris's Acorns / The Centre for Computing History.</ref>

{| class="wikitable styled-table" style="width:90%; text-align:center;"
|+'''Acorn A3010 key facts'''
! Item !! Detail
|-
| Processor || ARM250 @ 12 MHz (ARM2 + MEMC1a + VIDC1a + IOC)
|-
| RAM || 1 MB base (2 MB official max; 4 MB with third-party boards)
|-
| ROM || RISC OS 3.10 or 3.11 (two devices)
|-
| Storage || 3.5" floppy (1.6 MB); no internal hard disc
|-
| Extras || UHF TV modulator; two 9-pin joystick ports
|-
| Expansion || one mini-podule slot (no network socket)
|-
| PSU || built onto the main PCB (+5 V, +12 V)
|-
| Board || 0195,200 (ARM250) / 0194,000 "Adelaide" (interim)
|}

== ⚠️ The backup battery — do this first ==

The A3010 keeps its configuration and clock in battery-backed CMOS RAM, using a soldered rechargeable NiCd cell near the RTC.<ref name="trm">[[Acorn A3010, A3020 and A4000 Technical Reference Manual]], Acorn Computers Ltd — hosted on this wiki. PCF8583 RTC, battery, DRAM-size links (LK20/LK21/LK22), reset circuit and per-designator values.</ref> As on every Acorn machine of this era, the cell leaks and corrodes the surrounding tracks, and this is the most common cause of a dead A3010.<ref name="stardotdead">[https://stardot.org.uk/forums/viewtopic.php?t=13260 "Dead A3010"], Stardot forums (battery-leak inspection, track continuity, ROM/RAM swap order).</ref> On any unrestored machine:

# '''Remove the battery immediately.'''
# Neutralise residue (white vinegar), then rinse with high-strength isopropyl alcohol.
# Inspect and buzz out every track around the battery and the RTC; repair any broken track.
# Fit a replacement using a coin-cell holder (for example a CR2032) '''with a series diode''' so the non-rechargeable cell cannot be back-charged.<ref name="retrorr">[https://retrorepairsandrefurbs.com/2024/09/27/1992-acorn-archimedes-3010-repair-restoration/ "1992 Acorn Archimedes A3010 repair/restoration"], Retro Repairs and Refurbs.</ref>

The '''PCF8583''' clock/calendar chip is the device most often killed by the leak; if it cannot be read the machine will not reach the desktop.<ref name="retrorr" />

== Opening and cleaning ==

# Unplug the mains lead and all peripherals.
# Remove the case screws and lift the top; disconnect the floppy data and power cables to free the board.<ref name="chris" />
# Brush and air-blow dust from the board and the floppy mechanism.
# Clean the mini-podule edge connector with a soft eraser; clean the keyboard, parallel, serial, joystick and video sockets with contact cleaner on a foam swab.

== Audio hybrid card ==

The A3010's sound output stage is on a small hybrid daughter-card next to the mini-podule slot. Two age-related problems affect it: the '''card's pins can fracture''' where it sits beside the slot (aggravated by any nearby battery corrosion), and its '''surface-mount electrolytic capacitors''' degrade, both giving crackle, pops or intermittent sound.<ref name="stardotaudio">[https://stardot.org.uk/forums/viewtopic.php?t=23343 "A3010/A4000 audio hybrid crackle"], Stardot forums.</ref> Reseat or resolder the hybrid's connector and, if the crackle persists, recap the hybrid's SMD electrolytics (see the [[Acorn Archimedes A3010 Capacitor Guide]]). A faint power-on "pop" is normal on some units.<ref name="stardotaudio" />

== Power supply checks ==

The on-board PSU delivers +5 V (logic and floppy) and +12 V (video-connector pin 12 for SCART).<ref name="sm" /> Acorn's "action if PSU fails" routine:

# Switch off and unplug the mains lead.
# Check the '''5 A fuse in the mains plug'''. If a replacement blows on switch-on, the supply is faulty.
# Check the internal fuse '''FS1''' and confirm the drive-power links '''LK1''' and '''LK2''' are fitted.
# If the supply runs then cuts out, suspect thermal shutdown; repeated shutdowns mean a faulty supply.

A machine that '''takes many attempts to power on''' or whose 5 V rail is out of spec usually has ageing PSU electrolytics; the problem worsens under added load such as a memory upgrade.<ref name="stardotpsu">[https://stardot.org.uk/forums/viewtopic.php?t=9696 "A3010 PSU electrolytics / slow to power on"], Stardot forums.</ref> Because the PSU is part of the main board, a PSU repair is a board-level job done with the mains disconnected and the primary capacitor discharged — see the [[Acorn Archimedes A3010 Capacitor Guide]].

== Capacitor health ==

The A3010 main board uses through-hole electrolytics with surface-mount ceramic decouplers, and is '''not''' affected by the surface-mount electrolyte leakage of the later Acorn machines; the audio hybrid card is the one place surface-mount electrolytics appear.<ref name="stardot10675">[https://stardot.org.uk/forums/viewtopic.php?t=10675 "Which Acorn machines leak"], Stardot forums.</ref> The recap priorities are the on-board PSU and the audio hybrid card. Full detail: [[Acorn Archimedes A3010 Capacitor Guide]].

== Functional and safety testing ==

Acorn's service procedure uses the ARM250 functional test software, which exercises audio, battery-backed RAM, floppy, external-port, joystick, keyboard/mouse, memory, real-time-clock, UHF-modulator and video subsystems and produces a test report.<ref name="sm" /> Re-apply the earth-continuity and DC-insulation safety tests after any repair.<ref name="sm" />

== Common failure points ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Acorn A3010 — failure-prone items'''
! Item !! Symptom !! Action
|-
| NiCd battery (near RTC) || Lost config/clock; corrosion || Remove, neutralise, repair tracks, fit CR2032 + series diode
|-
| PCF8583 RTC || Machine will not reach the desktop || Replace if killed by battery leakage
|-
| On-board PSU || Slow/failed power-on, out-of-spec 5 V, resets || Check plug fuse and FS1; discharge and recap the PSU section
|-
| Audio hybrid card || Crackle, pops, intermittent sound || Resolder pins / reseat connector; recap the hybrid's SMD electrolytics
|-
| Mini-podule edge connector || Expansion unreliable || Clean fingers; reseat
|-
| ARM250 || No combination of CPU/memory/video works || Whole-device replacement
|}

== Recommended tools ==

* Posidrive/Philips screwdrivers and an anti-static strap.
* DC multimeter for rail checks; oscilloscope for bus-level diagnosis.
* Isopropyl alcohol, white vinegar, foam swabs, soft eraser, contact cleaner.
* CR2032 holder and a small-signal diode for the battery conversion.
* Fine-tip temperature-controlled soldering iron and solder wick.
* Earth-continuity and insulation testers if returning the machine to service.

See [[Recommended Tools]] for the general toolkit.

== Preventive maintenance checklist ==

# Remove and replace the NiCd battery; neutralise and repair any corrosion.
# Check the plug fuse and FS1; verify the +5 V and +12 V rails and links LK1/LK2.
# Inspect and, if needed, resolder/recap the audio hybrid card.
# Clean the mini-podule edge connector and the floppy head.
# Re-apply the earth-continuity and insulation safety tests after any internal work.

== Related pages ==

* [[Acorn Archimedes A3010]]
* [[Acorn Archimedes A3010 Troubleshooting Guide]]
* [[Acorn Archimedes A3010 Capacitor Guide]]
* [[Acorn Archimedes A3020 Maintenance Guide]] — education sibling with an IDE hard disc and network socket
* [[Acorn A3010, A3020 and A4000 Service Manual]] · [[Acorn A3010, A3020 and A4000 Technical Reference Manual]]
* [[Capacitor Failure Symptoms]] · [[Recommended Tools]]

== References ==

<references />

{{Navbox-AcornComputers|state=collapsed}}

[[Category:Acorn Computers]]
[[Category:Maintenance Guides]]

Acorn Archimedes A3010 Maintenance Guide - Revision history

Josh: Create Acorn Archimedes A3010/A3020 page set (researched, cited)