Acorn Risc PC 700 Maintenance Guide

This guide covers preventive maintenance for the Acorn Risc PC 700 (launched July 1995). The 700 is an ARM710 machine that shares the Risc PC architecture and slice case with the Acorn Risc PC 600; the differences are the faster 40 MHz CPU card, RISC OS 3.60, VRAM and 16-bit sound as standard, and the revised 1208,000 main board. The maintenance priorities are the same as the 600: the mains PSU, the NiMH backup battery, and the leak-prone surface-mount electrolytic capacitors.

⚠️ Safety: mains PSU

The Risc PC 700 has a fan-cooled mains switch-mode PSU in the base slice. Disconnect the mains lead before removing the cover, and treat the PSU primary side as live; do not open the PSU module unless competent with mains switch-mode supplies (discharge the primary bulk capacitor first). Observe anti-static precautions for the CPU card, IOMD, VIDC20, ROMs, SIMMs and VRAM.

Opening, cleaning and reseating

The 700 opens the same way as the 600: release the twist-lock pins, lift the cover, remove the CPU card(s) and the drive/podule slice to reach the motherboard.^[1]

Brush and air-blow dust from the board, the PSU fan and vents, and the drives.
Reseat the CPU card(s), the DRAM SIMMs and the VRAM.
Clean the podule backplane connector, the network-card slot and the rear ports.

A broken front-flap spring (a cosmetic sag of the front flap) is common and does not affect operation.

⚠️ NiMH backup battery and capacitor leakage

The 700 uses the same on-board NiMH backup cell (BT1, 1.2 V) and the same surface-mount aluminium electrolytic capacitors as the 600.^[2] Both leak with age. Inspect BT1 and the surface-mount electrolytics for leaked electrolyte and corrosion; clean and repair, replace the battery, and recap the board. Full list and procedure: Acorn Risc PC 700 Capacitor Guide.

On-board fuses

The motherboard carries surface-mount fuses FS1 (2 A) and FS2 (800 mA).^[2] A subsystem that is dead while the main rails are healthy can be a blown on-board fuse; check them for continuity.

Storage

The 700 has on-board IDE and floppy (and optional CD-ROM). It ships with RISC OS 3.60, which supports ADFS hard discs larger than 512 MB (up to 128 GB), so larger replacement IDE drives, CompactFlash or SD adapters can be fitted without an OS upgrade.^[3]

Common failure points

**Acorn Risc PC 700 — failure-prone items**
Item	Symptom	Action
Surface-mount electrolytics	Progressive/intermittent faults, corrosion	Recap; clean residue; repair tracks
NiMH battery (BT1)	Lost config/clock; corrosion	Clean, repair tracks, replace cell
Mains PSU module	Dead, random resets, fan/thermal issues	Check rails and fan; service or exchange the PSU
On-board fuses FS1/FS2	A subsystem dead with rails present	Check FS1 (2 A) and FS2 (800 mA) continuity
CPU card / SIMM / VRAM seating	Won't start, RAM errors	Reseat the CPU card, SIMMs and VRAM
IDE hard disc	Won't spin up, boot errors	Replace drive (RISC OS 3.60 supports large discs)

Recommended tools

Posidrive/Philips screwdrivers and an anti-static strap.
DC multimeter (rail and fuse checks); oscilloscope for bus-level work.
Hot-air or fine-tip soldering equipment, solder wick, flux and isopropyl alcohol for the recap and battery/track repair.
Replacement NiMH cell (or coin-cell modification) and a replacement IDE drive or solid-state adapter.

See Recommended Tools for the general toolkit.

Preventive maintenance checklist

Inspect/replace the NiMH battery (BT1); clean any corrosion.
Recap the surface-mount electrolytics and clean the board (Acorn Risc PC 700 Capacitor Guide).
Verify the PSU rails and fan; check FS1/FS2.
Reseat the CPU card, SIMMs and VRAM; clean the backplane contacts.
Back up and assess the IDE drive.

Related pages

Acorn Risc PC 700
Acorn Risc PC 700 Troubleshooting Guide
Acorn Risc PC 700 Capacitor Guide
Acorn Risc PC 600 Maintenance Guide — the near-identical 600 procedure
Acorn Risc PC Technical Reference Manual
Capacitor Failure Symptoms · Recommended Tools

References

↑ Whytehead, Chris. "Acorn Risc PC 700", Chris's Acorns / The Centre for Computing History. Source for the 40 MHz ARM710, RISC OS 3.60, VRAM/16-bit sound as standard, and the board part number (1208,000).
↑ ^2.0 ^2.1 Acorn Risc PC Technical Reference Manual (Issue 1, September 1994; part 0497,057), Acorn Computers — hosted on this wiki. Documents the Risc PC architecture (IOMD, VIDC20, FDC37C665), the on-board fuses FS1 (2 A) and FS2 (800 mA), the NiMH battery, the main-PCB parts list and the Power On Self Test. The parts list covers the original 0197,000 board; the 700's 1208,000 board is a revision.
↑ "The Acorn Risc PC and A7000", 4corn Computers. Source for RISC OS 3.60 raising the ADFS disc limit to 128 GB, and the Risc PC architecture/CPU-card detail.

[chris700-1] Whytehead, Chris. "Acorn Risc PC 700", Chris's Acorns / The Centre for Computing History. Source for the 40 MHz ARM710, RISC OS 3.60, VRAM/16-bit sound as standard, and the board part number (1208,000).

[trm-2] 2.0 ^2.1 Acorn Risc PC Technical Reference Manual (Issue 1, September 1994; part 0497,057), Acorn Computers — hosted on this wiki. Documents the Risc PC architecture (IOMD, VIDC20, FDC37C665), the on-board fuses FS1 (2 A) and FS2 (800 mA), the NiMH battery, the main-PCB parts list and the Power On Self Test. The parts list covers the original 0197,000 board; the 700's 1208,000 board is a revision.

[4corn-3] "The Acorn Risc PC and A7000", 4corn Computers. Source for RISC OS 3.60 raising the ADFS disc limit to 128 GB, and the Risc PC architecture/CPU-card detail.

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