Editing Acorn Risc PC 700 Maintenance Guide

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[[File:Acorn Risc PC 700 motherboard.jpg|thumb|360x360px|Acorn Risc PC 700 motherboard (board 1208,000) with 2 MB VRAM and RAM SIMMs fitted; IOMD and VIDC20, the two CPU-card sockets and the RISC OS 3.6 ROMs.]]

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.<ref name="chris700">Whytehead, Chris. [https://chrisacorns.computinghistory.org.uk/Computers/RiscPC700.html "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).</ref>

* 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.<ref name="trm">[[Acorn Risc PC Technical Reference Manual]] (Issue 1, September 1994; part 0497,057), Acorn Computers &mdash; 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.</ref> 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)'''.<ref name="trm" /> 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.<ref name="4corn">[https://www.4corn.co.uk/rpca7000.php "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.</ref>

== Common failure points ==

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{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Acorn Risc PC 700 &mdash; 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]] &mdash; the near-identical 600 procedure
* [[Acorn Risc PC Technical Reference Manual]]
* [[Capacitor Failure Symptoms]] · [[Recommended Tools]]

== References ==

<references />

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