Editing Acorn A4 (section)

== Known problems ==

* The surface-mount electrolytic capacitors on the main board leak, and the leakage causes freezes, failure to start and corrosion. A full recap is the usual first step on an A4 that has not been serviced.<ref name="sd12316" /><ref name="sd25903">[https://stardot.org.uk/forums/viewtopic.php?t=25903 "Several A4 repairs"], stardot.org.uk forum thread, November 2022. IanJeffray: a full blind recap is the usual first step on a never-serviced A4, "the only machine where a full blind re-cap is a recommended course of action".</ref> See [[Acorn A4 Capacitor Guide]].
* The board-mounted backup cell B1 leaks and corrodes the board around it.<ref name="adam">Wilson, Adam. [https://retrorepairsandrefurbs.com/2024/09/21/1992-acorn-a4-laptop-repair-restoration-modifications/ "1992 Acorn A4 Laptop Repair, Restoration, & Modifications"], Adam's Vintage Computer Restorations, September 2024 (retrieved 2026-10-01). Board-mounted NiCd cell and surface-mount electrolytics both leak; recap with C134 pads lost; CMOS reset with Delete held at power-on; Conner hard disc sticking; CF adapter and IDEFS expansion ROM; battery pack of twelve Varta 1.2 V 1.4 Ah sub-C NiCd cells with a thermal fuse and two thermistors.</ref>
* Battery packs of this age are dead and often leaking. See [[Acorn A4 Maintenance Guide#Battery pack]].
* The two flexible display cables and the keyboard membrane cables are fragile.<ref name="chris" /><ref name="theodis">Markettos, Theo. [https://www.chiark.greenend.org.uk/~theom/riscos/a4/dismantle.html "Dismantling the A4 base as far as the motherboard"], Acorn A4 pages, 2005 (retrieved 2026-10-01).</ref>
* The original Conner 60 MB hard discs suffer from sticking heads.<ref name="adam" />
* The brightness and contrast knobs go missing; a 3D-printable replacement by Ian Jeffray is published under CC BY 4.0.<ref name="knob">Jeffray, Ian. "Acorn A4 laptop LCD knob", Thingiverse thing 4891969, June 2021, CC BY 4.0: replacement contrast and brightness knobs, "as these seem to go missing". Archived copy: [https://archive.org/details/thingiverse-4891969 archive.org/details/thingiverse-4891969].</ref>

The [[Acorn A4 Troubleshooting Guide]] covers each fault in detail.