Josh: Add machine photo

2026-06-17T20:54:20Z

Add machine photo

← Older revision		Revision as of 21:54, 17 June 2026
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			[[File:Acorn System 2.jpg\|thumb\|360x360px\|Acorn System 2 in a 19-inch Eurocard card frame.]]

	This guide covers recapping the '''[[Acorn System 2]]''' (1980). The System 2 is a set of Eurocards, so the capacitors are per-card: each card carries ceramic decouplers plus a single electrolytic on its +5 V regulator. The exact per-card values are in the card circuit diagrams and the [[Acorn System Catalogue]]; the CPU and cassette cards use the verified [[Acorn System 1]] values.<ref name="cat">[[Acorn System Catalogue]] and [[Acorn System 1 Technical Manual]], Acorn Computers — hosted on this wiki. Source for the Eurocard set and the System 1 CPU/cassette-card capacitor values (a 15 µF/16 V electrolytic plus ceramic decouplers per card).</ref>		This guide covers recapping the '''[[Acorn System 2]]''' (1980). The System 2 is a set of Eurocards, so the capacitors are per-card: each card carries ceramic decouplers plus a single electrolytic on its +5 V regulator. The exact per-card values are in the card circuit diagrams and the [[Acorn System Catalogue]]; the CPU and cassette cards use the verified [[Acorn System 1]] values.<ref name="cat">[[Acorn System Catalogue]] and [[Acorn System 1 Technical Manual]], Acorn Computers — hosted on this wiki. Source for the Eurocard set and the System 1 CPU/cassette-card capacitor values (a 15 µF/16 V electrolytic plus ceramic decouplers per card).</ref>

Josh: Create Acorn System series page (cited; sourced from System manuals/catalogue)

2026-06-17T20:53:09Z

Create Acorn System series page (cited; sourced from System manuals/catalogue)

New page

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This guide covers recapping the '''[[Acorn System 2]]''' (1980). The System 2 is a set of Eurocards, so the capacitors are per-card: each card carries ceramic decouplers plus a single electrolytic on its +5 V regulator. The exact per-card values are in the card circuit diagrams and the [[Acorn System Catalogue]]; the CPU and cassette cards use the verified [[Acorn System 1]] values.<ref name="cat">[[Acorn System Catalogue]] and [[Acorn System 1 Technical Manual]], Acorn Computers — hosted on this wiki. Source for the Eurocard set and the System 1 CPU/cassette-card capacitor values (a 15 µF/16 V electrolytic plus ceramic decouplers per card).</ref>

== Approach ==

The System 2 has no mains and no CRT on its cards (only the optional Acorn PSU is mains-powered). Capacitor work is low-risk per-card bench work. On each Eurocard:

* The recap target is the '''regulator electrolytic''' (the CPU and cassette cards use 15 µF/16 V; the VDU and memory cards each have their own regulator electrolytic).
* The ceramic decouplers are stable and are left in place.

== CPU and cassette cards ==

These are the [[Acorn System 1]] cards. Their full capacitor lists are in the [[Acorn System 1 Capacitor Replacement Guide]]; the only electrolytic on each is a '''15 µF/16 V''' part (C10 on the CPU card, C5 on the cassette card).

== VDU and memory cards ==

The 40×25 VDU card and the memory (RAM + BASIC ROM) card each regulate their own +5 V and carry a regulator electrolytic plus ceramic decouplers. Read each value from the card itself and the card circuit diagram before replacing. Replace any electrolytic with a 105 °C low-ESR part of equal capacitance and equal-or-higher voltage, observing polarity.

== Procedure ==

# Power off; remove the card from the backplane.
# Record the value, voltage and polarity of each electrolytic.
# Desolder, clean the holes, fit the new part with correct polarity, solder and trim.
# Verify +5 V on the card and refit.

== Optional mains PSU ==

If an Acorn mains power supply is fitted, it has its own bulk smoothing electrolytics (and mains-side parts). Recap it only if competent with mains supplies; discharge the bulk capacitor first.

== Related pages ==

* [[Acorn System 2]]
* [[Acorn System 2 Maintenance Guide]]
* [[Acorn System 2 Troubleshooting Guide]]
* [[Acorn System 1 Capacitor Replacement Guide]] · [[Capacitor Failure Symptoms]]

== References ==

<references />

{{Navbox-AcornComputers|state=collapsed}}

[[Category:Acorn Computers]]
[[Category:Capacitor Replacement Guides]]

Acorn System 2 Capacitor Replacement Guide - Revision history

Josh: Add machine photo

Josh: Create Acorn System series page (cited; sourced from System manuals/catalogue)