Editing Amiga 1200 Maintenance Guide

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[[File:Commodore Amiga 1200.jpg|thumb|360px|Amiga 1200]]
Routine care for the '''[[Amiga 1200]]'''. As on the [[Amiga 600]], the most important job is replacing the leaking surface-mount electrolytics, covered in the [[Amiga 1200 Capacitor Replacement Guide]]. For fault-finding see the [[Amiga 1200 Troubleshooting Guide]].

== Inspection ==
* Look round every electrolytic for residue, discoloured solder mask and green vias, and check the via under C334 in particular: on one board it had rotted through and left Paula's audio ground floating.<ref name="pure">Pure Amiga, {{cite web |url=https://www.pureamiga.co.uk/2024/05/13/repair-notes-a1200-stuck-right-mouse-button/ |title=Repair notes: A1200 stuck right mouse button, audio clicks |date=13 May 2024 |access-date=2026-10-01}}</ref>
* If the board has been recapped before, check that the capacitors are the right way round. LinuxJedi found almost every surface-mount capacitor on one A1200 soldered in backwards by an earlier repair.<ref name="ljrecap">LinuxJedi, {{cite web |url=https://linuxjedi.co.uk/why-recapping-isnt-always-the-cure-and-amiga-1200-repair-story/ |title=Why recapping isn't always the cure: an Amiga 1200 repair story |access-date=2026-10-01}}</ref>
* Note the board revision, printed on the board, and the Budgie revision; both matter for accelerator compatibility (see the troubleshooting guide).<ref name="bboah">{{cite web |url=https://bigbookofamigahardware.com/bboah/product.aspx?id=13 |title=Commodore A1200 |website=Big Book of Amiga Hardware |access-date=2026-10-01}}</ref>

== Power supply ==
The A1200 shares the A600's external supply: Commodore part 391029, rated 3.0 A at +5 V, 0.5 A at +12 V and 0.1 A at −12 V, 22.2 W.<ref name="hwb">{{cite web |url=https://www.hardwarebook.info/Amiga_500-600-1200_Power_Supply |title=Amiga 500/600/1200 power supply |website=The Hardware Book |access-date=2026-10-01}}</ref> That is little margin for expansions. Ian Stedman measured an A1200 with a 68060 card, two hard drives and a SCSI card drawing 3.0 A on +5 V, and Wikipedia notes that hard disks and even external floppy drives can stress the supply.<ref name="stedman">Ian Stedman, {{cite web |url=https://www.ianstedman.co.uk/amiga-power-supply-guide/ |title=Amiga power supply guide |access-date=2026-10-01}}</ref><ref name="wp">{{cite web |url=https://en.wikipedia.org/wiki/Amiga_1200 |title=Amiga 1200 |website=Wikipedia |access-date=2026-10-01}}</ref> Wikipedia gives the common remedy as a higher-rated supply such as the A500's.<ref name="wp" />

Inside, World of Jani found these capacitors in a 391029-03: a 47 µF 385 V reservoir on the mains side, three 1000 µF 10 V, three 82 µF 35 V, a 330 µF 10 V, a 1 µF 35 V and a 1 µF 50 V, all originally low-ESR. The same page warns that the line-filter capacitors, RIFA parts in particular, are "prone to release out the magic smoke".<ref name="jani">{{cite web |url=https://blog.worldofjani.com/?p=5695 |title=Amiga 500/600/1200 Powersupply capacitor list |website=World of Jani |date=4 January 2021 |access-date=2026-10-01}} (secondary source).</ref> The reservoir capacitor holds a mains-derived charge after unplugging; discharge it before working inside.

== Clock batteries on expansion cards ==
The A1200 main board has no clock or battery.<ref name="bboah" /> Clocks were added on trapdoor RAM and accelerator cards.<ref name="wpcp">{{cite web |url=https://en.wikipedia.org/wiki/Clock_port |title=Clock port |website=Wikipedia |access-date=2026-10-01}} "The clock was typically added by other means (usually integrated on CPU or RAM expansions)."</ref> Rechargeable NiCd and NiMH cells on Amiga expansion cards leak corrosive electrolyte as they age.<ref name="serveftp">{{cite web |url=http://amiga.serveftp.net/Battery.html |title=RTC battery replacement |website=Amiga Technical Resource (amiga.serveftp.net) |access-date=2026-10-01}}</ref> Take any trapdoor card out, inspect its battery, and remove one that has started to leak. See [[Battery Explosion, Capacitor or Corrosion Damage]] and [[Battery Refurbishment]].

== Keyboard ==
The A1200 keyboard uses conductive pads on rubber plungers against a membrane. Measured across a pad, good ones read around 100 Ω and bad ones over 500 Ω in one restorer's tests;<ref name="modrobert">{{cite web |url=https://modrobert.org/2025/08/23/repairing-the-amiga-1200-keyboard/ |title=Repairing the Amiga 1200 keyboard |website=modrobert weblog |date=23 August 2025 |access-date=2026-10-01}}</ref> another treats 80 Ω or lower as good, measured with light pressure on the 200 Ω range, and restores worn pads with aluminium tape.<ref name="icomp">{{cite web |url=https://forum.icomp.de/index.php?thread%2F2647-amiga-a1200-keyboard-cheap-fix%2F= |title=Amiga A1200 keyboard cheap fix |website=Individual Computers forum |access-date=2026-10-01}}</ref> The membrane itself must be intact for a pad repair to help.<ref name="icomp" />

== Floppy drive ==
Escom-built machines used PC drives that "do not supply a 'ready' signal", which caused compatibility problems; Escom released a free circuit upgrade for it.<ref name="wp" /> On an Escom A1200 with drive problems, check whether that fix has been made. For mechanical cleaning see [[Floppy Drive Repair]].

== Hard drive, CompactFlash and PCMCIA ==
* With the original scsi.device driver in Kickstart 3.1 and earlier, drives and cards are limited to 7.87 GiB by CHS addressing.<ref name="cfFAQ">{{cite web |url=https://www.amibay.com/threads/cf-sd-and-large-drives-faq.20481/ |title=CF / SD and large drives FAQ |website=AmiBay forum |access-date=2026-10-01}}</ref>
* A CompactFlash adapter that only supports cable select will not show a second (slave) device.<ref name="bboah" />
* Gayle fails to reset a PCMCIA card during a system reset. The fixes are the CardReset software or a small adapter fitted to Gayle.<ref name="lyons">Lyonsden, {{cite web |url=https://lyonsden.net/a1200-pcmcia-reset-bug-hardware-fix/ |title=A1200 PCMCIA reset bug: hardware fix |access-date=2026-10-01}}</ref>

== Ports ==
Do not plug or unplug joysticks or mice with the machine on; a connector shell can short a pin and damage a resistor or a CIA.<ref name="sukko">SukkoPera, {{cite web |url=https://github.com/SukkoPera/OpenAmigaJoyMouseSwitcher |title=OpenAmigaJoyMouseSwitcher |website=GitHub |access-date=2026-10-01}}</ref> On Rev. 2B boards the +12 V pin of the RGB port is not connected, so a genlock needs its own supply.<ref name="resource">{{cite web |url=http://amiga.resource.cx/mod/a1200.html |title=Amiga 1200 |website=Amiga Hardware Database (amiga.resource.cx) |access-date=2026-10-01}}</ref>

== Related pages ==
* [[Amiga 1200]]
* [[Amiga 1200 Capacitor Replacement Guide]]
* [[Amiga 1200 Troubleshooting Guide]]
* [[Amiga 1200 Schematics]]
* [[Recommended Tools]]

== References ==
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[[Category:Commodore Systems]]
[[Category:Maintenance Guides]]