Amiga 1200 Maintenance Guide
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
[edit | edit source]- 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.[1]
- 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.[2]
- Note the board revision, printed on the board, and the Budgie revision; both matter for accelerator compatibility (see the troubleshooting guide).[3]
Power supply
[edit | edit source]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.[4] 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.[5][6] Wikipedia gives the common remedy as a higher-rated supply such as the A500's.[6]
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".[7] The reservoir capacitor holds a mains-derived charge after unplugging; discharge it before working inside.
Clock batteries on expansion cards
[edit | edit source]The A1200 main board has no clock or battery.[3] Clocks were added on trapdoor RAM and accelerator cards.[8] Rechargeable NiCd and NiMH cells on Amiga expansion cards leak corrosive electrolyte as they age.[9] 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
[edit | edit source]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;[10] another treats 80 Ω or lower as good, measured with light pressure on the 200 Ω range, and restores worn pads with aluminium tape.[11] The membrane itself must be intact for a pad repair to help.[11]
Floppy drive
[edit | edit source]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.[6] 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
[edit | edit source]- With the original scsi.device driver in Kickstart 3.1 and earlier, drives and cards are limited to 7.87 GiB by CHS addressing.[12]
- A CompactFlash adapter that only supports cable select will not show a second (slave) device.[3]
- Gayle fails to reset a PCMCIA card during a system reset. The fixes are the CardReset software or a small adapter fitted to Gayle.[13]
Ports
[edit | edit source]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.[14] On Rev. 2B boards the +12 V pin of the RGB port is not connected, so a genlock needs its own supply.[15]
Related pages
[edit | edit source]- Amiga 1200
- Amiga 1200 Capacitor Replacement Guide
- Amiga 1200 Troubleshooting Guide
- Amiga 1200 Schematics
- Recommended Tools
References
[edit | edit source]- ↑ Pure Amiga, Repair notes: A1200 stuck right mouse button, audio clicks, 13 May 2024—link(accessed 2026-10-01)
- ↑ LinuxJedi, Why recapping isn't always the cure: an Amiga 1200 repair story—link(accessed 2026-10-01)
- ↑ 3.0 3.1 3.2 Commodore A1200—link(accessed 2026-10-01)
- ↑ Amiga 500/600/1200 power supply—link(accessed 2026-10-01)
- ↑ Ian Stedman, Amiga power supply guide—link(accessed 2026-10-01)
- ↑ 6.0 6.1 6.2 Amiga 1200—link(accessed 2026-10-01)
- ↑ Amiga 500/600/1200 Powersupply capacitor list, 4 January 2021—link(accessed 2026-10-01) (secondary source).
- ↑ Clock port—link(accessed 2026-10-01) "The clock was typically added by other means (usually integrated on CPU or RAM expansions)."
- ↑ RTC battery replacement—link(accessed 2026-10-01)
- ↑ Repairing the Amiga 1200 keyboard, 23 August 2025—link(accessed 2026-10-01)
- ↑ 11.0 11.1 Amiga A1200 keyboard cheap fix—link(accessed 2026-10-01)
- ↑ CF / SD and large drives FAQ—link(accessed 2026-10-01)
- ↑ Lyonsden, A1200 PCMCIA reset bug: hardware fix—link(accessed 2026-10-01)
- ↑ SukkoPera, OpenAmigaJoyMouseSwitcher—link(accessed 2026-10-01)
- ↑ Amiga 1200—link(accessed 2026-10-01)