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Amiga 1200 Capacitor Replacement Guide

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Commodore Amiga 1200 motherboard in case
An Amiga 1200 main board in the lower case

Most of the electrolytic capacitors on the Amiga 1200 main board are surface-mount aluminium parts, and on boards of this age they leak onto the board.[1] Commodore's schematic, drawn for the "A1200 REV 1->1D PCB", gives the capacitance of each position but no voltage ratings, and neither of the two Commodore documents at Amiga 1200 Schematics includes a parts list.[2] The list below therefore combines the values on Commodore's schematic with the ratings in kit sellers' lists, which are secondary sources. LinuxJedi finds the through-hole capacitors on these boards usually fine; it is the surface-mount ones that leak.[3]

What leaking capacitors do

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  • Hertell names bad composite output, bad audio, crackling or distorted audio, and machines that will not boot as the usual signs on the A600, A1200 and CD32.[1]
  • AmigaKit's list adds failure to boot, sound corruption, mouse, joystick and other ports not working, and IDE hard drives not booting.[4]
  • On one A1200 the right mouse button stopped working and the audio clicked when it was pressed. Paula's audio ground (pin 37) sat at about 2.8 V because the via under C334 that joins it to ground had "totally rotted through". A wire through the via restored it.[5]

Hertell finds vias the most common place for this damage and repairs them by passing a wire through.[1]

Capacitor list

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A1200 main board electrolytics[6]
Ref Capacitance Console5 rating[7] Retro Rewind rating[8] Notes
C214 10 µF 35 V 25 V
C306 10 µF 35 V On the audio reference AVREF (schematic sheet 6)[2]
C407 10 µF 35 V 25 V Video supply (schematic sheet 6)[2]
C460 10 µF "NONE" Not listed Drawn beside C459 at U12; fitted on some boards only (see below)[6]
C303, C304, C459 22 µF 35 V 35 V
C324, C334 22 µF 35 V 16 V Audio output coupling, drawn as non-polarised (22UF-NP) on Commodore's schematic[2]
C821, C822 47 µF 16 V 16 V
C235, C236, C239, C409 100 µF 6 V 6.3 V C409 is at the video DAC (sheet 6)[2]
C237 470 µF 16 V 16 V Through-hole[8]
C307 470 µF 10 V 16 V Through-hole; Paula's supply (sheet 6)[2][8]
C408, C811 1000 µF 10 V 10 V Through-hole; C408 feeds the video supply (sheet 6)[8][2]

Retro Rewind lists C305 as a 10 µF electrolytic where the others have C306. On Commodore's schematic C305 is a 0.22 µF capacitor beside C306, and an Amiga.org thread on Rev. 1 boards agrees it is a 220 nF ceramic.[2][9] Do not fit an electrolytic at C305.

Kit lists are sold as covering every revision (1A, 1B, 1D.1, 1D.3, 1D.4 and 2B).[4] Commodore's schematic covers Rev. 1 to 1D only, so it does not show any Rev. 2B changes. Two revision differences are reported:

  • C460 is a 10 µF electrolytic on Commodore's schematic, but it is not fitted on every board. A reader of Hertell's guide reports it fitted on Rev. 1B, and Console5 lists it as empty;[6][1][7] the Big Book of Amiga Hardware records a Rev. 1D board that came from the factory with a 10 µF 16 V part there.[10]
  • On some 2B boards C407 is a tantalum; Hertell leaves it in place.[1]

C324 and C334

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Commodore draws both as non-polarised 22 µF capacitors, with the + end towards the LF347 (U15) output.[2] On some boards the silkscreen is printed backwards, or the factory fitted them the wrong way round. Console5 advises fitting the positive side to U15, or fitting non-polarised parts.[7] A polarised part fitted to the + marking on Commodore's drawing is correct.

Procedure

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  1. Remove the board, photograph both sides, and record the polarity of every electrolytic.
  2. Remove the surface-mount parts with hot air or hot tweezers, without force. Hertell works at about 280 °C and warns that twisting or cutting the parts off stresses the board.[1] Recap A Mac's notes warn to take great care not to melt anything nearby.[11]
  3. Clean off all old electrolyte; Hertell uses an ultrasonic cleaner.[1] Check the vias under C334 and the other positions for continuity, and repair broken ones with wire.[5]
  4. Fit surface-mount parts on surface-mount pads. An Amiga.org contributor advises against substituting radial parts.[9]
  5. Check the polarity of every new part against your photographs and the schematic before power-up. LinuxJedi repaired an A1200 on which almost every surface-mount capacitor from an earlier recap had been soldered in backwards.[3]
  6. Power up and test both audio channels, composite and RF video, the mouse and joystick ports, and the floppy and IDE interfaces.
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 John "Chucky" Hertell, Recapping, doing it right. Complete guide how to do it, 2016—link(accessed 2026-10-01) With replies to readers' comments.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Commodore, A1200 main board schematic 364717, "A1200 REV 1->1D PCB" (1992), hosted at Amiga 1200 Schematics. Sheet 6 of 13 (PDF p. 10 of the large-format scan): C305 0.22 µF, C306 10 µF, C307 470 µF, C407 10 µF, C408 1000 µF, C409 100 µF. Audio output sheet (PDF p. 9): C324 and C334 "22UF-NP".
  3. ↑ 3.0 3.1 LinuxJedi, Why recapping isn't always the cure: an Amiga 1200 repair story—link(accessed 2026-10-01)
  4. ↑ 4.0 4.1 AmigaKit, A1200 capacitor pack for professional recapping—link(accessed 2026-10-01)
  5. ↑ 5.0 5.1 Pure Amiga, Repair notes: A1200 stuck right mouse button, audio clicks, 13 May 2024—link(accessed 2026-10-01)
  6. ↑ 6.0 6.1 6.2 Commodore, A1200 main board schematic 364717 (Rev. 1 to 1D), "Composite" sheet, in the System Schematics Service Addendum, A1200 (1992), PDF p. 4: C214 10 µF, C235, C236 and C239 100 µF, C237 470 µF, C459 22 µF and C460 10 µF, all drawn as polarised electrolytics round the CXA1145 encoder (U12); "Power input" sheet in the large-format scan, PDF p. 16: C821 and C822 47 µF. Hosted at Amiga 1200 Schematics.
  7. ↑ 7.0 7.1 7.2 Console5 TechWiki, Amiga 1200—link(accessed 2026-10-01) Capacitor list (secondary source; a community list read from boards). C460 is given as "NONE".
  8. ↑ 8.0 8.1 8.2 8.3 Retro Rewind, A1200 cap list—link(accessed 2026-10-01) (secondary source).
  9. ↑ 9.0 9.1 A1200 audio decoupling capacitor—link(accessed 2026-10-01)
  10. ↑ Commodore A1200—link(accessed 2026-10-01)
  11. ↑ Recap A Mac, Amiga 1200—link(accessed 2026-10-01)
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