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Macintosh Centris 660AV Capacitor Replacement Guide

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Capacitor replacement for the Macintosh Centris 660AV, renamed Quadra 660AV in October 1993; the two are the same machine and Apple services them from one Service Source volume.[1] Unlike the Macintosh Centris 650, this machine's logic board carries surface-mount aluminium electrolytic capacitors.[2]

What fails

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Surface-mount electrolytics of this age leak a corrosive electrolyte that eats through the traces, pads and component pins around them, and a board with leaking capacitors has to be recapped before it can be restored.[3] MacDat lists all thirteen on this board for replacement.[4] Look at each one under magnification for brown residue, a dark, glossy halo or white-green deposits on the nearby pads, and clean anything you find with isopropyl alcohol. See Capacitor Failure Symptoms for the general picture.

Apple's symptom charts work at module level. They send clicking, chirping or thumping, and a machine that does not power on, to the power supply and logic board, and a two-part error chord at start-up to the DRAM SIMMs and then the logic board.[5] Follow the charts before blaming the capacitors. On one Quadra 660AV that clicked every 5 to 10 seconds at power-on, cleaning the capacitor leakage off the logic board did not cure it; the click came from the speaker as the machine power-cycled, and a replacement power supply, the first cure in Apple's chart, did.[6] The Service Source has no capacitance, voltage-rating or designator data;[1] Apple's logic board schematic gives designators and values, listed below.

Logic board capacitors

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Quadra 660AV Recap Guide
Capacitor locations on the Centris / Quadra 660AV logic board, 820-0453-03 (Recap-a-Mac)

Recap-a-Mac's annotated map of a Quadra 660AV logic board (silk-screened 820-0453-03) marks thirteen surface-mount electrolytics:[2]

Centris / Quadra 660AV logic board electrolytics (Recap-a-Mac)[2]
Quantity Capacitance Voltage
11 47 µF 16 V
2 10 µF 16 V

Apple's logic board schematic, drawn for board 820-0453-B, has the same eleven 47 µF and two 10 µF polarised capacitors. It gives no voltage ratings; Recap-a-Mac and MacDat both read 16 V on every part.[2][4][7]

Centris / Quadra 660AV logic board electrolytics by designator (Apple schematic 051-0124-A)[7]
Designator Value Rail Sheet Notes
C3, C23, C27, C48, C52, C56 47 µF +5 V 29 Bulk bypass
C53 47 µF +5 V 28 At power connector J30
C55 47 µF +5 V 10 CIVIC video controller supply
C51 47 µF +12 V 28 At power connector J30
C50 47 µF −12 V 28 Positive terminal to ground
C21 47 µF −5 V 26 Serial driver supply; positive terminal to ground
C6 10 µF SCSI termination power 25 +5 V through diode D2 and fuse F5
C11 10 µF SCSI terminator output 25 Output of the MC34268 terminator regulator U8

Use the map to find each position and read the printing on each capacitor on your own board before ordering.

Replacements

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Recap-a-Mac fits KEMET solid tantalum capacitors: T491D476K016AT for the 47 µF 16 V positions and T491B106K016AT for the 10 µF 16 V positions.[2] Solid tantalums should be derated by 50 %: at least 10 V for a part on a 5 V rail and 25 V for one on 12 V. They usually fail short, so an under-rated tantalum can short a supply rail.[8] On this board C51 and C50 sit on the +12 V and −12 V rails, so a 16 V tantalum there runs at three-quarters of its rating; fit 25 V parts at those two positions.[7][8] Solid polymer electrolytics, or new surface-mount aluminium electrolytics of the same value and rating, are the alternatives.[8]

The polarity marking differs between types. On an aluminium electrolytic the stripe marks the negative terminal; on a tantalum the bar marks the positive terminal. A tantalum fitted with its bar where the old part's stripe was is reversed. C21 and C50 are on negative rails, so their positive terminals go to ground.[7]

Quadra 660AV Logic Board
Quadra 660AV logic board (Recap-a-Mac)

Replacement procedure

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  1. Work on an ESD mat with a wrist strap, with good light and magnification.
  2. Remove the logic board from the case.
  3. Photograph the board, including close-ups showing each capacitor's orientation.
  4. Remove the old capacitors with hot air, or by heating both terminations with the iron. Twisting or levering them off can lift the pads.
  5. Clean the area with isopropyl alcohol and a stiff brush, then inspect the pads and traces under magnification. Electrolyte left behind keeps corroding.
  6. Check continuity on the traces leading away from each position before fitting new parts.
  7. Fit the new capacitors with the polarity correct for their type: tin one pad, tack one end, solder the other, then reflow the first.
  8. Clean off the flux and inspect every joint.
  9. Test the board (power, video, keyboard) before reassembling the machine.

If leakage has broken traces, see Battery Explosion, Capacitor or Corrosion Damage. For tools see Recommended Tools.

Power supply

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The supply is Apple service part 661-1688, shared with the Centris 610,[9] which Apple's module identification manual lists as the 86 W supply with assembly number 614-0022 on its label.[10] Console5 identifies the Centris/Quadra 610 and 660AV supply as the ASTEC AA16990 (Apple 614-0022) and sells an electrolytic kit for it, asking buyers to open the supply and confirm the maker and revision first; the product page does not print the capacitor list.[11] Apple published no capacitor list for it; read the values off the parts in your own supply.

The supply's primary side runs at mains voltage and its reservoir capacitors hold a lethal charge after the machine is unplugged. Discharge each large capacitor through a resistor (1 kΩ, 5 W is suitable) and confirm with a meter before touching anything, and do not probe a powered primary side without an isolation transformer.

Apple's electrical specification is 100–240 V AC, 50–60 Hz, 86 W.[12] Low End Mac notes that the fan filter for this case is inside the supply, and that clearing dust from the mesh screen near the fan can revive a supply that appears dead.[13]

Battery

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Apple's check: set a voltmeter to the 10 V DC range, measure the battery (positive end marked "+" on the logic board), and replace it if it reads below 3.2 V.[14] A leaking battery damages the board in the same way as leaking capacitors. Check it whenever the machine is open.

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References

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  1. ↑ 1.0 1.1 Apple Computer, Centris 660AV/Quadra 660AV Service Source. Hosted as File:Quadra.centris_660av.pdf; see Centris 660AV/Quadra 660AV Service Source.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Macintosh Quadra 660AV, Recap-a-Mac—link(accessed 2026-09-30) Annotated logic board map "Quadra 660AV: 11 × 47µF 16V, 2 × 10µF 16V" (board 820-0453-03) and high-resolution PDF; replacements KEMET T491D476K016AT and T491B106K016AT. Secondary source.
  3. ↑ Recapping Service, Recap-a-Mac—link(accessed 2026-10-12) Source for ageing electrolytics leaking corrosive liquid that eats through traces, pads and the pins of other components, and for leaking capacitors having to be replaced before a machine can be restored.
  4. ↑ 4.0 4.1 Capacitor Reference - Macintosh Quadra 660av, MacDat—link(accessed 2026-10-12) Eleven 47 µF 16 V and two 10 µF 16 V surface-mount electrolytics, all listed for replacement. Secondary source.
  5. ↑ Centris 660AV/Quadra 660AV Service Source, Troubleshooting, Symptom Charts, Error Chords and System, pp. 2-4 (PDF pp. 20-22).
  6. ↑ Happy Macs, "A Quadra 660AV Revived", 23 October 2022. Secondary source: one owner's repair, in which cleaning capacitor leakage off the logic board did not stop the clicking and a replacement power supply did.
  7. ↑ 7.0 7.1 7.2 7.3 Apple Computer, The Tempest logic board schematic, drawing 051-0124-A, for board 820-0453-B: sheet 10 (C55 at the CIVIC video controller), sheet 25 (C6 and C11, SCSI termination), sheet 26 (C21 on the −5 V supply of the serial drivers), sheet 28 (C50, C51 and C53 at power connector J30) and sheet 29 (C3, C23, C27, C48, C52 and C56, "Bulk Bypass" on +5 V). The sheets give values but no voltage ratings. Hosted as File:Macintosh Quadra 660AV Schematic.pdf; see Macintosh Quadra 660AV Logic Board Schematic.
  8. ↑ 8.0 8.1 8.2 TinkerDifferent forum thread "Tantalum vs Electrolytic. Can I just always use tantalum?", January 2025. Secondary source for tantalum derating and failure mode; some members prefer solid polymer electrolytics.
  9. ↑ Centris 660AV/Quadra 660AV Service Source, Exploded View (PDF p. 97).
  10. ↑ Apple Computer, Module Identification, part number 072-8124, June 1994, p. 3.8.1 (PDF page 209): "Macintosh Power Supply, 86 Watt", Apple P/N 661-1688, with assembly number 614-0022 on the module label. Hosted as File:Apple Service Module Identification Manual (June 1994).pdf.
  11. ↑ Macintosh Centris / Quadra 610 / 660AV PSU Cap Kit - ASTEC AA16990, Console5—link(accessed 2026-09-30)
  12. ↑ Centris 660AV/Quadra 660AV Service Source, Specifications, Electrical, p. 11 (PDF p. 15).
  13. ↑ Centris 660av (Quadra 660av), Low End Mac—link(accessed 2026-09-30)
  14. ↑ Centris 660AV/Quadra 660AV Service Source, Additional Procedures, Battery Verification, p. 2 (PDF p. 92).


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