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Twentieth Anniversary Macintosh Capacitor Replacement Guide

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Logic board 820-0816-D with its electrolytics circled: pink 47 µF 16 V, blue 100 µF 6.3 V, yellow 100 µF 25 V (C137). MacDat uses this map for the Power Macintosh 5500, 6500 and the TAM.

The Twentieth Anniversary Macintosh (TAM) has electrolytic capacitors on five assemblies: the logic board and the power distribution board in the main unit, the power supply board and the Bose amplifier board in the bass unit, and the CD-ROM drive. Apple's Service Source volume for the machine has no parts list, schematics or component values.[1] The values below come from two community lists, both secondary sources: MacDat's TAM page, compiled from information sent in by Daan, and a spreadsheet by the restorer iiiDIY that mac27.net hosts.[2][3] Where the two lists overlap they agree on every value, and the differences are noted below each table.

Restorers recap these machines as preventive work. In the mac27 restoration, Amiga of Rochester recapped all four boards, using polymer tantalum capacitors on the logic board, a mix of polymer and polymer tantalum on the power distribution board derated by about 20%, and aluminium electrolytics on the Bose amplifier board.[4][5] Restorers trace the "Bose buzz" to corroded spade connectors and pin headers in the bass unit; see the Twentieth Anniversary Macintosh Troubleshooting Guide.[6]

Logic board

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Logic board electrolytics (MacDat)
Position Value Voltage Size (diameter × height)
C34, C38, C48, C55, C66, C98, C104, C110, C125, C133, C134, C135 47 µF 16 V 6 × 5 mm
C24, C25, C36, C37, C39, C100 100 µF 6.3 V 6 × 5 mm
C137 100 µF 25 V 8 × 10 mm

All nineteen are surface-mount aluminium electrolytics.[2][7] iiiDIY's list has the same twelve 47 µF parts and C137, but only four 100 µF 6.3 V parts (C24, C25, C39 and C100); it omits C36 and C37, which sit beside C38 near the right-hand edge of the board in MacDat's photograph. iiiDIY gives the can size as 6.3 × 7 mm.[3] Measure the cans on your own board before ordering. The iFixit teardown photograph of a TAM shows C100 and C104 beside the PCI slot, where MacDat's map places them.[8]

Power distribution board

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J2 and J16, where the umbilical cable lands on the main unit board (Stephen Arsenault, CC BY 4.0)
Power distribution board electrolytics (iiiDIY)
Position Value Voltage Type and size
C1, C16, C19, C20 33 µF 25 V SMD, 6.3 × 7 mm
C2, C6, C21, C22 100 µF 6.3 V SMD, 6.3 × 7 mm
C7, C9 47 µF 16 V SMD, 6.3 × 7 mm
C4 10 µF 25 V SMD, 6.3 × 7 mm
C3, C23, C24, C26, C27 10 µF 16 V SMD, 4 mm
C30 0.47 µF 50 V SMD, 4 mm
Not given 10 µF 25 V Through-hole, short

iiiDIY lists C20 twice, in the 47 µF 16 V row and in the 33 µF 25 V row.[3] Stephen Arsenault's trace of the umbilical connections puts C1, C19 and C20 together on the +12 V line from pins 1 and 5 of J16, which matches the 33 µF 25 V row. The same trace has C2 on +5 V, C3 on the +5 V trickle line and C4 across −12 V, with C4's negative lead on −12 V and its positive lead on ground.[9] Fit C4 the same way round. iiiDIY gives no position for the through-hole 10 µF 25 V part; find it on the board before ordering.

Power supply board

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Power supply board from the bass unit, with positions numbered to match the table (MacDat)

Warning: this board runs from the mains. Positions 1 and 2 are the 200 V primary reservoir capacitors, and the board warns that heatsinks HS1 and HS2 are live. Unplug the bass unit, discharge both reservoir capacitors through a resistor and confirm with a meter before working on it. Check the 115/230 V switch before the first power-up.[2][10]

MacDat identifies the positions by numbers written on its photograph and suggests a replacement part for each; it gives no board designators for this board.[2]

Power supply board electrolytics (MacDat)
Photo no. Value Voltage Diameter Lead spacing MacDat replacement
1, 2 470 µF 200 V 22 mm 10 mm LGR2D471MELZ40
3, 12 1 µF 50 V 5 mm 2.5 mm ESH105M050AC3AA
4 2.2 µF 50 V 5 mm 2.5 mm UVY1H2R2MDD
5, 6, 10 47 µF 25 V 5 mm 2.5 mm ESW476M025AC3AA
7 100 µF 35 V 8 mm 5 mm ULD1V101MPD
8 47 µF 50 V 6.3 mm 2.5 mm UPM1H470MED1TD
9 100 µF 25 V 6.3 mm 2.5 mm EEU-FM1E101H
11 10 µF 50 V 5 mm 2.5 mm UPM1H100MDD1TA
13, 14 2200 µF 16 V 12 mm 5 mm UHV1C222MHD
15, 16 1000 µF 16 V 10 mm 5 mm UVZ1C102MPD1TD
17 470 µF 35 V 10 mm 5 mm EEU-FR1V471
18 470 µF 25 V 10 mm 5 mm EEU-FR1V471

MacDat gives the same 35 V Panasonic part for positions 17 and 18. Fuse F1 on this board is marked F6.3AH 250V.[2]

Bose amplifier board

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Bose amplifier board with its electrolytics colour-coded by value (MacDat)
Bose amplifier board electrolytics (MacDat)
Position Value Voltage Diameter MacDat replacement
C36 2200 µF 25 V 18 mm EEU-FC1E222S
C8 220 µF 16 V 10 mm EEU-FC1C221
C7, C9 100 µF 25 V 7 mm EEU-FM1E101H
C6, C23 47 µF 16 V 6.3 mm EEA-GA1C470B
C608, C708, C1021, C2021, C3021 22 µF 16 V 5 mm EEA-GA1C220B
C2, C15, C18, C21, C600, C605, C607, C609, C700, C705, C707, C709, C1002, C1004, C1020, C1903, C2002, C2004, C2903, C3020, C3250, C3903, C6903, C7903 10 µF 16 V 4.3 mm EEA-GA1C100B
C1200, C2200 1 µF 50 V 4.3 mm 860020672005

That is 37 positions.[2] The same board carries the two pin headers that restorers replace for the "Bose buzz", and a two-pin header marked TEST.[4][11]

CD-ROM drive

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CD-ROM drive electrolytics (iiiDIY)
Position Value Voltage Size
C100 330 µF 6.3 V 7 mm, short
C101 100 µF 16 V 7 mm, short
C21 100 µF 6.3 V 5 or 6 mm
C10 22 µF 6.3 V 4 mm
C39, C122, C123 10 µF 16 V 4 mm
C29 2.2 µF 25 V About 2 mm (uncertain in the list)
C14 1 µF 50 V 4 mm

All are through-hole parts. iiiDIY gives a quantity of two for the 10 µF 16 V row but names three positions, so count them on the drive.[3] The mac27 restoration left the CD-ROM drive alone; iiiDIY recapped theirs.[4]

Procedure

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  1. Take the boards out following the mac27.net guide: head unit steps 1–15 for the logic board and step 16 for the power distribution board, and base unit steps 1–9 for the Bose amplifier board and 10–12 for the power supply.[12] The plastics are brittle; read the cautions on the general maintenance page first.
  2. Photograph each board and note the polarity of every capacitor before removing anything.
  3. On the power supply board, discharge positions 1 and 2 and confirm with a meter.
  4. Remove the old capacitors and clean off any electrolyte residue. Capacitor Failure Symptoms shows what leakage looks like.
  5. Fit replacements of the same capacitance and the same or a higher voltage rating, matching the polarity you recorded. On the power distribution board, C4's positive lead goes to ground.[9]
  6. Check for solder bridges and shorts across each new part.
  7. Reassemble, set the voltage switch, and with the machine running measure +12 V on J16 pins 1 and 5 and +5 V on pins 2–4 against ground on pins 6–8.[9][10]
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References

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  1. ↑ Apple Computer, Twentieth Anniversary Macintosh Service Source (1997), Basics, "Overview", pp. 1–2 (PDF pp. 3–4), and contents: Basics, Specifications and the reproduced user manual only. File:Twentieth_anniversary_mac.pdf; see Twentieth Anniversary Macintosh Service Source.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 MacDat, Capacitor Reference Library, "Twentieth Anniversary Macintosh" (information sent in by Daan; read 2 October 2026): logic board map (shared with the Power Macintosh 5500 and 6500), power supply table numbered 1–18 against a board photograph, and Bose amplifier board table (secondary source).
  3. ↑ 3.0 3.1 3.2 3.3 iiiDIY, "TAM Capacitor List" (one-page PDF, April 2024), linked from mac27.net's restoration page: "Power Board", "Logic Board" and "CD ROM" tables giving size, voltage, capacitance, type, quantity and location (secondary source).
  4. ↑ 4.0 4.1 4.2 mac27.net, "Twentieth Anniversary Macintosh: 2023–'24 Restoration Project" (read 2 October 2026): recap of the motherboard, power distribution board, Bose amplifier board and power supply board by Thomas Andrews (Amiga of Rochester); capacitor types used; link to the iiiDIY list.
  5. ↑ Amiga of Rochester, "Twentieth Anniversary Macintosh Restoration" (10 February 2024).
  6. ↑ TinkerDifferent forum, "Fun with TAMs" (November 2024 – October 2025): buzz traced to spade connectors and amplifier board pin headers; wottle and dvsjr doubt that capacitors cause it.
  7. ↑ MacDat, Capacitor Reference Library, "Power Macintosh 6500" (read 2 October 2026): logic board 100 µF 25 V × 1 (8 × 10 mm), 100 µF 6.3 V × 6 and 47 µF 16 V × 12 (6 × 5 mm), all surface-mount electrolytic.
  8. ↑ iFixit, "Twentieth Anniversary Mac Teardown" (guide 12702, by Dylan, 2013), step 3 photograph.
  9. ↑ 9.0 9.1 9.2 Stephen Arsenault, "TAM-Umbilical" (GitHub, CC BY 4.0, read 2 October 2026): J16 pins 1 and 5 (+12 V) to C1(+), C19(+), C20(+); pins 2–4 (+5 V) to C2; J2 pin 2 (+5 V trickle) to C3(+); J2 pin 6 (−12 V) to C4, "the negative connector of C4 is −12V".
  10. ↑ 10.0 10.1 Apple Computer, Twentieth Anniversary Macintosh User Manual, reproduced in the Service Source (1997), Chapter 1, "Setting Up", p. 13 (PDF p. 36): voltage switch, "115" for 100–130 V and "230" for 200–270 V.
  11. ↑ TinkerDifferent forum, "Twentieth Anniversary Macintosh restoration follow-up and documentation of a minor fix inside the PSU (base unit)" (mac27, 1 December 2024): two-pin TEST header on the Bose amplifier board.
  12. ↑ mac27.net, "Twentieth Anniversary Macintosh: Comprehensive Disassembly Guide" (read 2 October 2026).
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