Macintosh LC III+ Capacitor Replacement Guide

The Macintosh LC III+ is a 33 MHz version of the LC III, sold to consumers as the Performa 460, 466 and 467. Its surface-mount electrolytic capacitors have the same thirty-year-old leakage problem as the rest of the family, and recapping it is essential maintenance.

Read your board number before you order parts. No capacitor list has ever been published for a board identified specifically as an LC III+ board, and this page does not invent one. What follows is what is actually documented, and how to work out which list applies to the machine in front of you.

What Apple documents

Apple services the LC III+ as part of the Performa 400 Series, alongside the Performa 400/405, 410, 430, 450 and 475/476.^[1] For the Performa 460/466/467 Apple specifies:

Item	Specification
Processor	Motorola 68030, 33 MHz, 32-bit internal data bus, burst-mode RAM access, coprocessor socket
DRAM	4 MB standard, expandable to 36 MB (80 ns or faster SIMMs)
ROM	1 MB
VRAM	512 K on board, upgradable to 768 K
Floppy drive	Apple SuperDrive, manual insert
Hard drive	80 MB (Performa 460); 160 MB (466/467)
Power supply	Apple 661-1733 — the same universal 100–240 VAC supply used by the whole LC pizza-box family
Battery	Apple 742-0011, 3.6 V lithium half-AA

All of the above comes from Apple's Performa 400 Series exploded view and specification chapters.^[1] Note what this tells you: the chassis, the power supply and the battery are common with the LC III, and the electrical specification of the LC III+ differs from the 25 MHz LC III only in clock speed.

Apple's separate Macintosh LC Series / Quadra 605 volume does not cover the LC III+ at all — it stops at the LC III and the LC 475.^[2] Neither volume contains component-level capacitor data for any model, so Apple is not the source for capacitor values on any of these machines.

What is not documented

Neither of the two community sources that carry per-designator capacitor lists for this family has an LC III+ entry:

Recap-a-Mac publishes an annotated photograph of an 820-0650-B board, captioned "Macintosh

 LC III (Performa 450)". It has no LC III+ page.^[3]

Console5 lists capacitors for boards 630-0309 (LC), 820-0327-A (LC II) and

 820-0650-A / 820-0650-B (LC III). It has no LC III+ entry.^[4]

Boards sold in the trade as Performa 460/466/467 or LC III+ boards are commonly marked 820-0650-B, the same number as the LC III board, but this wiki has not verified that on a bench and no published source states it as fact. Treat it as a strong expectation to be checked, not as a given.

The Macintosh LC III logic board, 820-0650-B, with each electrolytic marked. This is the LC III (Performa 450) board, photographed by Recap-a-Mac. If the board in your LC III+ carries the same 820-0650 number, this is your location map; if it does not, it is not. The circled part at the lower right is C22.

How to work out which list applies

Take the logic board out and read the number silk-screened in the top-left corner, beside the Apple copyright notice.
If it reads 820-0650 (any revision suffix), use the eleven-capacitor list on Macintosh LC III Capacitor Replacement Guide — including the C22 warning, which applies to that board and is the most important thing on this page.
If it reads anything else, do not assume. Photograph the board, read the value off each capacitor body before you remove it, and count what you find. A board that does not match 820-0650 is not covered by any published list, and this wiki would rather you measured than guessed.

C22

If your board is an 820-0650, one capacitor position — C22, the bulk capacitor on the −5 V rail — has both its factory placement and its PCB silkscreen reversed, and the replacement must go in the opposite way round to the silkscreen. This has been verified with a multimeter and cross-checked against the LC, LC II and LC 475 boards, which are wired correctly. Fitting a tantalum in the silk-screened orientation has been reported to pull the −5 V rail down to about −2.3 V with the capacitor drawing around 1.3 A.^[5] The full explanation, the circuit description and the continuity check you can run yourself are on Macintosh LC III Capacitor Replacement Guide.

Power supply, battery and procedure

Common to the whole family and documented on Macintosh LC Capacitor Replacement Guide: the shared Apple 661-1733 supply and its six known vendor variants, the removal and fitting procedure, and the 742-0011 lithium battery, which Apple says to replace below 3.0 V.^[2]^[1]

Related pages

Macintosh LC III+
Macintosh LC III Capacitor Replacement Guide — the list for the 820-0650 board
Macintosh LC III+ General Maintenance
Macintosh LC III+ Troubleshooting
Macintosh LC Capacitor Replacement Guide — shared procedure, power supply and battery
Macintosh Performa 400 Series Service Source

References

↑ ^1.0 ^1.1 ^1.2 Apple Computer, Service Source: Macintosh Performa 400 Series — covers the Performa 400/405, 410, 430, 450, 460/466/467 and 475/476. Hosted on this wiki as File:Performa 400 series.pdf; see Macintosh Performa 400 Series Service Source.
↑ ^2.0 ^2.1 Apple Computer, Service Source: Macintosh LC Series / Quadra 605 — Specifications, Troubleshooting, Take Apart, Additional Procedures and Exploded View chapters. Hosted on this wiki as File:Quadra 605.lc series.pdf; see Macintosh LC Series/ Quadra 605 Service Source.
↑ Recap-a-Mac — Macintosh LC III (Performa 450). Annotated photograph of the 820-0650-B logic board, and Recap-a-Mac's note that C22 on the −5 V rail was fitted the wrong way round. Hosted on this wiki as File:Mac LC III Recap Guide.jpg. Secondary source.
↑ Console5 Wiki — Macintosh LC. Community-maintained capacitor lists giving per-designator values for logic boards 630-0309 (LC), 820-0327-A (LC II) and 820-0650-A/B (LC III), and for six different LC-family power supplies. Secondary source: not an Apple document, but it agrees value-for-value with the independent Recap-a-Mac photographs.
↑ Doug Brown, “The capacitor that Apple soldered incorrectly at the factory”, 26 November 2024. Continuity and voltage measurements showing that C22 on the LC III board has its positive terminal on −5 V and its negative terminal on ground; comparison with the LC, LC II and LC 475 boards, which are wired the other way round; and the reported consequences of fitting a tantalum in the silkscreened orientation.

[ss-p400-1] 1.0 ^1.1 ^1.2 Apple Computer, Service Source: Macintosh Performa 400 Series — covers the Performa 400/405, 410, 430, 450, 460/466/467 and 475/476. Hosted on this wiki as File:Performa 400 series.pdf; see Macintosh Performa 400 Series Service Source.

[ss-lc-2] 2.0 ^2.1 Apple Computer, Service Source: Macintosh LC Series / Quadra 605 — Specifications, Troubleshooting, Take Apart, Additional Procedures and Exploded View chapters. Hosted on this wiki as File:Quadra 605.lc series.pdf; see Macintosh LC Series/ Quadra 605 Service Source.

[ram-lciii-3] Recap-a-Mac — Macintosh LC III (Performa 450). Annotated photograph of the 820-0650-B logic board, and Recap-a-Mac's note that C22 on the −5 V rail was fitted the wrong way round. Hosted on this wiki as File:Mac LC III Recap Guide.jpg. Secondary source.

[console5-lc-4] Console5 Wiki — Macintosh LC. Community-maintained capacitor lists giving per-designator values for logic boards 630-0309 (LC), 820-0327-A (LC II) and 820-0650-A/B (LC III), and for six different LC-family power supplies. Secondary source: not an Apple document, but it agrees value-for-value with the independent Recap-a-Mac photographs.

[ddb-5] Doug Brown, “The capacitor that Apple soldered incorrectly at the factory”, 26 November 2024. Continuity and voltage measurements showing that C22 on the LC III board has its positive terminal on −5 V and its negative terminal on ground; comparison with the LC, LC II and LC 475 boards, which are wired the other way round; and the reported consequences of fitting a tantalum in the silkscreened orientation.

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