Macintosh LC II Capacitor Replacement Guide
The Macintosh LC II logic board, 820-0327-A, carries seventeen surface-mount electrolytic capacitors of 1991 vintage, all of which Recap-a-Mac says need replacing.[1] Leaked electrolyte from this family's capacitors attacks the solder mask and the copper beneath it; Doug Brown found both damaged on a Performa 450 board.[2] The board is different from the original LC's, with a different capacitor complement. Apple's Performa 400 series manual gives the Performa 400, 405, 410 and 430 the LC II's processor, memory and expansion specifications, and Apple's Module Identification lists one 4 MB service logic board, 661-0729, for the LC II and Performa 400, 405, 410 and 430.[3] Recap-a-Mac's guide covers the LC II and Performa 400 together.[4][1]
The tools, the removal and fitting procedure, the power supply lists and the battery are common to the LC family and are on Macintosh LC Capacitor Replacement Guide.
Signs of failure
[edit | edit source]Look for residue around the capacitor bases and on the pads, and check the PRAM battery and the power supply before blaming the board; Macintosh LC Capacitor Replacement Guide gives the checks. The −5 V rail on these boards is needed only for the RS-422 serial ports, so a bad bulk capacitor on it shows up as serial port trouble.[2] See Macintosh LC Capacitor Replacement Guide and Capacitor Failure Symptoms.
Macintosh LC II logic board (820-0327-A)
[edit | edit source]Seventeen surface-mount electrolytic capacitors. The per-designator list is Console5's, a community list read from boards. Its totals by value (ten 10 µF, five 47 µF, one 100 µF and one 1 µF) match Recap-a-Mac's annotated photograph of the same board, and its designators match the silkscreen in Recap-a-Mac's unannotated photograph of a recapped 820-0327-A board.[5][1]
| Designator | Value | Voltage |
|---|---|---|
| C11, C12, C14, C15, C16, C17, C18, C21, C97, C139 | 10 µF | 16 V |
| C2, C3, C4, C13, C19 | 47 µF | 16 V |
| C10 | 100 µF | 6.3 V |
| C22 | 1 µF | 50 V |
The LC III has a reversed capacitor at C22. The LC II's C22 is a different part, a 1 µF 50 V capacitor in a different place, and nothing is wrong with it; Doug Brown found the −5 V bulk capacitor on the LC and LC II wired the correct way round.[5][2]
Recap-a-Mac lists KEMET tantalum replacements: T491B105K050AT (1 µF 50 V), T491D476K016AT (47 µF 16 V), T491D107K006AT (100 µF 6.3 V) and T491B106K016AT (10 µF 16 V). It also warns that the plastic audio sockets melt easily.[1]
Power supply, battery and procedure
[edit | edit source]These are the same as the rest of the family and are on Macintosh LC Capacitor Replacement Guide: power supply 661-1733 (100–240 V AC, six variants from three makers, with different capacitor complements) and lithium battery 742-0011, which Apple says to replace below 3.0 V.[6][4]
Things that are not faults
[edit | edit source]- No FPU socket. Apple lists a coprocessor socket for the LC III and not for the LC II.[6] Recap-a-Mac says the LC II board was designed so that an FPU could be fitted but Apple left the socket off to save cost.[1] Software that needs an FPU will not run.
- A 10 MB RAM ceiling. The machine takes 12 MB but addresses 10 MB, which Apple documents.[6]
- Mono sound. Apple's specification for the LC, LC II and LC III is a monophonic 8-bit sound generator feeding the same signal to both channels.[6]
Related pages
[edit | edit source]- Macintosh LC II
- Macintosh LC II General Maintenance
- Macintosh LC II Troubleshooting
- Macintosh LC Capacitor Replacement Guide
- Macintosh LC Series/ Quadra 605 Service Source
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Macintosh LC II (Performa 400), Recap-a-Mac—link(accessed 2026-09-30) Annotated photograph of logic board 820-0327 (c) 1991, legend 1 × 1 µF 50 V, 10 × 10 µF 16 V, 5 × 47 µF 16 V, 1 × 100 µF 6.3 V; KEMET replacements T491B105K050AT, T491D476K016AT, T491D107K006AT and T491B106K016AT; warning that the plastic audio sockets melt easily; note that Apple left the FPU socket off to save cost. Hosted here as File:Mac LC II Recap Guide.jpg. The page's second, unannotated photograph shows the recapped board with its silkscreen legible: 820-0327-A, and C2, C3, C4, C13 and C19 at the 47 µF positions, C10 at the 100 µF, C22 at the 1 µF. Secondary source.
- ↑ 2.0 2.1 2.2 Doug Brown, "The capacitor that Apple soldered incorrectly at the factory", 26 November 2024. C22 on the LC III board is reversed; the LC and LC II boards are wired correctly; the −5 V rail is only needed for the RS-422 serial ports; C21 on a Performa 450 board had leaked and damaged the solder mask and the copper beneath it.
- ↑ Apple Computer, Module Identification, part number 072-8124, June 1994, section 1.11.3 (PDF p. 113): "Macintosh LC II, Performa 400/405/410/430 Logic Board, 4 MB", Apple P/N 661-0729. Hosted as File:Apple Service Module Identification Manual (June 1994).pdf.
- ↑ 4.0 4.1 Apple Computer, Macintosh Performa 400 Series Service Source, covering the Performa 400/405, 410, 430, 450, 460/466/467 and 475/476, File:Performa 400 series.pdf (see Macintosh Performa 400 Series Service Source), Specifications, PDF pp. 3-10.
- ↑ 5.0 5.1 Macintosh LC Series, Console5 TechWiki—link(accessed 2026-09-30) Section "LC II Logic Board: 820-0327-A". Secondary source.
- ↑ 6.0 6.1 6.2 6.3 Apple Computer, Macintosh LC Series/Quadra 605 Service Source, File:Quadra 605.lc series.pdf (see Macintosh LC Series/ Quadra 605 Service Source): Specifications, PDF pp. 6-17; symptom charts, PDF p. 36; Battery Verification, PDF p. 107; Exploded View, PDF p. 112.