Macintosh LC II Capacitor Replacement Guide
Replacing the surface-mount electrolytic capacitors in the Macintosh LC II is essential maintenance. The 1991-vintage SMD electrolytics leak, and the electrolyte attacks the solder mask and the copper beneath it.
The LC II logic board is 820-0327-A, a different board from the original LC with a different capacitor complement, so the two lists are not interchangeable. The same board is used by the Performa 400, 405, 410 and 430.[1]
The tools, the removal and fitting procedure, the power supply data and the battery information are common to the whole "pizza box" family and are documented once, on the Macintosh LC Capacitor Replacement Guide. This page carries only what is specific to the LC II.
Symptoms of capacitor failure
[edit | edit source]The pattern is the same as the rest of the family: sound goes first, then intermittent starting, then visible residue and corroded copper. Because the −5 V rail on these boards exists mainly to feed the RS-422 serial drivers, a failed bulk capacitor on that rail tends to show up as modem and printer port trouble on its own.[2] See Macintosh LC Capacitor Replacement Guide for the full symptom list, and Capacitor Failure Symptoms for the general picture.
Macintosh LC II logic board (820-0327-A)
[edit | edit source]Seventeen surface-mount electrolytic capacitors. The per-designator list is Console5's; the totals by value — ten 10 µF, five 47 µF, one 100 µF and one 1 µF — match the independently produced Recap-a-Mac photograph of the same board exactly.[3][4]
| Designator | Value | Working 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 |
Note on C22. The LC III has a well-known reversed capacitor at C22. The LC II also has a C22, but it is a different part in a different place — a 1 µF 50 V — and there is nothing wrong with it. The LC and LC II bulk capacitors on the −5 V rail are wired the correct way round; only the LC III board is affected.[2]
Power supply, battery and procedure
[edit | edit source]Identical to the rest of the family, and documented on Macintosh LC Capacitor Replacement Guide: Apple power supply 661-1733 (universal 100–240 VAC, six known vendor variants with different capacitor complements) and lithium battery 742-0011, which Apple says to replace below 3.0 V.[5][1]
Things that are not faults
[edit | edit source]- No FPU socket. The LC II uses a 68030, which has no on-chip FPU, and Apple did not fit a
coprocessor socket to this board — the socket first appears on the LC III.[5] Software that demands an FPU will not run, and that is not a capacitor problem.
- 10 MB RAM ceiling. You can install 12 MB but the machine only addresses 10 MB. Apple
documents this explicitly.[5]
- 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.[5]
Related pages
[edit | edit source]- Macintosh LC II
- Macintosh LC II General Maintenance
- Macintosh LC II Troubleshooting
- Macintosh LC Capacitor Replacement Guide — shared procedure, power supply and battery
- Macintosh LC Series/ Quadra 605 Service Source
References
[edit | edit source]- ↑ 1.0 1.1 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 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.
- ↑ 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.
- ↑ Recap-a-Mac — Macintosh LC II (Performa 400). Annotated photograph of the 820-0327 logic board. Hosted on this wiki as File:Mac LC II Recap Guide.jpg. Secondary source.
- ↑ 5.0 5.1 5.2 5.3 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.