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Macintosh LC III+ Capacitor Replacement Guide: Difference between revisions

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Add the 820-0650-B location photograph, captioned to make clear it is the LC III board and applies only if your LC III+ board carries the same number
 
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{{Unverified data}}
The '''Macintosh LC III+''' is a 33 MHz version of the
Replacing the electrolytic capacitors (recapping) in the '''Macintosh LC III+''' is essential for long-term reliability.
[[Macintosh LC III|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.


== Known Factory Defect: C22 ==
'''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.


'''Important:''' Like the LC III, the Macintosh LC III+ has a known manufacturing defect where '''capacitor C22 was installed with reversed polarity''' at the factory. The silkscreen marking on the PCB is printed backwards.
== What Apple documents ==


When replacing capacitors, install C22 with '''correct polarity''' according to the capacitor's markings, '''not''' the PCB silkscreen.
Apple services the LC III+ as part of the Performa 400 Series, alongside the Performa 400/405, 410, 430,
450 and 475/476.<ref name="ss-p400">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]].</ref> For the Performa 460/466/467 Apple specifies:


== Symptoms of Capacitor Failure ==
<templatestyles src="Template:StyledTable/styles.css" />
 
{| class="wikitable styled-table" style="width:80%;"
* '''No audio''' — Most common early symptom
! Item !! Specification
* '''Distorted or crackling audio'''
* '''Boot failures or instability'''
* '''Visible electrolyte leakage''' — Brown or black residue around capacitors
* '''Corrosion on PCB traces'''
 
== Capacitor List ==
 
=== Logic Board Capacitors ===
 
The LC III+ uses the same capacitor layout as the LC III.
 
{| class="wikitable" style="width:80%; text-align:center;"
|+ '''Macintosh LC III+ Logic Board Capacitors'''
|-
! Designator !! Capacitance !! Voltage !! Notes
|-
|-
| C1 || 1 µF || 50V ||
| Processor || Motorola 68030, 33 MHz, 32-bit internal data bus, burst-mode RAM access, coprocessor socket
|-
|-
| C2 || 1 µF || 50V ||
| DRAM || 4 MB standard, expandable to 36 MB (80 ns or faster SIMMs)
|-
|-
| C3 || 10 µF || 16V ||
| ROM || 1 MB
|-
|-
| C4 || 10 µF || 16V ||
| VRAM || 512 K on board, upgradable to 768 K
|-
|-
| C5 || 10 µF || 16V ||
| Floppy drive || Apple SuperDrive, manual insert
|-
|-
| C6 || 10 µF || 16V ||
| Hard drive || 80 MB (Performa 460); 160 MB (466/467)
|-
|-
| C7 || 47 µF || 16V ||
| Power supply || Apple 661-1733 — the same universal 100–240 VAC supply used by the whole LC pizza-box family
|-
|-
| C8 || 47 µF || 16V ||
| Battery || Apple 742-0011, 3.6 V lithium half-AA
|-
| C9 || 47 µF || 16V ||
|-
| C10 || 47 µF || 16V ||
|-
| C11 || 47 µF || 16V ||
|-
| C12 || 47 µF || 16V ||
|-
| C13 || 47 µF || 16V ||
|-
| C14 || 47 µF || 16V ||
|-
| C15 || 100 µF || 6.3V ||
|-
| C16 || 100 µF || 6.3V ||
|-
| C17 || 100 µF || 6.3V ||
|-
| C22 || 47 µF || 16V || '''Factory reversed polarity — install correctly!'''
|}
|}


[[File:Mac LC III Recap Guide.jpg|center|thumb|600px|Macintosh LC III/III+ logic board capacitor locations. Note C22 silkscreen error. Source: [https://recapamac.com.au/macintosh-lciii/ Recap-a-Mac]]]
All of the above comes from Apple's Performa 400 Series exploded view and specification
chapters.<ref name="ss-p400" /> 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.<ref name="ss-lc">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]].</ref> 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 ==


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


Refer to the [[Macintosh LC Power Supply Recap Guide]] for PSU-specific information.
* '''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.<ref name="ram-lciii">[https://recapamac.com.au/macintosh-lciii/ 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.</ref>
* '''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.<ref name="console5-lc">[https://wiki.console5.com/wiki/Macintosh_LC 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.</ref>


[[File:Mac LC PSU Recap Guide.jpg|center|thumb|600px|Macintosh LC power supply capacitor locations. Source: [https://recapamac.com.au/macintosh-lc-power-supply/ Recap-a-Mac]]]
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.


== Capacitor Replacement Procedure ==
[[File:Mac LC III Recap Guide.jpg|center|thumb|700px|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.]]


=== Tools Required ===
== How to work out which list applies ==


* Temperature-controlled soldering iron (recommended: 300-350°C)
# Take the logic board out and read the number silk-screened in the top-left corner, beside the Apple copyright notice.
* Fine tip for SMD work
# '''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.
* Desoldering braid or solder wick
# '''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.
* Flux (no-clean recommended)
* Isopropyl alcohol (99%)
* Soft brush (ESD-safe)
* Multimeter
* Replacement SMD electrolytic capacitors


=== Procedure ===
== C22 ==


# '''Remove the logic board''' — Disconnect all cables, remove screws, and carefully lift the board.
If your board is an 820-0650, one capacitor position — '''C22''', the bulk capacitor on the
# '''Document capacitor positions''' — Note polarity markings before removal.
−5 V rail — has both its factory placement and its PCB silkscreen reversed, and the
# '''Clean the area''' — Remove any leaked electrolyte with isopropyl alcohol.
replacement must go in the opposite way round to the silkscreen. This has been verified with a multimeter
# '''Remove old capacitors''' — Heat one pad while gently lifting the capacitor. Alternate between pads.
and cross-checked against the LC, LC II and LC 475 boards, which are wired correctly. Fitting a tantalum
# '''Clean the pads''' — Remove old solder with desoldering braid. Clean with IPA.
in the silk-screened orientation has been reported to pull the −5 V rail down to about
# '''Inspect for damage''' — Check traces and vias for corrosion.
−2.3 V with the capacitor drawing around 1.3 A.<ref name="ddb">Doug Brown, [https://www.downtowndougbrown.com/2024/11/the-capacitor-that-apple-soldered-incorrectly-at-the-factory/ “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.</ref> The full explanation, the circuit
# '''Install new capacitors''' — Observe polarity. '''For C22: ignore the PCB silkscreen.'''
description and the continuity check you can run yourself are on
# '''Clean residue''' — Remove flux with isopropyl alcohol.
[[Macintosh LC III Capacitor Replacement Guide]].
# '''Test continuity''' — Verify no shorts between +5V, +12V, and ground.
# '''Reassemble and test'''


== Important Notes ==
== Power supply, battery and procedure ==


* '''C22 silkscreen error''' — The PCB marking is wrong. Install based on the capacitor's polarity marking.
Common to the whole family and documented on [[Macintosh LC Capacitor Replacement Guide]]: the shared
* '''Polarity matters''' — SMD electrolytics will fail if installed backwards.
Apple 661-1733 supply and its six known vendor variants, the removal and fitting procedure, and the
* '''Use equivalent or better specs''' — Match capacitance; voltage rating can be equal or higher.
742-0011 lithium battery, which Apple says to replace below 3.0 V.<ref name="ss-lc" /><ref name="ss-p400" />


== Related Pages ==
== Related pages ==


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


== External Resources ==
== References ==
 
<references />
* [https://recapamac.com.au/macintosh-lciii/ Recap-a-Mac: Macintosh LC III Capacitor Guide] (same board as LC III)


[[Category:Apple Vintage Computers]]
[[Category:Apple Vintage Computers]]
[[Category: Capacitor Replacement Guides]]
[[Category:Capacitor Replacement Guides]]
{{Navbox-AppleVintage|state=collapsed}}
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