Jump to content

Macintosh LC II Capacitor Replacement Guide: Difference between revisions

From RetroTechCollection

Josh (talk | contribs)

5 user groups
13,142 edits
undo
VisualWikitext
Create Macintosh LC II capacitor guide
 
Copyedit; attribute the no-FPU-socket cost reason to Recap-a-Mac; add Recap-a-Mac KEMET parts and audio-socket warning; Performa relationship stated as Apple's manual gives it; cite chapters by page
 
(3 intermediate revisions by the same user not shown)
Line 1: Line 1:
Replacing the electrolytic capacitors (recapping) in the '''Macintosh LC II''' is essential for long-term reliability. The original capacitors used in these machines are now over 30 years old and commonly leak, causing corrosion and circuit damage.
<templatestyles src="Template:StyledTable/styles.css" />
[[File:Mac LC II Recap Guide.jpg|thumb|360px|Macintosh LC II logic board 820-0327 with the electrolytics marked (Recap-a-Mac)]]
The '''Macintosh LC II''' logic board, 820-0327-A, carries seventeen surface-mount electrolytic capacitors of 1991 vintage. They leak with age, and the electrolyte attacks the solder mask and the copper beneath it. 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 Recap-a-Mac's guide covers the LC II and Performa 400 together.<ref name="ss-p400">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.</ref><ref name="ram-lcii">{{cite web |url=https://recapamac.com.au/macintosh-lcii/ |title=Macintosh LC II (Performa 400) |publisher=Recap-a-Mac |access-date=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]]. Secondary source.</ref>


== Symptoms of Capacitor Failure ==
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]].


* '''No audio''' — Most common early symptom
== Signs of failure ==
* '''Distorted or crackling audio'''
* '''Boot failures or instability'''
* '''Visible electrolyte leakage''' — Brown or black residue around capacitors
* '''Corrosion on PCB traces'''


== Capacitor List ==
The pattern is the same as the rest of the family: residue around the capacitor bases, then faults in sound, startup or video. 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.<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. 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.</ref> See [[Macintosh LC Capacitor Replacement Guide]] and [[Capacitor Failure Symptoms]].


=== Logic Board Capacitors ===
== Macintosh LC II logic board (820-0327-A) ==


The Macintosh LC II logic board contains 17 surface-mount electrolytic capacitors, identical in specification to the original LC.
Seventeen surface-mount electrolytic capacitors. The per-designator list is Console5's; its totals by value (ten 10 µF, five 47 µF, one 100 µF and one 1 µF) match Recap-a-Mac's photograph of the same board.<ref name="console5-lc">{{cite web |url=https://wiki.console5.com/wiki/Macintosh_LC |title=Macintosh LC Series |publisher=Console5 TechWiki |access-date=2026-09-30}} Section "LC II Logic Board: 820-0327-A". Secondary source.</ref><ref name="ram-lcii" />


{| class="wikitable" style="width:80%; text-align:center;"
{| class="wikitable styled-table" style="width:70%; text-align:center;"
|+ '''Macintosh LC II Logic Board Capacitors'''
|+ '''Macintosh LC II logic board 820-0327-A, surface-mount electrolytics (Console5)'''
! Designator !! Value !! Voltage
|-
|-
! Designator !! Capacitance !! Voltage !! Type
| C11, C12, C14, C15, C16, C17, C18, C21, C97, C139 || 10 µF || 16 V
|-
|-
| C1 || 1 µF || 50V || SMD Electrolytic
| C2, C3, C4, C13, C19 || 47 µF || 16 V
|-
|-
| C2 || 1 µF || 50V || SMD Electrolytic
| C10 || 100 µF || 6.3 V
|-
|-
| C3 || 10 µF || 16V || SMD Electrolytic
| C22 || 1 µF || 50 V
|-
| C4 || 10 µF || 16V || SMD Electrolytic
|-
| C5 || 10 µF || 16V || SMD Electrolytic
|-
| C6 || 10 µF || 16V || SMD Electrolytic
|-
| C7 || 47 µF || 16V || SMD Electrolytic
|-
| C8 || 47 µF || 16V || SMD Electrolytic
|-
| C9 || 47 µF || 16V || SMD Electrolytic
|-
| C10 || 47 µF || 16V || SMD Electrolytic
|-
| C11 || 47 µF || 16V || SMD Electrolytic
|-
| C12 || 47 µF || 16V || SMD Electrolytic
|-
| C13 || 47 µF || 16V || SMD Electrolytic
|-
| C14 || 47 µF || 16V || SMD Electrolytic
|-
| C15 || 100 µF || 6.3V || SMD Electrolytic
|-
| C16 || 100 µF || 6.3V || SMD Electrolytic
|-
| C17 || 100 µF || 6.3V || SMD Electrolytic
|}
|}


=== Power Supply Capacitors ===
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.<ref name="console5-lc" /><ref name="ddb" />
 
The LC II uses the same power supply as the original LC. Refer to the [[Macintosh LC Power Supply Recap Guide]] for PSU-specific information.
 
== Capacitor Replacement Procedure ==


=== Tools Required ===
[[File:Mac LC II Recap Guide.jpg|center|thumb|700px|Macintosh LC II logic board 820-0327 with each electrolytic marked with its value, voltage and positive terminal. Source: Recap-a-Mac.]]


* Temperature-controlled soldering iron (recommended: 300-350°C)
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.<ref name="ram-lcii" />
* Fine tip for SMD work
* Desoldering braid or solder wick
* Flux (no-clean recommended)
* Isopropyl alcohol (99%)
* Soft brush (ESD-safe)
* Multimeter
* Replacement SMD electrolytic capacitors


=== Procedure ===
== Power supply, battery and procedure ==


# '''Remove the logic board''' — Disconnect all cables, remove screws, and carefully lift the board.
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 known makers' variants with different capacitor complements) and lithium battery 742-0011, which Apple says to replace below 3.0 V.<ref name="ss-lc">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.</ref><ref name="ss-p400" />
# '''Document capacitor positions''' — Note polarity markings before removal.
# '''Clean the area''' — Remove any leaked electrolyte with isopropyl alcohol.
# '''Remove old capacitors''' — Heat one pad while gently lifting the capacitor. Alternate between pads. Use flux to help solder flow.
# '''Clean the pads''' — Remove old solder with desoldering braid. Clean with IPA.
# '''Inspect for damage''' — Check traces and vias for corrosion. Repair any damaged traces.
# '''Install new capacitors''' — Observe polarity. The stripe on the capacitor indicates negative. Tin one pad, position capacitor, solder second pad, reflow first pad.
# '''Clean residue''' — Remove flux with isopropyl alcohol.
# '''Test continuity''' — Verify no shorts between +5V, +12V, and ground.
# '''Reassemble and test''' — Listen for the startup chime, verify video, and check audio output.


== Important Notes ==
== Things that are not faults ==


* '''Polarity matters''' — SMD electrolytics will fail if installed backwards.
* No FPU socket. Apple lists a coprocessor socket for the LC III and not for the LC II.<ref name="ss-lc" /> 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.<ref name="ram-lcii" /> Software that needs an FPU will not run.
* '''Use equivalent or better specs''' — Match capacitance; voltage rating can be equal or higher.
* A 10 MB RAM ceiling. The machine takes 12 MB but addresses 10 MB, which Apple documents.<ref name="ss-lc" />
* '''Low-ESR capacitors''' — Modern low-ESR replacements are acceptable.
* 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.<ref name="ss-lc" />
* '''No FPU socket''' — Note that the LC II does not have an FPU socket on the logic board, despite the 68030's FPU support.


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


* [[Macintosh LC II]]
* [[Macintosh LC II]]
* [[Macintosh LC II General Maintenance]]
* [[Macintosh LC II General Maintenance]]
* [[Macintosh LC II Troubleshooting]]
* [[Macintosh LC II Troubleshooting]]
* [[Macintosh LC Capacitor Replacement Guide]]
* [[Macintosh LC Series/ Quadra 605 Service Source]]


== External Resources ==
== References ==
 
<references />
* [https://recapamac.com.au/macintosh-lc-ii/ Recap-a-Mac: Macintosh LC II Capacitor Guide]


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

Latest revision as of 16:07, 30 September 2026

Macintosh LC II logic board 820-0327 with the electrolytics marked (Recap-a-Mac)

The Macintosh LC II logic board, 820-0327-A, carries seventeen surface-mount electrolytic capacitors of 1991 vintage. They leak with age, and the electrolyte attacks the solder mask and the copper beneath it. 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 Recap-a-Mac's guide covers the LC II and Performa 400 together.[1][2]

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]

The pattern is the same as the rest of the family: residue around the capacitor bases, then faults in sound, startup or video. 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.[3] 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; its totals by value (ten 10 µF, five 47 µF, one 100 µF and one 1 µF) match Recap-a-Mac's photograph of the same board.[4][2]

Macintosh LC II logic board 820-0327-A, surface-mount electrolytics (Console5)
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.[4][3]

Macintosh LC II logic board 820-0327 with each electrolytic marked with its value, voltage and positive terminal. Source: Recap-a-Mac.

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.[2]

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 known makers' 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. Apple lists a coprocessor socket for the LC III and not for the LC II.[5] 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.[2] 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.[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]
[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 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.
  2. ↑ 2.0 2.1 2.2 2.3 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. Secondary source.
  3. ↑ 3.0 3.1 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.
  4. ↑ 4.0 4.1 Macintosh LC Series, Console5 TechWiki—link(accessed 2026-09-30) Section "LC II Logic Board: 820-0327-A". Secondary source.
  5. ↑ 5.0 5.1 5.2 5.3 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.


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Macintosh_LC_II_Capacitor_Replacement_Guide&oldid=15957"