Macintosh LC 475 Capacitor Replacement Guide
The Macintosh LC 475 and the Macintosh Quadra 605 share one logic board, 820-0364-A (1993), which carries eleven surface-mount electrolytic capacitors.[1][2] Apple's Module Identification gives one service logic board, 661-1732, for the Quadra 605, LC 475, Macintosh Performa 475 and 476.[3][4] It is a different board from the Macintosh LC III, with a different capacitor complement. The general procedure, tools and power supply values for the family are on Macintosh LC Capacitor Replacement Guide.
Signs of failure
[edit | edit source]Quagmire Repair's dead 820-0364-A board, bought as already recapped, ran its fan and drives but gave no chime and no video. There was no voltage at C136, C137, C149 or C150, and leaked electrolyte had broken vias and a track under C136 and C137; the board chimed again once the vias were repaired.[5] Check the pads, tracks and vias around each position, on both sides of the board, as well as the capacitors themselves. For the battery and power supply checks to make first, see Macintosh LC Capacitor Replacement Guide and Capacitor Failure Symptoms.
The LC III has its −5 V filter capacitor fitted backwards at the factory, with the silkscreen printed the same wrong way. Doug Brown checked the LC 475 board and found it back in the correct orientation used on the LC and LC II, so the LC III warning does not apply here: fit each capacitor as marked.[6]
Logic board 820-0364-A
[edit | edit source]| Value | Voltage | Quantity | Type |
|---|---|---|---|
| 47 µF | 16 V | 9 | Surface-mount |
| 100 µF | 6.3 V | 2 | Surface-mount |
The values are from Recap-a-Mac's annotated photograph, which also serves as the location map, and MacDat's list gives the same eleven parts.[1][7] Apple's Service Source gives no component values for it.[2] The two 100 µF parts are C136 and C137, at the top left corner of the board; C149 and C150 are two of the 47 µF parts beside them. Read the value on each capacitor before removing it.
Recap-a-Mac replaces them with KEMET tantalums of the same value and voltage (T491D476K016AT and T491D107K006AT).[1]
Power supply
[edit | edit source]Recap-a-Mac treats the LC, LC II, LC III, LC 475 and Quadra 605 supplies as one design, prone to leakage and failures in its smaller capacitors, and publishes one recapping guide for all of them.[8] Apple's exploded view for the family gives the supply as 661-1733.[2] MacDat lists three makers of the LC 475 supply, TDK, Astec (in at least two versions, AA16251 and AA19140) and Dyna Comp, each with a different capacitor complement; it singles out the TDK unit, whose ELNA LongLife capacitors leak worst. The primary bulk capacitor is 180 µF, rated 385 V on the TDK and 400 V on the Astec and Dyna Comp units. Identify the maker from the label before ordering parts.[7] The per-maker values are on MacDat and Macintosh LC Capacitor Replacement Guide. The supply works from mains voltage and its primary capacitors hold a charge after it is unplugged.
Battery
[edit | edit source]Apple's part is lithium battery 742-0011, a ½AA cell in a clip-in holder; EveryMac gives it as 3.6 V.[2][1][9] Apple's check is to measure it on the 10 V DC range and replace it below 3.0 V.[2] Recap-a-Mac fitted a CR2032 holder in place of the original on the board in its photograph.[1] A CR2032 is a nominal 3 V cell, the same as Apple's replace-below figure. See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.
Around the processor
[edit | edit source]The 68LC040 is in a socket.[2] Apple removes it only with a processor removal tool (a separate service part), lifting the tool's handle up (pressing down can damage parts on the logic board) and prying each side up only slightly so that the pins do not bend.[2] The EMI clips on the underside of the LC 475 and Quadra 605 boards flex easily, and Apple warns against heavy pressure on them or on the board.[2]
When a replacement board goes in, the grounding pad or spring on the audio ports moves across from the old board, and a Quadra 605 needs the J18 jumper fitted.[2]
Related pages
[edit | edit source]- Macintosh LC 475
- Macintosh Quadra 605
- Macintosh LC 475 General Maintenance
- Macintosh LC 475 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 LC475 & Quadra 605, Recap-a-Mac—link(accessed 2026-09-30) Annotated photograph of logic board 820-0364-A, hosted here as File:Mac LC 475 Recap Guide.jpg, with each capacitor's value, voltage and positive terminal marked; replacement parts KEMET T491D476K016AT (47 µF 16 V) and T491D107K006AT (100 µF 6.3 V) tantalums; the author replaced the ½AA battery holder with a CR2032 holder. A secondary source.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Apple Computer, Macintosh LC Series/Quadra 605 Service Source (1995), File:Quadra_605.lc_series.pdf; see Macintosh LC Series/ Quadra 605 Service Source. PDF page numbers: Specifications pp. 6-17; Take Apart, Logic Board pp. 55-63 (J18 jumper and grounding connectors pp. 60-63); Macintosh Processor Upgrade pp. 87-104 (processor removal cautions p. 94); Battery Verification p. 107; Battery Replacement pp. 108-110; Exploded View p. 112.
- ↑ Apple Computer, Module Identification, part number 072-8124, June 1994, section 1.5.11 (PDF p. 85): "Macintosh Quadra 605, LC 475, Performa 475, 476 Logic Board", Apple P/N 661-1732. Hosted as File:Apple Service Module Identification Manual (June 1994).pdf.
- ↑ Apple Computer, Macintosh Performa 400 Series Service Source, File:Performa 400 series.pdf; see Macintosh Performa 400 Series Service Source. Covers the Performa 400/405, 410, 430, 450, 460/466/467 and 475/476.
- ↑ Quadra 605/LC 475, Quagmire Repair, 2021-07-09—link(accessed 2026-10-12) Repair log of a dead, already recapped 820-0364-A board: fan and drives run, no chime or video; no voltage at C136, C137, C149 and C150; vias and a track under C136 and C137 damaged by leaked electrolyte; the board chimed after the vias were repaired.
- ↑ Doug Brown, "The capacitor that Apple soldered incorrectly at the factory", 26 November 2024. C22 on the LC III board has its positive terminal on −5 V; the LC, LC II and LC 475 boards have the correct orientation.
- ↑ 7.0 7.1 Macintosh LC 475 Capacitor Reference, MacDat—link(accessed 2026-09-30) Logic board 2 × 100 µF 6.3 V and 9 × 47 µF 16 V; power supply lists for TDK, Astec AA16251, Astec AA19140 and Dyna Comp. A secondary source.
- ↑ Macintosh LC Power Supply (For LC, LC II, LC III, LC 475 and Quadra 605), Recap-a-Mac—link(accessed 2026-09-30)
- ↑ Apple Macintosh LC 475 Specs, EveryMac—link(accessed 2026-09-30) Battery type 3.6 V lithium.