Editing Macintosh Quadra 605 Capacitor Replacement Guide

Recapping the '''[[Macintosh Quadra 605]]''' is straightforward by the standards of this family: eleven surface-mount electrolytics, all on the top side of the board, and no silkscreen traps.

The logic board is '''820-0364-A''' (1993). It is the same board as the [[Macintosh LC 475]] and the [[Macintosh Performa 475]]/476, so this page and [[Macintosh LC 475 Capacitor Replacement Guide]] describe one board under two names; the LC 475 page carries the annotated board photograph and this one carries the working detail. Tools, removal and fitting procedure, power-supply data and battery information are common to the whole "pizza box" family and live on [[Macintosh LC Capacitor Replacement Guide]].<ref name="ss-lcser">Apple Computer, ''Service Source: Macintosh LC Series / Quadra 605''. Hosted on this wiki as [[:File:Quadra 605.lc series.pdf]]; see [[Macintosh LC Series/ Quadra 605 Service Source]]. Chapters used: Specifications (Processor, Memory, I/O Interfaces, Sound and Video, Electrical, Physical), Troubleshooting (Symptom Charts), Take Apart, Additional Procedures (Battery Verification) and Exploded View.</ref>

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== The logic board: 820-0364-A ==

'''Eleven surface-mount electrolytic capacitors:'''

{| class="wikitable styled-table" style="width:70%; text-align:center;"
|+ Macintosh Quadra 605 / LC 475 logic board 820-0364-A
! Value !! Working voltage !! Quantity
|-
| 47 µF || 16 V || 9
|-
| 100 µF || 6.3 V || 2
|}

Two independent community sources give exactly that complement: MacDat's reference list, and Recap-a-Mac's annotated photograph of an 820-0364-A board.<ref name="macdat">MacDat Capacitor Reference Library, Apple section — https://macdat.net/repair/cap_reference/apple/ . Secondary source: a community-maintained capacitor reference compiled from physical boards, giving value-and-count lists and, for most boards, an annotated reference photograph. Used here for the per-board electrolytic complements quoted, which agree with Recap-a-Mac’s independently produced board photographs wherever both cover the same board.</ref><ref name="ram475">Recap-a-Mac, ’’Macintosh LC 475 / Quadra 605’’ — https://recapamac.com.au/macintosh-lc475/ . Annotated photograph of the 820-0364-A logic board with every electrolytic marked with its value, working voltage and positive terminal. Hosted on this wiki as [[:File:Mac LC 475 Recap Guide.jpg]]. Secondary source: one repairer’s reading of boards handled personally.</ref>

'''There are no 10&nbsp;µF parts on this board.''' Lists that put four 10&nbsp;µF capacitors on a Quadra&nbsp;605 have been copied from another machine — probably one of the earlier LC boards, which do carry them. If you buy a kit containing 10&nbsp;µF parts for this board, you have the wrong kit.

Equally, '''there is no "various" row.''' Every electrolytic on this board is one of the two values above.

[[File:Mac LC 475 Recap Guide.jpg|center|thumb|700px|Macintosh LC 475 / Quadra 605 logic board 820-0364-A. Each capacitor is marked with its value, working voltage and positive terminal. Source: Recap-a-Mac.]]

=== How solid are these numbers ===

Apple never published component-level capacitor data for any Macintosh of this era, so both sources here are secondary: MacDat's list and Recap-a-Mac's photograph are each one careful reader's record of physical boards. They were produced independently and they agree, which is about as good as corroboration gets for this machine. Console5 does not carry an 820-0364 entry at all.

The photograph is therefore both the value list and the location map. '''Work from it rather than from a designator table, and read the value printed on each can before you lift it.'''

=== The −5 V bulk capacitor is the right way round here ===

The [[Macintosh LC III]] has a notorious factory error: its bulk capacitor on the −5&nbsp;V rail is both placed and silk-screened backwards. '''The 820-0364 board is not affected.''' If a recapped LC&nbsp;475 or Quadra&nbsp;605 has serial-port faults, that is a genuine fault to chase rather than the LC&nbsp;III's known error.

== What failure looks like ==

The same family pattern as the rest of the LC boards, generally less far advanced because these boards are two to three years younger and use fewer, larger capacitors:

* '''Sound first.''' Weak, crackling or absent audio is usually the earliest symptom, because the audio section is decoupled by several of these parts.
* '''Then intermittent starting''' — a chime that needs two attempts, or a machine that only starts when cold.
* '''Then visible residue''': brown or amber staining around a capacitor base, dull or crazed solder mask nearby, green or white crystalline deposits where electrolyte has reached copper.

A capacitor does not have to look swollen to have failed. On small surface-mount parts the usual failure is a seeped seal, not a bulged can, and the evidence hides underneath the body until the can comes off. See [[Capacitor Failure Symptoms]].

'''A board that is two to three years younger is not a board that does not need doing.''' An unrecapped 820-0364 in 2026 still needs doing.

== Replacement ==

The full procedure — tools, removal technique, pad cleaning, trace checking and fitting — is on [[Macintosh LC Capacitor Replacement Guide]] and is not repeated here. Three points are specific to this board:

# '''Photograph the board first''', at enough resolution to read the silkscreen and see the polarity mark on every can. That photograph is your record of which way round each part went.
# '''Check polarity against your photographs, not against memory.''' On an aluminium surface-mount electrolytic the stripe marks the '''negative''' terminal. If you substitute tantalums, the bar marks the '''positive''' end — the opposite convention, and the commonest way to destroy a freshly recapped board.
# '''Buzz out every track that runs away from a capacitor pad''' after removal. Corrosion under the solder mask does not show from above, and a track that measures open has to be jumpered before the board will work.

=== On solder and temperature ===

These boards were assembled with '''leaded''' solder. Use leaded solder to repair them and work at a temperature that suits it — around 315–340&nbsp;°C on a fine tip for surface-mount work is plenty. The 350–380&nbsp;°C sometimes quoted is lead-free advice and it lifts pads on thirty-year-old boards.

If you use hot air, shield adjacent plastic connectors and the SIMM sockets. They soften long before the solder flows.

=== Tantalum substitutes ===

Tantalums are a common and long-lived substitute here and they cannot leak. Two things to know:

* They '''fail short''', not open, so a reversed or under-rated part pulls its rail down instead of quietly losing capacitance.
* Derate them. A solid tantalum wants roughly twice the working voltage of the rail it sits on, so a part on a 5&nbsp;V rail should be rated 10&nbsp;V or more. The 16&nbsp;V and 6.3&nbsp;V ratings above are the ''original'' aluminium parts' ratings; matching or exceeding them is the minimum, not the target.

Polymer aluminium parts are a reasonable middle ground: they do not leak and they fail benignly rather than shorting.

== The power supply ==

Shared with the whole family: Apple part '''661-1733''', a universal auto-ranging switch-mode unit for 100–240&nbsp;VAC.<ref name="ss-lcser" /> Apple bought it from several vendors and the capacitor complements differ between them, so read the maker's label before ordering. The per-variant lists, and the annotated photograph of the TDK-built unit, are on [[Macintosh LC Capacitor Replacement Guide]].

'''Apple documents no voltage adjustment and no rail tolerance for this machine.''' There is no trimmer to set and no acceptable-range table in the ''Service Source''; every power fault in Apple's symptom charts ends in "Replace power supply".<ref name="ss-lcser" /> Tables of "expected voltages" for the Quadra&nbsp;605 that circulate online are not Apple's and are not reproduced here.

== Battery ==

A '''3.6&nbsp;V lithium half-AA''', Apple part '''742-0011''', in a clip-in holder. Apple's check: measure it on the 10&nbsp;V DC range and '''replace it if it reads below 3.0&nbsp;V'''.<ref name="ss-lcser" /> Replace it while the board is out and the area is clean.

If it has already leaked, neutralise with '''bicarbonate of soda''', not vinegar — this is a lithium cell, and vinegar is the treatment for alkaline leakage. See [[Battery Explosion, Capacitor or Corrosion Damage]] and [[Macintosh Quadra 605 General Maintenance]].

== Related pages ==

* [[Macintosh Quadra 605]]
* [[Macintosh Quadra 605 General Maintenance]]
* [[Macintosh Quadra 605 Troubleshooting]]
* [[Macintosh LC 475 Capacitor Replacement Guide]] — the same board, with the source photograph
* [[Macintosh LC Capacitor Replacement Guide]] — shared procedure, power supply and battery
* [[Macintosh LC Series/ Quadra 605 Service Source]]
* [[Capacitor Failure Symptoms]]
* [[Recommended Tools]]

== References ==
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[[Category:Apple Vintage Computers]]
[[Category:Capacitor Replacement Guides]]
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