Macintosh LC 630 Capacitor Replacement Guide

Replacing the surface-mount electrolytic capacitors in the Macintosh LC 630 is essential maintenance. This guide covers the LC 630, the Quadra 630, the Performa 630 series and the LC 630 DOS Compatible, which share a logic board design.

Despite the name, the 630 has nothing in common with the LC "pizza box" machines. It is a different computer on a different board with a different power supply, an IDE hard drive instead of SCSI, and a 1 MB DRAM frame buffer instead of VRAM. Do not carry capacitor lists across from the LC, LC III or LC 475 pages.

Which board you have

The board photographed by Recap-a-Mac is marked 820-0548-B, copyright 1994. Apple does not use the 820- number in its service literature; it identifies the board by finished-assembly part number, and there are four:

Apple logic board part numbers, 630 series

Part number	Fitted to	DRAM
661-0158	LC 630, Performa 630 series (non-DOS)	One SIMM slot, 36 MB maximum
661-0189	Quadra 630	—
661-1114	LC 630 DOS Compatible	Two SIMM slots, 52 MB maximum
661-1115	DOS Compatible, international only	—

The number of DRAM SIMM slots is the quickest way to tell a one-slot board from a two-slot one.

Symptoms of capacitor failure

• Sound faults. Lost, weak or distorted output is the usual first sign. One exception worth ruling

 out first: Apple documents a crackling noise on sounds other than system beeps that is a software
 problem, fixed by Audio Volume Extension 1.1 or later, not a capacitor problem.

• Intermittent or failed starting, often temperature-dependent.
• Brown or amber residue around the capacitor bases, dull solder mask, and green or white deposits

 where electrolyte has reached copper. Assume trace damage at that point and buzz out every trace
 leaving a capacitor pad.

A small SMD electrolytic of this era usually fails by seeping, not by bulging. A flat-looking capacitor is not a healthy one. See Capacitor Failure Symptoms.

Two faults that look like capacitor failure on this machine but are not:

• Dark screen with audio and drives working and the fan running. Apple's first two checks are the

 video connections and the monitor-out daughterboard connection on the fan bracket — the
 630's DB-15 video output lives on a daughterboard carried by the fan bracket, not on the logic board
 itself.

• Nothing at all, fan not running, LED not lit. The 630 has no mechanical power switch; it powers

 on exclusively through the soft power key on the keyboard. Apple's chart checks external power, then a
 known-good keyboard, then reseating the logic board, then unplugging the 4.5 V battery for twenty
 seconds before anything is replaced.

Logic board capacitors

Nine surface-mount electrolytic capacitors:

• 6 × 47 µF 16 V
• 3 × 100 µF 6.3 V

Macintosh LC 630 logic board 820-0548-B, with each electrolytic marked with its value, working voltage and positive terminal. Source: Recap-a-Mac.

On designators. The annotated photograph above is the location map, and it is deliberately used in place of a designator table here. The 630 board carries well over sixty capacitor positions, numbered into the C60s, and the nine electrolytics are scattered among them — C3 is a 100 µF, C41 and C43 are 47 µF, and so on. Any list that assigns them to a neat run such as C1–C9 is not describing this board. Work from the photograph, and read the value printed on each capacitor body before you lift it.

On sourcing. These figures come from a single community source, Recap-a-Mac. Console5 does not carry a 630-series entry, and Apple's Service Source for this machine is module-level: it tells you to replace the logic board, not which capacitor is on it.

Replacement parts

Match capacitance; a higher working voltage is acceptable and usually preferable. 47 µF 16 V positions take a 25 V part comfortably; 100 µF 6.3 V positions take a 10 V or 16 V part. Buy from a distributor that will tell you the manufacturer.

Tantalum replacements are popular and long-lived, but they fail short and are unforgiving of reversed polarity. Either type is fine here — unlike the LC III, the 630 board has no known silkscreen error.

Replacement procedure

Getting the board out

The 630 is designed for this: remove the rear plastic panel and slide the logic board out of the chassis. Nothing else has to come apart.

1. Disconnect the mains lead and everything else.
2. Remove the rear plastic panel and slide out the board.
3. Photograph the board at high enough resolution to read the silkscreen before you touch anything.

Removal and fitting

1. Add a little fresh solder to both joints of each capacitor — it improves heat transfer and lets you work cooler.
2. Heat one pad while gently rocking the can, alternating pads until it releases. Hot air at both pads works too.
3. Wick the pads clean and wash the area thoroughly with isopropyl alcohol and a soft brush, working outwards.
4. Inspect under magnification and check continuity on every trace leaving a capacitor pad. Corrosion travels under solder mask and does not show from above.
5. Fit the new parts one pad at a time, checking orientation against your photographs.
6. Clean off the flux, inspect the joints, and check for shorts between each supply rail and ground at the power connector before powering up.

If electrolyte has reached the copper, follow the cleaning and trace-repair guidance on Battery Explosion, Capacitor or Corrosion Damage rather than improvising. Do not reach for vinegar on capacitor leakage: it is the standard neutraliser for alkaline battery residue, which is a different problem, and leaving acetic acid on a board causes its own corrosion.

The processor

The 68LC040 (68040 on the Quadra 630) sits in a socket. Apple's own upgrade procedure removes it with a dedicated processor removal tool, ordered as a separate service part. If you take it out to get at the board, use the proper tool — levering a PGA out with a screwdriver bends pins.

Power supply

The 630's power supply is a separate sealed module, Apple part 661-0170. Apple specifies the machine at 100–240 VAC, 50–60 Hz, 45 W maximum excluding the monitor.

You are free to open and recap it; it is an ordinary mains-fed switch-mode supply and the usual precautions apply. With the cover off and the lead in, the fuse, input filter, rectifier and bulk capacitor sit at mains potential, and the bulk capacitor holds charge at roughly the peak of the incoming waveform — around 170 V on a 120 V supply, around 340 V on a 230 V supply — for some time after the plug comes out. Unplug, wait, and measure across the bulk capacitor before touching the primary side.

No capacitor list for the 630 power supply was found while this page was verified. Apple does not publish one and no community list was located. Read the values off the parts in your own supply; do not use a list from another machine.

Apple's Service Source contains no rail-voltage tolerance table and no power supply adjustment procedure for this machine. Where a symptom points at power, its instruction is to replace the supply as a module. If you see rail tolerances or a "adjust the PSU potentiometer" step quoted for a 630, treat it as unsourced.

DOS Compatibility Card

The LC 630 DOS Compatible ships with three extra boards: the DOS-Compatible board itself, a sound daughterboard, and an adapter board in the processor-direct slot, plus a DRAM SIMM on the main logic board. Apple's take-apart sequence disconnects the 26-pin adapter board cable, lifts the battery end of the adapter board out of the PDS, then removes the sound board's two Phillips screws.

Inspect all three boards while you have the machine apart — they are the same age as the logic board. Apple identifies a specific sound-card fault on DOS-compatible machines and gives the replacement part as 661-0253.

Related pages

• Macintosh LC 630
• Macintosh LC 630 General Maintenance
• Macintosh LC 630 Troubleshooting
• Macintosh LC 630 DOS Compatible
• Macintosh Quadra 630
• Macintosh Performa 630
• LC 630/Quadra 630/ Performa 640 Service Source
• Capacitor Failure Symptoms