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Macintosh LC 520/550/575 Service Source

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The Macintosh LC 520, LC 550, LC 575 Service Source is Apple's 176-page service manual for the Macintosh LC 520, Macintosh LC 550 and Macintosh LC 575, the all-in-one machines that share one case, analog board and CRT. The file is Apple's own PDF (Acrobat Distiller 2.1), produced on 5 December 1995, not a scan. It works at module level: specifications, symptom charts, take-apart, the Macintosh Processor Upgrade, battery procedures, display adjustments and an exploded view with part numbers. Page numbers below are the PDF's.

The machines contain a CRT and a mains-powered analog board. Apple's procedures discharge the CRT before the analog board is touched; see CRT Discharge Procedure.

Specifications as printed

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Specifications (pp. 7-17)
Item As printed
Processor LC 520: 68030, 25 MHz; LC 550: 68030, 33 MHz; LC 575: 68LC040, 33 MHz; all with built-in MMU; socket for an optional math coprocessor
RAM 4 MB on board, expandable to 36 MB (100 ns or faster SIMMs); 72-pin SIMM connector
ROM / PRAM 1 MB ROM; 256 bytes PRAM, long-life lithium battery
VRAM 512K on board (8-bit colour), expandable to 1 MB (16-bit); 68-pin VRAM SIMM connector (LC 520); two VRAM SIMM slots (LC 575)
Floppy drive 1.4 MB SuperDrive, auto-inject (LC 520) or manual-inject (LC 550, LC 575)
Hard disk 3.5-inch internal 80, 160, 250 or 320 MB SCSI
CD-ROM AppleCD 300i (LC 520); AppleCD 300+ (LC 550, LC 575)
I/O Two serial (mini DIN-8); SCSI (DB-25), up to six external devices; two ADB, three devices recommended, 500 mA maximum (mouse 10 mA, keyboard 25 mA); PDS for 96- or 114-pin cards; communications slot for 50-pin modem and Ethernet cards (LC 575)
Sound Stereo output port and front headphone jack; mono input; records at 11 or 22 kHz, plays at 22 kHz; two speakers
Display 14-inch diagonal, 13-inch viewable Trinitron; 0.26 mm aperture grille pitch; 640 × 480, 70 dpi
Electrical 100-240 V AC universal supply; 47-63 Hz; 120 W maximum
Physical 17.9 × 13.5 × 16.5 in (45.5 × 34.4 × 42.0 cm); 40.5 lb (18.4 kg)
Environment Operating 10-40 °C; storage −40 to 65 °C; 20-95 % RH; 0-10,000 ft

Contents

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  • Basics: Overview (p. 3); Product Information (pp. 4-5)
  • Specifications: Processor (p. 7), Memory (p. 8), Disk Storage (p. 10), I/O Interfaces (p. 11), I/O Devices (p. 13), Sound and Video (p. 14), Electrical (p. 15), Physical (p. 16), Environmental (p. 17)
  • Troubleshooting: General (p. 19); symptom charts for Video (p. 20), Floppy Drive (p. 26), Hard Drive (p. 29), CD-ROM Drive (p. 30), Peripheral (p. 31), Miscellaneous (p. 34)
  • Take Apart: Rear Housing (p. 38), Fan (p. 41), Analog Board (p. 43), I/O Door (p. 49), Logic Board (p. 51), Drive Bezel (p. 53), Floppy Drive (p. 55), CD-ROM Drive (p. 62), Hard Drive (p. 67), Chassis Harness Assembly (p. 71), CRT (p. 91), Internal Microphone (p. 94), Front Bezel (p. 96)
  • Upgrades: Macintosh Processor Upgrade (p. 99)
  • Additional Procedures: Battery Verification, LC 520 (p. 124) and LC 575 (p. 126); Battery Replacement, LC 520 (p. 128) and LC 575 (p. 131)
  • Adjustments: Geometry (p. 134), Video (p. 142), Convergence (p. 155), Geometric Distortion (p. 158), Yoke (p. 163), Light Meter Setup (p. 169)
  • Exploded View (p. 176)

What it settles

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  • Model differences: the LC 575 board has the 68LC040, a communications slot and a hook-and-loop-mounted battery on a connector. The LC 550 and LC 575 have the manual-inject SuperDrive with a keyhole-shaped bezel, a revised chassis harness without a floppy adapter, and the caddyless AppleCD 300+. The newer harness fits an LC 520 or LC 550 but needs the manual-inject floppy and caddyless CD-ROM drive (pp. 4-5).
  • Battery: replace below 3.0 V on the 10 V DC range. The LC 520 cell sits in a holder whose cover is released with a flat-blade screwdriver at each end; the LC 575 battery is on a connector and a hook-and-loop base (pp. 124-132).
  • Not a fault: a thin grey horizontal line across the lower third of a lit screen is part of the Trinitron design, and Apple says not to replace modules for it (p. 21).
  • Restart after shutdown: remove the test jumper at BD11 on the analog board if one is fitted (pp. 35, 48).
  • Rear cover: five Torx screws; remove any bronze tape on the rear cover shield, bend the centre ground pin back about 1/8 inch, and do not refit the tape (pp. 39-40).
  • CRT safety: never wear a grounding wrist strap until the CRT has been discharged; pull the CRT board straight off the neck, as twisting it can damage the tube (pp. 38, 47).
  • Adjustments: vertical raster 7 in ± 1/8 in (176 mm ± 2 mm), horizontal 9 1/4 in ± 1/8 in (235 mm ± 2 mm), width may vary up to 3/16 in each side with the video timing in use (pp. 138-140); short plastic hex tool, never metal (p. 135); 10-minute warm-up and cutoff before white balance; cutoff after replacing the CRT or analog board (pp. 142-144).
  • Exploded-view part numbers (p. 176): logic boards 661-0812 (LC 520), 661-1830 (LC 550), 661-0867 (LC 575); analog board 661-0192; CRT 661-1666 (661-1667 Australia, 661-1668 Europe); fan 922-1803; floppy drive 661-0474 or 661-0121; CD-ROM drive 661-0222; chassis harness 922-1824; I/O door 922-1827 (922-0704 LC 575); rear housing 922-1835.

What this manual does not contain

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No schematic and no component values; parts are listed at module level only. There are no power-supply voltages, tolerances or adjustments: the Adjustments chapter covers the display only. Its shared VRAM entry ("expandable to 1 MB") is right for the LC 575; the LC 520 takes one 256 KB SIMM for 768 KB (see Macintosh LC 520 Developer Note). The Bulletins/Safety chapter that the procedures refer to is not in this file.

Pages that cite this document

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Download: Lc_520.550.575.pdf (1.5 MB)

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