Apple Macintosh 575 Service Manual

Service Source

Macintosh LC 520/550/575

Macintosh LC 520, Macintosh LC 550,

Macintosh LC 575

Service Source

Basics

Macintosh LC 520, 550, 575

Basics Overview - 1

Overview

This manual includes complete repair procedures for the LC 520, LC 550, and LC 575, shown at left.

Figure: Macintosh LC 520, LC 550, LC 575

Basics Product Information - 2

Product Information

Identifying Features

The LC 575 logic board includes a 68LC040 processor, an additional communications slot, and a new hook-and-loopattached battery. The LC 520 and LC 550 do not include these features.

The LC 550 and LC 575 ship with

• the newer manual-inject 1.4 MB Apple SuperDrive and require the keyhole-shaped bezel.

• a revised chassis harness assembly that does not use a floppy drive adapter

• the newer, caddyless CD 300+ CD ROM drive

Basics Product Information - 3

Compatibility Notes

You can exchange the chassis harness assembly of the LC 520 or LC 550 with the newer chassis harness assembly of the LC 575. The newer chassis harness assembly requires the manual-inject floppy drive and caddyless CD ROM drive.

Service Source

Speciﬁcations

Macintosh LC 520, 550, 575

Specifications Processor - 1

Processor

LC 520

LC 550

LC 575

Coprocessor

Motorola 68030 microprocessor 25 MHz Built-in memory management unit (MMU)

Motorola 68030 microprocessor 33 MHz Built-in MMU

Motorola 68LC040 microprocessor 33 MHz Built-in MMU

Socket for optional math coprocessor

Specifications Memory - 2

Memory

RAM

ROM

PRAM

4 MB of dynamic RAM on board Expandable to 36 MB (100 ns or faster SIMMs) 72-pin DRAM SIMM connector

1 MB of ROM

256 bytes of clock/calendar/parameter memory Long-life lithium battery

Specifications Memory - 3

VRAM

512K of VRAM on board (displays up to 256 colors or 8-bit

color)

Expandable to I MB (displays up to 32,000 colors or 16-bit

color) 68-pin VRAM SIMM connector (LC 520) Two VRAM SIMM slots (LC 575)

Specifications Disk Storage - 4

Disk Storage

Floppy Drive

Hard Drive

CD-ROM Drive

Internal 1.4 MB Apple SuperDrive, auto-inject (LC 520) Internal 1.4 MB Apple SuperDrive, manual-inject (LC 550 and

LC 575)

3.5-inch, internal 80, 160, 250, or 320 MB SCSI hard drive

Internal Apple CD 300i CD-ROM drive (LC 520) Internal Apple CD 300+ CD-ROM drive (LC 550 and LC 575)

Specifications I/O Interfaces - 5

I/O Interfaces

Serial

SCSI

Apple Desktop Bus

Processor-Direct Slot

Two RS-232/RS-422 serial ports; mini DIN-8 connectors

One SCSI parallel port; DB-25 connector Connects up to six external SCSI devices

Two Apple Desktop Bus (ADB) ports; mini DIN-4 connectors Maximum of three ADB devices recommended Maximum current draw: 500 mA (Mouse draws 10 mA; keyboard

draws 25 mA.)

Internal expansion slot for 96 or 114-pin processor-direct

expansion cards

Specifications I/O Interfaces - 6

Communications Slot (LC 575)

Sound

Internal expansion for 50-pin modem and Ethernet cards

Sound-output port capable of delivering stereo sound Sound-input port for monaural sound input Front headphone jack capable of delivering stereo sound

Specifications I/O Devices - 7

I/O Devices

Keyboard

Mouse

Microphone

Speaker

Standard 80-key Apple keyboard with numeric keypad; ADB

connector Soft power-on switch

2.5 mm travel, 18 mm vertical and horizontal pitch Two-level tilt adjustment

Apple Desktop Bus Mouse II New, ergonomic design

Built-in electret, omnidirectional microphone

Adjustable sound control on front of bezel

Specifications Sound and Video - 8

Sound and Video

Sound Generator

Video Display

Records at 11 kHz or 22 kHz sample rate Plays back at 22 kHz sample rate Two speakers with enhanced stereo sound Allows playback and recording of ordinary audio compact discs

14-in. diagonal, 13-in. viewable screen Trinitron CRT with high-contrast glass .26-mm aperture grille pitch 640 pixels by 480 lines; 70 dpi

Specifications Electrical - 9

Electrical

Line V oltage

Frequency

Maximum Power

100–240 VAC; Universal power supply

47–63 Hz, single phase

120 W

Specifications Physical - 10

Physical

Dimensions

Weight

Height: 17.9 in. (45.5 cm) Width: 13.5 in. (34.4 cm) Depth: 16.5 in. (42.0 cm)

40.5 lb. (18.4 kg)

Specifications Environmental - 11

Environmental

Operating Temperature

Storage Temperature

Relative Humidity

Altitude

50–104° F (10–40° C)

-40 to 149° F (-40 to 65° C)

20–95% noncondensing

0–10,000 ft. (operating)

Service Source

Troubleshooting

Macintosh LC 520, 550, 575

Troubleshooting General/ - 1

General

The Symptom Charts included in this chapter will help you diagnose specific symptoms related to your product. Because cures are listed on the charts in the order of most likely solution, try the first cure first. Verify whether or not the product continues to exhibit the symptom. If the symptom persists, try the next cure. (Note: If you have replaced a module, reinstall the original module before you proceed to the next cure.)

If you are not sure what the problem is, or if the Symptom Charts do not resolve the problem, refer to the Flowchart for the product family.

For additional assistance, contact Apple Technical Support.

Troubleshooting Symptom Charts/Video - 2

Symptom Charts

Video

Screen is black, too dark, or too bright; audio and drive operate

Screen is bright and audio is present, but no video information is visible

1 Adjust contrast button on front bezel. 2 Adjust brightness. Use Screen Control Panel. 3 Check yoke cable connection. 4 Perform video adjustments. Refer to “Video” in Adjustments

chapter. 5 Perform battery verification. 6 Replace analog board. 7 Replace CRT.

1 Perform video adjustments. Refer to “Video” in Adjustments

chapter. 2 Replace analog board. 3 Replace CRT.

Troubleshooting Symptom Charts/Video

(Continued)

- 3

Single vertical or horizontal line is displayed

Predominant color tint or color cannot be adjusted

Black screen spots (burnt phosphors)

Video

Note:

bottom third of a lit screen. This line is inherent in the design of Trinitron monitors. Do not replace modules.

Otherwise,

1 Replace analog board. 2 Replace CRT.

1 Perform video adjustments. Refer to “Video” in Adjustments

2 Replace analog board. 3 Replace CRT if red, green, or blue cannot be turned off using

Replace CRT.

(Continued)

A thin, gray, horizontal line may be visible across the

chapter.

appropriate controls.

Troubleshooting Symptom Charts/Video

(Continued)

- 4

Picture breaks into diagonal lines, or picture rolls vertically or horizontally

Out of convergence (color bleeds from text or lines)

Flashing or wavy screen or monitor emits high-pitched noise

Video

1 Perform video adjustments. Refer to “Video” in Adjustments

2 Replace analog board.

1 Perform convergence adjustment. Refer to “Convergence” in

2 Replace analog board. 3 Replace CRT.

Replace analog board.

(Continued)

chapter.

Adjustments chapter.

Troubleshooting Symptom Charts/Video

(Continued)

- 5

Video

Screen jitters or flashes

Out of focus 1 Perform focus adjustment. Refer to “Focus” in Adjustments.

Raster size too short/ tall or narrow/wide

1 Verify that adjacent computer equipment is properly

2 Check that all ground cables are secure. 3 Disconnect internal floppy drive, CD-ROM drive, and hard

4 Replace analog board.

2 Replace analog board. 3 Replace CRT only if one part of display remains out of focus

1 Adjust horizontal or vertical size control. Refer to

2 Replace analog board.

(Continued)

grounded. Move electrical devices away from monitor.

Temporarily shut off all fluorescent lights in area.

drive.

despite adjustment of focus controls to their limits.

Adjustments chapter.

Troubleshooting Symptom Charts/Video

(Continued)

- 6

Linearity bad (size of text/graphics differs at top, bottom, or sides of screen)

Raster tilted or shifted

Video

1 Perform video adjustments. Refer to “Video” in Adjustments

2 Replace analog board.

1 Verify that adjacent computer equipment is properly

2 Perform appropriate geometric adjustments. Refer to

3 Perform yoke adjustment. Refer to “Yoke” in Adjustments

4 Replace analog board.

(Continued)

chapter.

grounded. Move electrical devices away from monitor.

Temporarily shut off all fluorescent lights in area.

Adjustments chapter.

chapter.

Troubleshooting Symptom Charts/Video

(Continued)

- 7

Video

Raster not centered 1 Verify that adjacent computer equipment is properly

2 Adjust horizontal or vertical center control. Refer to

3 Replace analog board.

Raster distorted (barrel-shaped, corners not square, stretched or compressed at top of display, or sides not perpendicular)

1 Verify that adjacent computer equipment is properly

2 Perform appropriate geometric adjustments. Refer to

3 Replace analog board. 4 Replace CRT (only in rare instances).

(Continued)

grounded. Move electrical devices away from monitor.

Temporarily shut off all fluorescent lights in area.

Adjustments chapter.

grounded. Move electrical devices away from monitor.

Temporarily shut off all fluorescent lights in area.

Adjustments chapter.

Troubleshooting Symptom Charts/Floppy Drive - 8