Apple macintosh plus Service Manual

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Macintosh Plus

Service Source

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Basics

Macintosh Plus

Basics Overview - 1

Overview

This manual contains

complete repair procedures

for the Macintosh Plus,

shown at left.

Figure: Macintosh Plus

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Specifications

Macintosh Plus

Specifications Introduction - 1

Introduction

Specifications information for this product can be found in this chapter and also in the

Spec Database, which you can access in one of three ways:

— Launch it directly by double-clicking the Apple Spec Database runtime alias at the top

level of the Main Service Source CD.

— Select "Apple Spec Database" from the Service Source drop-down main menu.

— Click the Acrobat toolbar icon for the database, which is near the right end of the

toolbar with the letters "SP."

Specifications Processor - 2

Processor

CPU

Motorola 68000 microprocessor

7.83 MHz

32-bit internal data bus

Specifications Memory - 3

Memory

RAM

1 MB, expandable to 4 MB (150 ns or faster SIMMs)

ROM

128K

PRAM

CMOS custom chip with 4.5 V, user-replaceable battery backup

(includes 256 bytes of memory; remembers system

parameters even with the machine switched off)

Specifications Disk Storage - 4

Disk Storage

Floppy Drive

Internal, double-sided drive: uses 3.5-in., hard-case floppy

disks—either double-sided, 800K capacity or single-sided,

400K capacity

Specifications I/O Interfaces - 5

I/O Interfaces

Floppy Drive

External drive port; DB-19 connector

SCSI

One SCSI parallel port; DB-25 connector

Mouse

Mouse port; DE-9 connector

Keyboard

Synchronous serial keyboard bus; RJ-11 connector

Serial

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

Specifications I/O Devices - 6

I/O Devices

Keyboard

78 keys, including numeric keypad and cursor keys; RJ-11

connector

Mouse

Mechanical tracking; optical shaft encoding at 3.54 pulses per mm

(90 pulses per in.) of travel; DE-9 connector

Specifications Sound and Video - 7

Sound and Video

Sound Generator

Four-voice sound with 8-bit digital/analog conversion, using

22-kHz sampling rate

Video Display

9-in. (diagonal) screen; 512 by 342 pixel, bit-mapped display

Specifications Electrical - 8

Electrical

Line V oltage

105–125 VAC

Frequency

50–60 Hz

Maximum Power

60 W

Specifications Physical - 9

Physical

Dimensions

Height: 13.6 in. (34.5 cm)

Width: 9.6 in. (24.4 cm)

Depth: 10.9 in. (27.6 cm)

Weight

16 lb. 8 oz. (7.5 kg)

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Troubleshooting

Macintosh Plus

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

No video, but audio

tone is present and

drive operates

1 Turn contrast control fully clockwise.

2 Check video cable connections.

3 Replace power supply board.

4 Replace neck cable.

5 Replace logic board. Retain customer’s SIMMs.

Screen is bright and

audio is present, but

no video information

is present

1 Replace power supply board.

2 Replace logic board. Retain customer’s SIMMs.

Troubleshooting Symptom Charts/Drives - 3

Drives

Disk ejects; display

shows disk icon with

blinking “X”

1 Replace bad disk.

2 Replace floppy drive cable.

3 Replace floppy drive.

4 Replace logic board. Retain customer’s SIMMs.

Unable to insert disk

all the way

1 Insert paper clip into small hole beside drive slot, or switch

off system power and hold mouse button down while

switching system power back on to complete eject cycle.

Then insert disk with metal slot forward and write-protect tab

on bottom.

2 Replace floppy drive.

Troubleshooting Symptom Charts/Drives

(Continued)

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Drives

(Continued)

Does not read disks

on internal drive

1 Replace bad disk.

2 Replace floppy drive cable.

3 Replace Mylar RFI shield.

4 Replace floppy drive.

5 Verify ROMs on the logic board.

6 Replace logic board. Retain customer’s SIMMs.

Does not read disks

on external drive

1 Replace bad disk.

2 Replace floppy drive cable.

3 Replace Mylar RFI shield.

4 Replace external drive.

5 Verify ROMs on the logic board.

6 Replace logic board. Retain customer’s SIMMs.

Troubleshooting Symptom Charts/Drives

(Continued)

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Drives

(Continued)

Audio tone sounds at

power on, video is

present, but drive

does not operate

1 Replace floppy drive cable.

2 Replace floppy drive.

3 Replace logic board. Retain customer’s SIMMs.

Drive runs

continuously

1 Replace bad disk.

2 Replace floppy drive cable.

3 Replace floppy drive.

4 Replace logic board. Retain customer’s SIMMs.

400K drive does not

boot

1 If logic board has Rev. A ROMs and drive stepper motor is

serial number F518 or higher, upgrade to Rev. B ROMs.

2 Replace floppy drive.

Troubleshooting Symptom Charts/Peripherals - 6

Peripherals

Cursor does not move 1 Connect mouse.

2 Clean mouse.

3 Replace mouse.

4 Replace logic board. Retain customer’s SIMMs.

Cursor moves but

clicking mouse

produces no response

1 Replace mouse.

2 Replace logic board. Retain customer’s SIMMs.

No response to any

key on keyboard

1 Replace keyboard cable.

2 Replace keyboard.

3 Replace logic board. Retain customer’s SIMMs.

No response from a

particular key

1 Replace keyswitch.

2 Replace keyboard.

3 Replace logic board. Retain customer’s SIMMs.

Troubleshooting Symptom Charts/Peripherals

(Continued)

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Peripherals

(Continued)

Known-good

ImageWriter or

ImageWriter II does

not print

1 Make sure that Chooser and Control Panel are set correctly.

2 Check that system software version is compatible. Replace

software with known-good.

3 Reset PRAM.

4 Replace interface cable.

5 Replace logic board. Retain customer’s SIMMs.

Known-good

LaserWriter does not

print

1 Make sure that Chooser and Control Panel are set correctly.

2 Check that system software version is compatible. Replace

software with known-good.

3 Reset PRAM.