Apple macintosh plus Service Manual

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Service Source

Macintosh Plus

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Service Source

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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Service Source

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

ROM

PRAM

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

128K

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

SCSI

Mouse

Keyboard

Serial

External drive port; DB-19 connector

One SCSI parallel port; DB-25 connector

Mouse port; DE-9 connector

Synchronous serial keyboard bus; RJ-11 connector

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

Specifications I/O Devices - 6

I/O Devices

Keyboard

Mouse

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

connector

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

Video Display

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

22-kHz sampling rate

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

Specifications Electrical - 8

Electrical

Line V oltage

Frequency

Maximum Power

105–125 VAC

50–60 Hz

60 W

Specifications Physical - 9

Physical

Dimensions

Weight

Height: 13.6 in. (34.5 cm)
Width: 9.6 in. (24.4 cm)
Depth: 10.9 in. (27.6 cm)

16 lb. 8 oz. (7.5 kg)

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Service Source

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

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

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.

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”

Unable to insert disk
all the way

1 Replace bad disk.
2 Replace floppy drive cable.
3 Replace floppy drive.
4 Replace logic board. Retain customer’s SIMMs.

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)

- 4

Does not read disks
on internal drive

Does not read disks
on external drive

Drives

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.

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.

(Continued)

Troubleshooting Symptom Charts/Drives

(Continued)

- 5

Audio tone sounds at
power on, video is
present, but drive
does not operate

Drive runs
continuously

400K drive does not
boot

Drives

1 Replace floppy drive cable.
2 Replace floppy drive.
3 Replace logic board. Retain customer’s SIMMs.

1 Replace bad disk.
2 Replace floppy drive cable.
3 Replace floppy drive.
4 Replace logic board. Retain customer’s SIMMs.

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

2 Replace floppy drive.

(Continued)

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

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

No response to any
key on keyboard

No response from a
particular key

1 Replace mouse.
2 Replace logic board. Retain customer’s SIMMs.

1 Replace keyboard cable.
2 Replace keyboard.
3 Replace logic board. Retain customer’s SIMMs.

1 Replace keyswitch.
2 Replace keyboard.
3 Replace logic board. Retain customer’s SIMMs.

Troubleshooting Symptom Charts/Peripherals

(Continued)

- 7

Known-good
ImageWriter or
ImageWriter II does
not print

Known-good
LaserWriter does not
print

Peripherals

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.

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.

(Continued)