Macintosh IIcx

Macintosh IIcx

Macintosh IIcx (All About Apple museum)
Specifications
Manufacturer	Apple Computer, Inc.
Type	Desktop personal computer
Released	7 March 1989
Discontinued	11 March 1991
Intro price	US$5,369 to US$7,069 at introduction, depending on configuration
CPU	Motorola 68030 at 15.6672 MHz (sold as 16 MHz)
Memory	1 MB or 4 MB; Apple specifies expansion to 128 MB with 120 ns SIMMs
Storage	Optional internal 40, 80 or 160 MB SCSI hard drive
Display	—
Sound	Apple sound chip, 8-bit stereo sampling at 44.1 kHz, four-voice wavetable synthesis
Graphics	None built in; NuBus video card required
ROM	256 KB (not 32-bit clean)
FPU / coprocessor	Motorola 68882
Media	Internal 1.4 MB floppy drive
Ports / interface	Two ADB, two RS-232/RS-422 serial (mini DIN-8), SCSI (DB-25), external floppy (DB-19), stereo sound jack
Expansion	Three NuBus slots
Power	100-240 V AC auto-configured, 50-60 Hz, 90 W maximum
Dimensions	5.5 × 11.9 × 14.4 in (14.0 × 30.2 × 36.5 cm)
Weight	14 lb (6.4 kg) with internal hard drive
OS / Firmware	—
Predecessor	Macintosh IIx
Successor	Macintosh IIci
Model no.	M5650 (Gestalt ID 8)

The Macintosh IIcx is a desktop Macintosh introduced by Apple on 7 March 1989 and sold until March 1991. Apple's developer documentation describes it as the Macintosh IIx with three NuBus slots instead of six and one floppy drive instead of two, in a smaller case with a redesigned power supply and power-on circuit and a 3.5-inch hard drive in place of the IIx's 5.25-inch one. The Macintosh IIci and Macintosh Quadra 700 use the same case, and Apple covers all three in one service manual.

Specifications

Macintosh IIcx specifications (Apple)

Item	Specification
Processor	Motorola 68030 at 15.6672 MHz; 32-bit registers and address/data bus
Coprocessor	Built-in floating-point unit (68882)
RAM	1 MB, expandable to 128 MB with 120 ns or faster SIMMs
ROM	256K
Floppy drive	Internal 1.4 MB; DB-19 port for an external drive
Hard drive	Optional internal 40, 80 or 160 MB
Expansion	Three NuBus slots
Video	None built in
Sound	Apple sound chip: 8-bit stereo sampling at 44.1 kHz, four-voice wavetable synthesis; stereo sound jack
Power	100-240 V AC automatically configured; 50-60 Hz single phase; 90 W maximum, not including the monitor
Size and weight	5.5 × 11.9 × 14.4 in (14.0 × 30.2 × 36.5 cm); 14 lb (6.4 kg) with internal hard drive

Apple prints two clock figures for this processor generation: 15.6672 MHz in the IIcx/IIci/Quadra 700 manual and 15.6772 MHz for the II and IIx in the II/IIx/IIfx manual.

Hardware

Memory and ROM

The IIcx has eight 30-pin SIMM sockets in two banks, marked A and B on the board. Its 256K ROM is not 32-bit clean, so it reports 8 MB unless 32-bit addressing is enabled with MODE32 or Apple's 32-Bit System Enabler; with that software and 16 MB SIMMs it can use 128 MB.

The ROM is four DIP chips at UA1, UA2, UA4 and UA5, and the board also has a ROM SIMM socket at J12. For a dark screen with the drives and fan running, Apple's symptom chart includes "Macintosh IIcx/IIci: Make sure ROM jumper is on".

Battery

The clock and parameter RAM are kept by a 3.6 V lithium cell in a holder on the logic board. Apple's instruction is to measure it on the 10 V DC range, with the positive probe on the end marked "+" on the board, and to replace it if it reads below 2.8 V; the cover, power supply and drive mount come out first. For "clock not running", Apple's first cure is a new battery, then the logic board.

Remove the cell before storing the machine. If it has leaked, neutralise the residue with bicarbonate of soda (not vinegar, which is for alkaline cells), rinse, dry with isopropyl alcohol and check the tracks around the holder on both sides of the board. See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.

Power supply

Apple rates the supply at 90 W maximum with automatic 100-240 V input, publishes no rail tolerances or adjustment, and ends every power fault in its symptom charts at "replace power supply". The supply works from rectified mains, and its reservoir capacitors hold a charge after it is unplugged: discharge them and check with a meter before working on the primary side.

Capacitors

Macintosh IIcx logic board 820F0230-B with the electrolytic capacitors marked (Recap-a-Mac). The battery holder is at lower left, beside the row of six surface-mount capacitors.

Logic board 820F0230-B (Console5 lists it as 820-0230-B) has fifteen electrolytic capacitors. Console5's list and Recap-a-Mac's annotated photograph agree:

Macintosh IIcx logic board 820-0230-B (Console5)

Designators	Value	Voltage	Type
C1, C2, C4, C5, C7, C8, C9, C10, C11	47 µF	16 V	Surface-mount
C15, C16	10 µF	16 V	Surface-mount
C6, C12, C13	470 µF	16 V	Axial
C14	220 µF	16 V	Axial

Six of the surface-mount capacitors sit in a row by the start-up circuit near the battery, and Recap-a-Mac reports that their leakage often leaves a IIcx that will not start at all. Apple published no capacitor list for this board. See Capacitor Failure Symptoms.

Troubleshooting

Selected entries from Apple's symptom charts for the IIcx, IIci and Quadra 700:

Symptom	Apple's cures, in order
No power: black screen, fan off, LED off	Cables; monitor on its own wall socket; power cord; power supply; logic board
Clicking, chirping or thumping	Power supply; logic board
Shuts down intermittently	Clear the side and top vents (thermal protection; recovers after 30-40 minutes); power cord; battery; power supply; logic board
Dark screen; fan, LED and drives working	Monitor brightness; monitor; video cable; move or replace the video card; make sure the ROM jumper is on; SIMMs; logic board; power supply
Works with internal or external SCSI device, not both	External device ID must not be 7 or the internal drive's ID; external terminator; internal drive must have a terminator
Will not eject a disk	Switch on holding the mouse button; eject manually; floppy drive
Clock not running	Battery; logic board

Maintenance notes

• Opening: remove the single Phillips screw at the rear, pull up the tabs and lift the cover off from the front.
• Floppy drive: the internal 1.4 MB drive is a direct-drive mechanism with no belt; see Macintosh Floppy Drive Maintenance.
• Hard drive: see Macintosh HDD Maintenance. The computer is SCSI ID 7.
• Upgrading to a IIci: Apple's kit is a IIci logic board, 80 ns SIMMs, a new bottom case and hard drive power cable. The IIcx's 120 ns SIMMs will not work in the IIci.

Documentation

• Macintosh IIcx/IIci/ Quadra 700 Service Source: Apple's service manual.
• Macintosh II Repair and Upgrade Secrets: Larry Pina's take-apart and upgrade notes for the IIcx (pp. 110-114). A secondary source.

Related pages

• Macintosh IIx, the six-slot machine the IIcx is based on
• Macintosh IIci, the same case with built-in video and a 32-bit clean ROM
• Macintosh Quadra 700, the same case with a 68040
• Capacitor Failure Symptoms
• Recommended Tools