Apple Desktop Bus Mouse II

Apple Desktop Bus Mouse II
Apple Desktop Bus Mouse II (Model M2706)
Manufacturer	Apple Computer, Inc.
Type	Pointing device
Discontinued	May 6, 1998
Price	US$89 (retail)
Interface	Apple Desktop Bus
Compatible	All ADB-equipped Macs, Apple IIGS, PowerBook (with adapter)
Dimensions	108 mm L × 62 mm W × 38 mm H
Weight	140 g (4.9 oz)
Predecessor	Apple Desktop Bus Mouse
Successor	Apple USB Mouse
Model	M2706 (Platinum), M2706 (Black), M2707 (PowerBook Gray)

The Apple Desktop Bus Mouse II was the second and final Apple Desktop Bus mouse produced by Apple Computer, introduced in January 1993. Marking Apple's third major mouse redesign in a decade, it abandoned the angular blocky design of its predecessor for a curved, ergonomic "teardrop" shape that influenced mouse design industry-wide. The mouse served as the standard pointing device for all Macintosh desktop computers from 1993 until its discontinuation on May 6, 1998, when it was replaced by the Apple USB Mouse accompanying the original iMac.

Design Evolution

The Apple Desktop Bus Mouse II represented a significant departure from Apple's previous angular mouse designs, drawing inspiration from the successful third-generation Microsoft Mouse. The teardrop-shaped body featured smooth, rounded curves with the tracking ball positioned forward of center and an enlarged button encompassing the entire front portion of the mouse. This ergonomic design proved so successful that it established the basic form factor for computer mice that persists in modern designs across the industry.

The mouse maintained Apple's commitment to single-button simplicity, with the button spanning approximately 40% of the mouse surface area. The smooth curves eliminated the sharp edges of earlier models while maintaining an ambidextrous design suitable for both left and right-handed users.

Model Variants

Three distinct color variants were produced during the mouse's five-year production run:

M2706 Platinum

The standard Platinum gray version (Pantone 423C) shipped with all Macintosh desktop computers from 1993-1998. This was the most common variant, matching Apple's standard computer coloring of the era.

M2706 Black

A rare black version was produced exclusively for:

• Macintosh TV (1993-1994)
• Macintosh Performa 5420 (European and Asian markets only)

The black variant featured identical internals but commanded premium prices on the collector market due to its scarcity.

M2707 PowerBook Gray

A dark gray version matching the PowerBook 100 series aesthetic was offered as an optional accessory for PowerBook users. Model M2707 featured the same internal design but utilized the darker "Smoke" gray coloring to coordinate with portable systems.

Manufacturing Variations

Four distinct internal designs were produced across different manufacturing facilities:

Taiwan Manufacture (Logitech)

Characteristics:

• Black tracking ball (19mm)
• Black ball cage
• Removable cable assembly
• Two screws under label
• PCB: Logitech 200343
• Part numbers: 400791-400793, 400685

Identification: Large label with two screws, serial numbers starting with 'M'

China Manufacture

Characteristics:

• Gray tracking ball (22mm)
• Integrated ball cage (no separate component)
• Single screw under serial number sticker
• Two-piece PCB design with Logitech controller
• Stamped label (unique among variants)

Identification: Serial numbers starting with 'L', second letter 'C' for China

Ireland/Malaysia Manufacture (Mitsumi)

Characteristics:

• Gray tracking ball (22mm)
• Separate ball cage component
• Single consolidated PCB
• Mitsumi controller chip
• Embossed text in plastic case

Identification: Serial numbers starting with 'M', second letter 'I' (Ireland) or 'B' (Malaysia)

USA Manufacture

Characteristics:

• Gray tracking ball
• White or black ball cage
• Three-screw PCB mounting
• Various controller chips

Identification: Serial numbers with USA designation

Technical Specifications

Physical Specifications

• Dimensions: 108mm × 62mm × 38mm
• Weight: 140g (without cable)
• Cable length: 1.2m (4 feet)
• Button: Single mechanical button
• Tracking: Opto-mechanical ball system

Tracking System

• Ball diameter: 19mm (early) or 22mm (later models)
• Resolution: 100 counts per inch (CPI)
• Encoder wheels: 36-slot optical
• Maximum tracking speed: 10 inches/second
• Sampling rate: 200 Hz mechanical

Electrical Specifications

• Interface: Apple Desktop Bus (ADB)
• Connector: 4-pin mini-DIN
• Power consumption: 50mA typical, 100mA maximum
• Operating voltage: 4.75V - 5.25V

ADB Protocol

• Device address: $3 (default)
• Handler ID: $01 (standard mouse)
• Polling rate: 100 Hz typical
• Data format: 2-byte movement packets

Internal Components

Controller Chips

Various manufacturers supplied controller ICs:

• Logitech: Custom ADB controller (Taiwan models)
• Mitsumi: Proprietary ASIC (Malaysia/Ireland models)
• IC Designs: Custom controller (some variants)

Mechanical Components

• Microswitch: Omron D2F series or equivalent
• Encoder wheels: Injection-molded plastic with 36 slots
• LED/Phototransistor pairs: Infrared 940nm
• Ball: Rubber-coated steel (black) or solid rubber (gray)

Circuit Board Design

Two primary PCB configurations existed:

• Single board: Most common, integrated design
• Dual board: Separate boards for switch and electronics (China manufacture)

Maintenance & Repair

Disassembly Procedure

The disassembly process varied by manufacturing variant:

Taiwan models (two screws):

1. Locate screw positions under label edges
2. Pierce label or carefully peel to access screws
3. Remove Phillips screws
4. Separate case halves gently

Later models (single screw):

1. Find screw under serial number sticker
2. Remove single Phillips screw
3. Release internal clips carefully
4. Separate case halves

Common Maintenance Tasks

Ball and Roller Cleaning

Required tools: Isopropyl alcohol (90%+), cotton swabs, compressed air

Procedure:

1. Rotate ball retainer counterclockwise to remove
2. Extract tracking ball
3. Clean ball with isopropyl alcohol
4. Clean encoder wheels with cotton swab
5. Remove debris from encoder slots with compressed air
6. Verify roller spring tension
7. Reassemble in reverse order

Microswitch Replacement

Compatible switches:

• Omron D2F-01, D2F-01F, D2F-01F-T
• Panasonic EVQ-P0E07K (light touch)
• Panasonic EVQ-P0D07K (firm touch)

Replacement procedure:

1. Disassemble mouse completely
2. Desolder failed switch (note orientation)
3. Clean PCB pads with flux and wick
4. Install new switch maintaining alignment
5. Test operation before reassembly

Cable Repair

Common failure points:

• Cable entry to mouse body
• Strain relief area
• Near connector

Repair options:

• Splice repair at break point
• Complete cable replacement
• Reinforcement with heat shrink tubing

Troubleshooting Guide

Common Issues and Solutions

Symptom	Likely Cause	Solution
Erratic cursor movement	Dirty encoder wheels	Clean wheels and ball thoroughly
No cursor movement	Broken cable, failed encoder	Test cable continuity, check encoders
Button doesn't click	Worn microswitch	Replace switch with compatible part
Intermittent operation	Cable damage, dirty contacts	Check cable, clean connectors
Double-clicking	Switch bounce	Replace microswitch
System doesn't recognize	ADB port issue	Test on different port/system

Preventive Maintenance

Monthly:

• Clean ball and check movement
• Inspect cable for damage

Quarterly:

• Deep clean including encoder wheels
• Check button operation
• Clean ADB connector

Annually:

• Full disassembly and cleaning
• Inspect PCB for damage
• Test on known-good system

Modern Retrofits

Optical Sensor Conversion

TT Design offers retrofit boards that replace the mechanical ball system with modern optical sensors:

• Model-specific boards for different manufacturing variants
• PixArt optical sensor technology
• Maintains original 100 CPI specification
• USB-C configuration port for adjustment
• Compatible with original ADB protocol

USB Conversion

While the mouse can be used with ADB-to-USB adapters (Griffin iMate, Wombat), internal USB conversion requires significant modification and is generally not recommended due to the availability of purpose-built adapters.

Parts & Specifications

Replacement Parts

Service Parts Reference

Component	Specification	Notes
Tracking ball	19mm or 22mm diameter	Variant-specific
Microswitch	Omron D2F series	Universal fit
Ball retainer	Model-specific	Not interchangeable between variants
Encoder wheels	36-slot optical	Donor part required
Cable assembly	4-conductor shielded	Some models detachable

Cleaning Supplies

• Isopropyl alcohol 90%+
• Lint-free cotton swabs
• Compressed air
• Plastic-safe contact cleaner
• Microfiber cloths

Historical Impact

The Apple Desktop Bus Mouse II's teardrop design proved remarkably influential in the computer industry. The ergonomic shape established design principles that influenced not only subsequent Apple mice but also became widely adopted by other manufacturers. The curved form factor addressed ergonomic concerns while maintaining Apple's design philosophy of simplicity and elegance.

Despite criticism for retaining the single-button design when multi-button mice were becoming standard on other platforms, the mouse served successfully throughout the PowerPC transition era. Its five-year production run saw it bundled with systems ranging from the Quadra series through the Power Macintosh G3.

Software Compatibility

System Requirements

• Minimum: System 7.1
• Maximum: Mac OS 9.2.2
• Optimal: System 7.5 through Mac OS 8.6

Control Software

• Mouse control panel: Standard tracking speed adjustment
• Third-party utilities: SteerMouse, USB Overdrive (with adapters)
• Accessibility: CloseView, Easy Access

Collector Information

Authentication

• Check serial number format for manufacturing location
• Verify label type (printed vs. embossed)
• Confirm ball color matches variant
• Inspect internal PCB configuration

Condition Grading

• Mint: No yellowing, perfect button action
• Excellent: Minimal yellowing, fully functional
• Good: Moderate yellowing, normal wear
• Fair: Significant yellowing, functional issues

Market Value

• Platinum M2706: Common, modest value
• Black M2706: Rare, commands premium
• Gray M2707: Uncommon, moderate premium

Restoration

• Retrobrighting: Effective but may damage texture
• Case swapping: Possible between compatible variants
• Internal upgrades: Optical conversion available

Production Statistics

While exact production numbers remain unpublished, the Apple Desktop Bus Mouse II was manufactured continuously from 1993 to 1998, with estimates suggesting over 6 million units produced across all variants. The Platinum version comprised approximately 95% of production, with black variants accounting for less than 2% of total units manufactured.

Legacy

The Apple Desktop Bus Mouse II represented the culmination of Apple's ADB-era input device development. Its ergonomic design successfully bridged the gap between Apple's early angular aesthetic and the organic forms that would characterize later products. The mouse's influence extended beyond Apple, with the teardrop shape becoming a de facto standard for mouse design throughout the 1990s.

The transition to USB with the original iMac in 1998 marked the end of the ADB era, but the Desktop Bus Mouse II's design DNA lived on in the controversial "hockey puck" USB Mouse, which attempted to further refine the circular ergonomic concept, though with less success.

See Also

• Apple Desktop Bus
• Apple Desktop Bus Mouse
• Apple USB Mouse
• ADB Protocol Specification