Bose Acoustimass 2683 Service Manual

The Bose Acoustimass 2683 is a premium home theater speaker system featuring proprietary waveguide technology, a powered Acoustimass module for deep bass, and five satellite speakers for immersive surround sound. This service manual provides detailed technical information for qualified service personnel, including system overview, specifications, disassembly procedures, circuit diagrams, troubleshooting, and parts lists. Below are key sections for safety, technical specifications, service procedures, and diagnostics.

1. System Overview 2. Safety Precautions 3. Technical Specifications 4. Exploded View & Parts List 5. Disassembly Instructions 6. Circuit Diagrams 7. Module Service (Acoustimass) 8. Satellite Speaker Service 9. Troubleshooting Guide 10. Test Procedures 11. Regulatory & Warranty

System Overview

Key components: Powered Acoustimass bass module, five identical satellite speakers (left, center, right, left surround, right surround), speaker cables, power cord, and remote control (if included with original system).

Component	Description
Acoustimass Module	Powered bass unit with built-in amplifier and crossover network
Satellite Speakers	Five full-range speakers with waveguide technology
Input Panel	Accepts speaker-level inputs from AV receiver/amplifier
Power Supply	Internal switching power supply (100-240V AC, 50/60Hz)
Crossover Network	Directs low frequencies to module, mid/high to satellites
Protection Circuitry	Over-current, thermal, and DC offset protection
Status LED	Indicates power and fault conditions (green/red)
Phase Switch	Adjusts bass module phase relative to satellites
Level Control	Adjusts bass output level
Speaker Terminals	Color-coded push-type connectors for satellite speakers

Safety Precautions

Before servicing, disconnect AC power. Allow capacitors to discharge.

Electrical Safety: Unit contains hazardous voltages. Use insulated tools.
Component Handling: Electrostatic sensitive devices (ESD). Use grounded wrist strap.
Lifting: Bass module is heavy (approx. 15 kg). Use proper lifting technique.
Testing: Use isolation transformer when testing primary side of power supply.

WARNING! Risk of electric shock. No user-serviceable parts inside. Service by qualified personnel only.

Technical Specifications

System Type: 5.1 Home theater speaker system.
Acoustimass Module: Powered, 1 x 8" woofer, built-in 200W amplifier.
Satellite Speakers: 5 x 2.5" full-range drivers with waveguide.
Frequency Response: 45Hz - 20kHz (±3dB).
Crossover Frequency: 180Hz.
Input Impedance: 4-8 ohms (speaker-level).
Power Requirements: 100-240V AC, 50/60Hz, 1.5A max.
Dimensions (Module): 400mm (H) x 250mm (W) x 400mm (D).
Weight (Module): 15 kg.
Operating Temperature: 0°C to 40°C.

Exploded View & Parts List

Reference diagrams show component layout and part numbers.

Acoustimass Module: Chassis, woofer assembly, amplifier board, power supply board, input board, front baffle, rear panel, feet.

Satellite Speaker: Cabinet, driver, waveguide, grille, terminal cup, mounting bracket.

Order parts using Bose part numbers only. Contact Bose Professional Parts.

Disassembly Instructions

Acoustimass Module:

Remove rear panel screws (8x Torx T15).
Carefully pull rear panel assembly away from cabinet.
Disconnect internal wiring harnesses (note positions).
Remove amplifier/power supply assembly (4x screws).
Remove woofer (6x screws around perimeter).

CAUTION! Label all connectors before disassembly. Handle woofer cone with care.

Circuit Diagrams

Includes schematics for: Main amplifier, Power supply, Input buffer/protection, Crossover network.

Power Supply: SMPS topology, UC3842 controller, +/- 45V rails, +12V standby.
Amplifier: Class AB output stage, TDA7294 ICs (or equivalent).
Protection: DC detection, over-current, thermal sensor.
Crossover: 2nd-order low-pass at 180Hz for module.

Tip: Check electrolytic capacitors for bulging/leakage as common failure point.

Module Service (Acoustimass)

Common repairs: Power supply, amplifier ICs, woofer replacement.

No Power: Check fuse F1 (5A, 250V). Test bridge rectifier and main switcher transistor.
No Audio: Verify input signal. Test amplifier ICs for output. Check protection relay.
Distorted Bass: Test woofer voice coil for rubbing. Check amplifier output for DC offset.
Overheating: Clean dust from heatsink. Check fan operation (if equipped).
LED Fault Codes: Solid red = fault. Blinking red = thermal/over-current.

WARNING! Replace amplifier ICs in pairs. Apply thermal compound to heatsink.

Satellite Speaker Service

Remove grille (clips), then 4 screws to access driver.

Driver Replacement: Disconnect leads, note polarity (+/-). Install new driver, ensure seal.

Cabinet Repair: Use wood glue for joints. Fill holes with epoxy putty.

Terminal Cup: Check for loose wires or corrosion.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No sound from module	Blown fuse, faulty power supply	Check F1. Test primary side components. Replace SMPS IC if needed.
Distortion in one channel	Failed amplifier IC, bad capacitor	Measure DC offset at output. Replace TDA7294 and check surrounding components.
Intermittent operation	Loose connection, thermal protection	Reseat all connectors. Check solder joints on power supply. Clean heatsink.
Hum/buzz	Ground loop, failing filter caps	Check AC ground. Replace main filter capacitors (4700uF/63V).
Satellite no sound	Open voice coil, broken wire	Test driver with multimeter (should read ~6 ohms). Check internal wiring.

Reset: Unplug power for 2 minutes to clear protection lockout.

Regulatory & Warranty

FCC Part 15: Class B digital device. CE, RoHS compliant. Copyright © Bose Corporation. This service manual is proprietary and for authorized service centers only. Unauthorized repair may void warranty. For technical support or parts, contact Bose Professional Products Division. Warranty: Typically 5 years limited warranty from date of purchase (check serial number).

Test Procedures

Post-repair verification:

Visual Inspection: Verify all components installed correctly, no loose wires.
Power Up: Connect to variac, slowly increase voltage while monitoring current.
Signal Test: Apply 1kHz test tone at -10dB. Check all channels for clean output.
Frequency Sweep: Verify crossover point (180Hz) and system response.
Load Test: Run at 1/3 power for 30 minutes, monitor temperature.

Service Contact: Authorized Bose Service Center required for warranty repairs.