Bose Lifestyle AV28 Service Manual

The Bose Lifestyle AV28 is a premium home theater system featuring an Acoustimass module, jewel cube speakers, a media center with integrated amplifier and CD/DVD player, AM/FM tuner, and universal remote control. This service manual provides detailed technical information for qualified service personnel, including system overview, disassembly procedures, circuit diagrams, troubleshooting, and replacement parts. Below are key sections for safety, system architecture, service procedures, diagnostics, and parts information.

1. System Overview 2. Safety Precautions 3. Disassembly Instructions 4. Technical Specifications 5. Circuit Diagrams & Schematics 6. Troubleshooting Flowcharts 7. Test Points & Voltages 8. Firmware & Software 9. Parts List & Exploded Views 10. Reassembly & Calibration 11. Service Contact Information

System Overview

Key components: Media Center (Lifestyle® 28), Acoustimass® Module (Series V), Five Jewel Cube® speakers, Universal Remote Control, Power Cords, Connection Cables.

Component	Description
Media Center	Main control unit with amplifier, CD/DVD player, AM/FM tuner, and input/output connections
Acoustimass Module	Bass reproduction unit with dual drivers and built-in amplifier
Jewel Cube Speakers	Five satellite speakers for front, center, and surround channels
Universal Remote	Controls system functions and compatible external devices
Power Supply	Internal switching power supply for Media Center and module
Connection Panel	HDMI, Component Video, Composite Video, Analog Audio, Digital Audio (Coaxial/Optical), Speaker Terminals
Display	Front panel vacuum fluorescent display (VFD)
Control Buttons	Power, Source Select, Volume, Transport Controls (Play, Stop, etc.)
Ventilation	Cooling fans and heat sinks for thermal management
Protection Circuits	Over-current, over-temperature, and short-circuit protection

Safety Precautions

Before servicing, disconnect AC power. Use appropriate ESD protection.

Disconnect Power: Unplug the system from the AC outlet before opening any enclosure.
ESD Protection: Use grounded wrist strap and anti-static mat when handling circuit boards.
High Voltage: The power supply section contains hazardous voltages even when unplugged. Discharge capacitors before servicing.
Lifting: The Acoustimass module is heavy; use proper lifting technique or assistance.

WARNING! Only qualified service personnel with knowledge of audio/video equipment and electrical safety should perform repairs. Incorrect service can cause shock, fire, or further damage to the equipment.

Disassembly Instructions

Step-by-step guide to access internal components.

Media Center: Remove six Phillips screws from bottom. Slide top cover rearward and lift off.
Acoustimass Module: Remove grille cloth (secured with Velcro). Remove eight screws around driver baffle to access internal amplifier and drivers.
Main Board: After removing top cover, disconnect all ribbon cables and connectors. Remove mounting screws to lift main board assembly.
Power Supply: Located on left side. Disconnect AC inlet and output connectors. Remove four mounting screws.
Drive Mechanism (CD/DVD): Remove front bezel. Disconnect flex cables. Remove transport mounting screws.

CAUTION! Label all connectors before disconnection. Handle flex cables with care to avoid tearing.

Technical Specifications

Amplifier Power: 200 watts total (40W per channel x 5) into 4-8 ohms.
Frequency Response: 35Hz - 20kHz (±3dB).
Signal-to-Noise Ratio: >85dB (A-weighted).
Total Harmonic Distortion: <0.5% at rated power.
Inputs: 3 HDMI (v1.3), 2 Component Video, 3 Composite Video, 4 Analog Audio (RCA), 2 Digital Audio (1 Coaxial, 1 Optical).
Outputs: 5 Speaker terminals, Subwoofer line-out, Composite Video monitor out.
Tuner: AM/FM with 30 station presets.
Disc Compatibility: DVD-Video, DVD-Audio, CD, CD-R/RW, MP3 CD.
Power Requirements: 120V AC, 60Hz, 180W max.
Operating Temperature: 41°F to 95°F (5°C to 35°C).

Circuit Diagrams & Schematics

Reference diagrams for main system blocks.

Main System Block: Shows interconnection between Power Supply, Main Processor, Audio DSP, Amplifier Section, Tuner Module, and Disc Drive.

Power Supply Schematic: Detailed circuit of AC input, rectification, switching regulator (IC501), +5V, +12V, +24V, and -12V rails.

Amplifier Section: Five identical channels using IC701-IC705 (power op-amps) with current limiting and thermal protection.

Audio DSP: Digital signal processor (IC301) for surround decoding, bass management, and room calibration.

Front Panel Control: Microcontroller (IC101) interfacing with buttons, VFD, and IR sensor.

Troubleshooting Flowcharts

Systematic diagnosis for common failures.

No Power: Check AC cord, outlet, internal fuse F501 (5A). Measure +5V standby at TP501.
No Audio (All Channels): Verify source, check main +24V rail at TP502, test audio DSP IC301 clock and reset.
No Audio (Single Channel): Swap speaker connections to isolate. Check corresponding amplifier IC and input coupling capacitors.
No Video: Verify input selection and cable. Check video processor IC401 and output circuits.
Disc Not Reading: Clean lens with approved cleaner. Check disc motor and laser pickup connections. Test focus/tracking coils.
Remote Not Working: Test with known good remote. Check IR receiver (IR101) and +5V supply.
Tuner No Reception: Verify antenna connection. Check tuner module (TU1) power and IF output.

Tip: Use Bose diagnostic test mode (enter 3-8-8 on remote) for system self-test.

Test Points & Voltages

Critical test points for verification.

Test Point	Location	Normal Voltage	Description
TP501	Power Supply Board	+5.1V ±5%	Standby voltage
TP502	Power Supply Board	+24.0V ±5%	Main amplifier supply
TP503	Power Supply Board	+12.0V ±5%	Analog circuits
TP504	Power Supply Board	-12.0V ±5%	Op-amp negative rail
TP301	Main Board (IC301 pin 42)	+3.3V	DSP core voltage
TP302	Main Board (IC301 pin 88)	24.576 MHz	System clock
TP701	Amplifier Board (IC701 pin 4)	0V DC (offset)	Speaker output DC offset (should be <50mV)

WARNING! Measure voltages with respect to chassis ground. Use high-impedance digital multimeter.

Firmware & Software

System software updates and service modes.

Firmware Version: Check via Service Menu (press and hold '1' and '4' on remote while powering on).
Update Procedure: Requires Bose Service Kit (BSK-100) and USB-to-serial adapter. Connect to service port (J901) and use Bose updater software.
Factory Reset: Clears all settings and calibration. In Service Menu, select "Factory Reset".
Calibration Software: ADAPTiQ® calibration requires original microphone. Run via setup menu.

CAUTION! Interrupted firmware update can brick the system. Ensure stable power during update.

Parts List & Exploded Views

Replacement parts with Bose part numbers.

Part Number	Description	Qty
143775	Main Circuit Board Assembly	1
143776	Power Supply Board Assembly	1
143777	Amplifier Heat Sink Assembly	1
143778	Front Panel Assembly (with VFD)	1
143779	CD/DVD Drive Mechanism	1
143780	Laser Pickup (KSS-213C)	1
143781	Acoustimass Module Driver (5.25")	2
143782	Jewel Cube Speaker (complete)	5
143783	Universal Remote Control (black)	1
143784	AC Power Cord (3-prong)	1
143785	Internal Cooling Fan	2
143786	Main Processor (IC201)	1
143787	Audio DSP (IC301)	1
143788	Amplifier IC (STA505)	5
143789	Fuse (5A, 250V, slow-blow)	1

Note: Order parts through authorized Bose service centers only.

Reassembly & Calibration

Post-repair procedures.

Reassembly: Reverse disassembly steps. Ensure all connectors are fully seated and cables routed away from heat sinks.
Power Test: Before final assembly, perform smoke test with current limiter. Verify all voltages.
Basic Function Test: Check power on/off, source selection, volume control, disc playback.
ADAPTiQ Calibration: Required after speaker or amplifier replacement. Use original ADAPTiQ microphone and follow on-screen instructions.
Final Test: Test all inputs (HDMI, analog, digital), all speaker channels, tuner, and remote functions.

Tip: Apply fresh thermal compound when remounting amplifier ICs to heat sink.

Service Contact Information

Bose Corporation Limited Warranty: 1 year on system, 5 years on Acoustimass module and cube speakers.

Authorized Service Centers: Contact Bose for nearest location.

Technical Support: For service personnel: Bose Professional Systems Division.

Website: www.bose.com/service

Phone: 1-800-999-2673 (USA)

Address: Bose Corporation, Service Division, 100 The Mountain Road, Framingham, MA 01701

Service Notes: This manual is proprietary to Bose Corporation. Reproduction without permission is prohibited. Service data subject to change.