Bose AV38 Media Center Service Manual

The Bose AV38 Media Center is a premium home entertainment system featuring a 5-disc DVD/CD changer, AM/FM tuner, integrated amplifier, and proprietary Bose speaker technology. This service manual provides detailed information for authorized technicians on safety procedures, system overview, disassembly instructions, troubleshooting, parts lists, and calibration procedures for the AV38 model. Below are key sections for service and maintenance.

1. Safety Precautions 2. System Overview & Specifications 3. Disassembly Instructions 4. Circuit Diagrams & Block Diagrams 5. Troubleshooting Flowcharts 6. Parts List & Exploded Views 7. Calibration & Adjustment Procedures 8. Firmware Update Instructions 9. Reassembly & Testing 10. Regulatory & Compliance Information 11. Common Faults & Solutions

Safety Precautions

Before servicing, disconnect AC power. Use ESD protection. Note high-voltage areas.

Warning	Description
Electrical Shock Hazard	Disconnect power before servicing. Capacitors may retain charge.
ESD Sensitivity	Use grounded wrist strap and anti-static mat when handling PCBs.
Laser Safety	DVD mechanism contains a Class 1 laser. Do not view directly or disassemble optical assembly.
Mechanical Hazards	Exercise caution with moving parts in disc changer mechanism.
Heat Sinks	Allow amplifier heat sinks to cool before handling.

System Overview & Specifications

Key components: Main Control Board, Power Supply Unit, DVD/CD Changer Mechanism, Amplifier Module, Tuner Module, Front Panel Display.

Amplifier Section: 5-channel (center, front L/R, surround L/R), proprietary Bose digital amplification.
Disc Changer: 5-disc capacity, compatible with DVD, DVD-R/RW, CD, CD-R/RW, MP3 CD.
Tuner: AM/FM with 30 station presets.
Inputs/Outputs: Composite Video, S-Video, Component Video (YPbPr), Analog Audio (RCA), Digital Coaxial, Digital Optical, Speaker terminals.
Power Requirements: 120V AC, 60Hz, 180W max.
Dimensions (Main Unit): 16.5" W x 4.1" H x 13.2" D.

WARNING! For authorized service personnel only. Unauthorized modifications void warranty.

Disassembly Instructions

Procedure to access internal components.

Power off and unplug the unit. Remove all connected cables.
Remove the top cover: Unscrew 6 Phillips screws (2 front, 2 rear, 2 sides).
Remove the front bezel: Carefully release 4 plastic clips (top and bottom).
Remove the main board shield: Unscrew 4 screws securing the metal shield.
To access power supply: Disconnect all connectors, unscrew 4 mounting screws.
To access disc mechanism: Remove mechanism mounting bracket (4 screws).

CAUTION! Label all connectors before disconnecting. Handle ribbon cables with care.

Circuit Diagrams & Block Diagrams

Main System Block Diagram: Shows signal flow between tuner, DVD, DSP, amplifier sections.
Power Supply Schematic: +5V, +12V, +3.3V, +/-15V rails, protection circuits.
Amplifier Module Schematic: Detailed circuit for each channel with component designators.
Front Panel Control Schematic: Microcontroller, buttons, display interface.
Disc Mechanism Interface: Motor drivers, laser pickup connections.

Troubleshooting Flowcharts

Access service mode: Hold 'Setup' + 'Mute' on remote while powering on.

No Power: Check AC cord, fuse F101 (5A), primary power supply voltages.

No Disc Playback: Check disc mechanism power, laser pickup, spindle motor.

No Audio Output: Verify amplifier module voltages, speaker connections, DSP output.

Display Issues: Check front panel ribbon cable, display driver IC, +5V supply.

Tuner Not Working: Verify antenna connection, tuner module power, I2C bus.

Parts List & Exploded Views

Key replaceable parts with Bose part numbers.

Main Control Board: Part #123456
Power Supply Board: Part #123457
DVD/CD Mechanism Assembly: Part #123458
Laser Pickup (KSS-213C): Part #123459
Front Panel Assembly: Part #123460
Amplifier Module: Part #123461
Remote Control (RC-10): Part #123462
AC Power Cord: Part #123463
Rubber Feet (Set of 4): Part #123464

Tip: Always use genuine Bose replacement parts.

Calibration & Adjustment Procedures

Requires service remote or entering service mode.

Enter Service Mode: As described in troubleshooting.
Audio Channel Balance: Adjust level trimmers on amplifier board for equal output.
Laser Power Adjustment: Use oscilloscope on test point TP101; adjust RV101 for 1.2Vpp.
Disc Speed Calibration: Use test disc; adjust FG gain in service menu.
Display Contrast: Adjust RV201 on front panel board for optimal visibility.
Tuner Alignment: Requires RF signal generator; adjust coils L101, L102 for peak reception.

WARNING! Laser adjustment requires specific training. Incorrect adjustment can damage pickup.

Firmware Update Instructions

Using service USB port or CD-based update.

Procedure: Download latest firmware from Bose service portal. Extract to USB drive (FAT32). Power off unit. Insert USB into service port (rear). Hold 'Skip Forward' + 'Power' on front panel. Release when 'UPDATE' appears on display. Do not power off during update (approx. 3 minutes). Unit will reboot automatically.

Reassembly & Testing

After service, reassemble in reverse order of disassembly. Perform full functional test.

Verify all screws are tightened, no cables pinched.
Power on, check display initialization.
Test disc playback with known-good DVD and CD.
Test all audio channels with test tone (service menu option).
Test all inputs (AUX, TUNER, VIDEO).
Test remote control functions.
Run system diagnostics (service menu).

CAUTION! Ensure proper grounding of all shields. Verify cooling airflow is not obstructed.

Regulatory & Compliance Information

FCC ID: A94AV38 (Complies with Part 15). IC: 511B-AV38. UL Listed. Laser Compliance: FDA CDRH Class 1. Contains lead in solder; follow WEEE disposal guidelines. Copyright © Bose Corporation. This service manual is proprietary and for authorized use only. For technical support, contact Bose Service Division.

Common Faults & Solutions

Symptom	Possible Cause	Corrective Action
Unit dead, no power LED	Blown fuse, faulty power supply	Check/Replace F101 (5A). Check diodes D101-D104, switching IC U101.
Disc changer won't load	Worn loading belt, faulty mode switch	Replace loading belt (Part #123465). Clean/replace mode switch S101.
No audio from one channel	Failed output IC, bad solder joint	Replace amplifier IC U301 (channel specific). Reflow solder on output connectors.
Display shows "Err 3"	Disc mechanism communication fault	Check ribbon cable from mechanism to main board. Replace mechanism controller IC U401.
Intermittent shutdown	Overheating, faulty thermal sensor	Clean vents/fans. Check thermal sensor TH101. Replace if open circuit.

Reset Procedure: Unplug unit, wait 60 seconds, plug back in.

Bose Service: 1-800-999-2673; www.bose.com/service