Bose SA 3-2-1II Service Manual

The Bose SA 3-2-1II is a high-performance DVD home entertainment system featuring a media center, two direct/reflecting cube speakers, and an Acoustimass module. This service manual provides detailed technical information for qualified service personnel, including system overview, disassembly procedures, troubleshooting, parts lists, and schematics. Below are key sections covering safety precautions, system specifications, service procedures, and component replacement.

1. Safety Precautions 2. System Overview 3. Specifications 4. Disassembly Procedures 5. Troubleshooting Flowcharts 6. Electrical Adjustments 7. Parts List & Exploded Views 8. Schematic Diagrams 9. PCB Layouts 10. Connector Pinouts 11. Test Modes & Diagnostics

Safety Precautions

Before servicing, read all safety instructions. This equipment contains hazardous voltages and components that can retain charge even when unplugged.

Warning	Description
Electrical Shock Hazard	Disconnect AC power before servicing. Use insulated tools.
Hot Surfaces	Allow amplifier heatsinks to cool before handling.
ESD Protection	Use grounded wrist strap when handling PCBs to prevent static damage.
Laser Safety	The DVD module contains a laser diode. Avoid direct exposure.
Component Handling	Replace components only with specified parts to maintain safety.

System Overview

The SA 3-2-1II system consists of three main units: Media Center (DVD/CD receiver), two cube speakers, and Acoustimass bass module.

Media Center: Contains DVD transport, digital amplifier, tuner, and control circuitry.
Cube Speakers: Direct/reflecting speaker arrays for surround sound.
Acoustimass Module: Handles low-frequency reproduction.
Remote Control: RF remote for system operation.

WARNING! Only qualified technicians should perform service. Incorrect reassembly can create safety hazards.

Specifications

Amplifier Power: 200W total system power (50W per channel + 100W bass).
Audio Formats: Dolby Digital, DTS, PCM.
Video Formats: DVD-Video, DVD-R/RW, CD, MP3 CD.
Inputs: Composite video, S-Video, component video, optical digital audio, coaxial digital audio, analog stereo.
Outputs: Speaker terminals, subwoofer line out, composite video, S-Video.
Power Requirements: 120V AC, 60Hz, 180W max.
Dimensions (Media Center): 16.5" W × 3.6" H × 12.8" D.
Weight: 15.4 lbs (Media Center).

Disassembly Procedures

Follow these steps to access internal components. Document screw locations for reassembly.

Media Center Disassembly:

Remove rear panel screws (4x Phillips #2).
Slide top cover rearward and lift off.
Disconnect front panel ribbon cable from main board.
Remove DVD drive mounting screws (6x).
Lift DVD mechanism assembly out carefully.
Main PCB is now accessible for testing/replacement.

CAUTION! Handle flex cables gently to avoid damage.

Troubleshooting Flowcharts

Use these flowcharts to diagnose common system failures.

Symptom	Check	Action
No Power	AC input, fuse F1, standby voltage	Measure +5VSTBY at IC201 pin 3; replace power supply if missing.
No Audio	Speaker connections, amplifier IC	Check output at amplifier IC501 pins; verify input signals.
No Video	Video output settings, cable connections	Test video DAC IC301 outputs; check configuration menu.
DVD Not Reading	Laser assembly, spindle motor	Clean lens with approved cleaner; check motor resistance.
Remote Not Working	Batteries, RF receiver module	Test RF receiver output at CON401; replace if no signal.

Electrical Adjustments

Perform these adjustments with proper test equipment. All measurements at room temperature.

Laser Power Adjustment: Use power meter at test point TP1 on DVD board. Adjust VR101 for 0.45mW.
Audio Output Balance: Apply 1kHz test tone; adjust VR201/VR202 for equal output at speaker terminals.
Bass Level: Adjust VR301 for proper crossover frequency (120Hz ±5Hz).
Power Supply Voltages: Verify +12V, +5V, +3.3V rails within ±5% tolerance.

Tip: Use factory calibration discs for audio/video adjustments.

Parts List & Exploded Views

Genuine Bose parts must be used for replacements. Order using part numbers below.

Part Number	Description	Qty
143775	Main PCB Assembly	1
143776	Power Supply Board	1
143777	DVD Transport Mechanism	1
143778	Front Panel Assembly	1
143779	Laser Pickup Assembly	1
143780	Remote Control (RF)	1
143781	Acoustimass Module Driver	1
143782	Cube Speaker Array	2

Exploded Views: Refer to diagrams on pages 23-28 for assembly relationships.

Schematic Diagrams

Complete schematics for all circuit boards. Diagrams include:

Main System Board (Sheet 1 of 5)
Power Supply (Sheet 2 of 5)
Audio Amplifier Section (Sheet 3 of 5)
DVD Processor & Servo (Sheet 4 of 5)
Front Panel & Display (Sheet 5 of 5)

Note: All schematics are proprietary to Bose. For internal service use only.

PCB Layouts

Top and bottom layer views for all printed circuit boards. Includes component placement and test points.

Main PCB: 6-layer board with ground planes. Note thermal vias near amplifier ICs.
Power Supply Board: High-voltage areas marked with silkscreen.
Front Panel Board: Flexible connector locations highlighted.

CAUTION! Observe ESD precautions when handling bare PCBs.

Connector Pinouts

Pin assignments for all internal connectors.

Connector	Pin	Signal	Voltage
CON101 (Power)	1	AC_IN	120V AC
CON101	2	GND	0V
CON201 (Audio Out)	1	L_CH	Audio
CON201	2	R_CH	Audio
CON301 (DVD)	1-4	DATA[0:3]	3.3V
CON401 (Front Panel)	1	+5V	5V DC
CON401	2	SDA	3.3V
CON401	3	SCL	3.3V

Test Modes & Diagnostics

Access service menu for advanced diagnostics: With unit off, press and hold "1" and "3" on front panel while powering on.

System Test: Runs self-test of all major components.
Laser Test: Checks laser power and focus.
Audio Test: Generates test tones for each channel.
Error Log: Displays last 10 error codes.
Factory Reset: Restores all settings to factory defaults.

Error Codes: E01 = DVD error, E02 = Audio DAC error, E03 = Tuner error, E04 = Memory error.

Service Support: Bose Technical Support: 1-800-999-2673. Service website: bose.service