Bose PowerShare PS404A

Questions and Answers

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Katherine SextonAug 8, 2025
What to do if my Bose PowerShare PS404A Amplifier has power but no sound?
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  angelaliAug 8, 2025
  If your Bose Amplifier has power but no sound, try these steps: 1. Ensure the input source is on and sending a signal. 2. Check the cable connections between the source and the amplifier. 3. Make sure the OUTPUT ATTENUATION controls are not muted. 4. If a CC-1 zone controller is connected, verify its volume is up. 5. If a contact closure is connected to the MUTE connector, ensure it hasn't been triggered. 6. Confirm loudspeaker taps are correctly set. Additionally, check that the amplifier has adequate ventilation and that the output wiring is correct, as improper ventilation or a short circuit could also cause this issue.
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Michael HolderAug 15, 2025
Why is the sound distorted on my Bose PowerShare PS404A?
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  Amanda SaundersAug 15, 2025
  If your Bose Amplifier's sound is distorted, it could be due to the SIGNAL LED on the front panel being red, which indicates clipping. Reduce the source output level or increase the amplifier sensitivity to 12 dBu. If the input source signal is clean, make sure that the loudspeakers are not overdriven or damaged, and also check the loudspeaker tap setting.
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Melinda WrightAug 22, 2025
How to troubleshoot a Bose PowerShare PS404A with no power?
- E
  erinhermanAug 23, 2025
  If your Bose Amplifier has no power, ensure that the power is turned on. When the power is on, the green LED on the front panel will be visible. Also, make sure the power cord is properly plugged in.
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Megan MillerAug 30, 2025
What to do if Bose Amplifier sound is too low?
- J
  Joel MartinezAug 31, 2025
  If the sound from your Bose Amplifier is low, check the following: * Make sure the audio input source output is at a nominal level. * Check the cable connections from the source to the amplifier. * Ensure the OUTPUT ATTENUATION controls are not set too low. * If a CC-1 zone controller is connected, verify the volume control is turned up. * Confirm that loudspeaker taps are correctly set.

Summary

Safety Information

Warranty Information

Accessories List

Product Description and Key Features

Key Features of PowerShare Amplifiers

Details core features like PowerShare Technology, Load-Independent Outputs, DFL System, etc.

Front and Rear Panel Components Overview

Amplifier Specifications

Power Rating Specifications

Details amplifier power output, maximum power per channel, and gain levels.

Audio Performance Specifications

Specifies frequency response, channel separation, and signal-to-noise ratio.

Audio Input Specifications

Lists input channels, connectors, impedance, level, and sensitivity.

Audio Output Specifications

Details output channels and connectors.

Integrated DSP Specifications

Specifies DSP converters, processing functions, presets, and latency.

Indicators and Controls

Describes front and rear panel indicators and controls.

Electrical Specifications

Covers mains voltage, power consumption, connector, inrush current, and protections.

Physical Specifications

Provides dimensions, weight, and cooling system information.

General Input Notes

Notes about control inputs and software connection via USB/RJ45.

ESDS Device Handling Precautions

Part List Notes

Packaging Part List

Main Part List

Exploded View of Amplifier Components

Electrical Part Lists

Amplifier PCB Assembly Components

Lists resistors, capacitors, inductors, diodes, ICs, and miscellaneous parts for the Amplifier PCB.

SMPS PCB Assembly Components

Lists resistors, capacitors, diodes, transistors, ICs, and miscellaneous parts for the SMPS PCB.

Rear Panel PCB Assembly Components

Lists resistors and capacitors for the Rear Panel PCB Assembly.

DSP PCB Assembly Components

Lists resistors and capacitors for the DSP PCB Assembly.

AmpLink PCB Assembly Components

Lists resistors, capacitors, inductors, diodes, transistors, ICs, and miscellaneous parts for the AmpLink PCB.

EQ Output PCB Assembly Components

Lists capacitors, inductors, and miscellaneous parts for the EQ Output PCB.

Disassembly Procedure

Chassis PCB Locations Diagram

Diagram showing the location of various PCBs within the amplifier chassis.

Critical Safety Warnings

Critical safety warning regarding high voltage within the amplifier.

Top Cover Removal

Instructions to remove the top cover of the amplifier.

Rack Ear Removal

Instructions to remove the amplifier's rack ears.

Rear Bracket Removal

Instructions to remove the rear bracket.

Front Panel Removal

Detailed steps for removing the front panel assembly.

AC Power Switch Removal

Steps to remove the AC power switch.

LED PCB Removal

Instructions to remove the LED PCB.

Front Bezel Removal

Steps to remove the front bezel.

Fan Assembly Removal

Steps to remove the amplifier's fan assembly.

SMPS PCB Removal

Instructions to remove the Switched-Mode Power Supply (SMPS) PCB.

Amplifier PCB Removal

Steps to remove the main amplifier PCB.

AmpLink PCB Removal

Instructions to remove the AmpLink interface PCB.

DSP PCB Removal

Steps to remove the Digital Signal Processor (DSP) PCB.

Rear Panel PCB Removal

Instructions to remove the rear panel PCB.

Rear Panel Output PCB Removal

Steps to remove the rear panel output PCB.

IEC AC Input Jack Removal

Instructions to remove the IEC AC input jack.

Test Procedures

Analog Input Tests

Tests for amplifier performance using analog inputs.

UUT Switch Settings for Analog Tests

Specifies switch settings for the Unit Under Test (UUT).

Gain Test - Low-Z Mode

Measures amplifier gain in Low-Z mode.

Gain Test - Hi-Z 70 V Mode

Measures amplifier gain in Hi-Z 70V mode.

Gain Test - Input Sensitivity (100 V;70 V)

Tests input sensitivity at 100V and 70V settings.

THD+N Test

Measures Total Harmonic Distortion plus Noise (THD+N).

Frequency Response and Noise Test

Tests frequency response and noise levels.

Signal LED Test

Verifies the functionality of the SIGNAL LED indicators.

Limit LED Test

Verifies the functionality of the LIMIT LED indicators.

Crosstalk Test

Measures signal crosstalk between amplifier channels.

AmpLink Functionality Tests

Tests related to the AmpLink digital audio interface.

AmpLink Test Setup

Details the setup for AmpLink functionality tests.

AmpLink Output Level and Frequency Response Test

Tests AmpLink output level and frequency response.

AmpLink THD+N Test

Measures THD+N for AmpLink inputs.

Output Noise Test

Measures the amplifier's output noise level.

Output Gain Control Range Test

Tests the range of the output gain controls.

Input Priority Test

Tests how different inputs affect output level and priority.

Mute Control Test

Verifies the functionality of the mute control.

Auto Standby Test

Tests the auto standby and wake-up functionality.

Hi-Pot Test Procedure

Mandatory Hi-Pot test for shock hazard prevention.

Ground Bond Test Procedure

Ground bond test for chassis safety, performed if ground wire disturbed.

Firmware Update Procedure

Connect the Amplifier

Instructions for connecting the amplifier to a PC for software communication.

Upgrade Amplifier Firmware

Process for upgrading the amplifier's firmware version.

Downgrade Amplifier Firmware

Process for downgrading the amplifier's firmware version.

Troubleshooting Common Issues

LED Fault Indications

Explains the meaning of different LED fault indications.

Troubleshooting: No Power

Troubleshooting steps for when the amplifier does not power on.

Troubleshooting: No Sound

Troubleshooting steps for when there is no audio output.

Troubleshooting: Low Sound

Troubleshooting steps for when the audio output level is too low.

Troubleshooting: Distorted Sound

Troubleshooting steps for when the audio output is distorted.

Troubleshooting: Unnatural Sound

Troubleshooting steps for when the audio sound quality is poor.

Block Diagram of PowerShare Amplifiers

Service Manual Revision History

Bose PowerShare PS404A Specifications

General

Purpose	-
On/off switch	Yes
Product color	Black
Connectivity technology	Wired
Audio output channels	4.0 channels
Peak power per channel	400 W
Signal-to-Noise Ratio (SNR)	100 dB
Total Harmonic Distortion (THD)	0.04 %
Ethernet LAN (RJ-45) ports	1
AC input voltage	100 - 240 V
AC input frequency	50 - 60 Hz
Power consumption (standby)	14 W