Denon AVR-688 User Manual (English)

Other manuals for Denon AVR-688

Owner's Manual128 pages

Specifications2 pages

Questions and Answers:

W
Walter LeeAug 21, 2025
Why is there no sound coming from my Denon Stereo Receiver speakers?
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  Priscilla BerryAug 21, 2025
  Several factors could be causing this issue: * Faulty connections: Check the connections with the input devices and the speaker cables. * Incorrect input source: Ensure the device you want to play and the set input source match; select an appropriate input source. * Low master volume: Adjust the master volume to an appropriate level. * Mute mode is on: Cancel the mute mode. * Headphones are connected: Disconnect the headphones. * No digital signals are being input: Select an input source for which the digital input setting has been made. * Mismatch between digital inputs and input modes: Set the input mode.
D
Darin OlsonAug 22, 2025
Why is there no sound coming from the center speaker of my Denon Stereo Receiver?
- S
  Sheila HopkinsAug 22, 2025
  If you're not hearing sound from the center speaker, and you are playing a monaural source (TV, AM radio broadcast, etc.) in the “STANDARD” (Dolby/ DTS Surround) mode, ensure the mode is set to something other than “STANDARD” (Dolby/ DTS Surround).
J
Jeanette PotterAug 25, 2025
Why is there no sound coming from the surround speakers on my Denon Stereo Receiver?
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  James RiveraAug 25, 2025
  If you're not getting sound from your surround speakers, it might be because the surround mode is set to “STEREO” or “DIRECT.” Set to a surround playback mode.
A
Austin ChenAug 26, 2025
Why is there no sound coming from the surround back speaker on my Denon Stereo Receiver?
- C
  Charles BlakeAug 27, 2025
  If you're not hearing sound from the surround back speaker, check these settings: * Ensure the surround back speaker’s power amplifier is correctly assigned to the appropriate channel. * Verify the Surround back speaker setting is something other than “None.” * Confirm that the surround mode is set to a mode for 6.1- or 7.1-channel playback.
A
Anthony HendrixAug 27, 2025
Why is there no sound coming from the subwoofer of my Denon Stereo Receiver?
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  Patrick FrazierAug 27, 2025
  If your subwoofer isn't producing sound, try the following: * Make sure the subwoofer’s power is turned on. * Check that the “Subwoofer” setting at “Speaker Setup” is set to “Yes.” * Verify the subwoofer is properly connected. * Adjust the subwoofer’s volume to an appropriate level.
M
Mark RobbinsAug 29, 2025
Why are HDMI audio signals not output from speakers on my Denon Stereo Receiver?
- W
  Walter McmahonAug 29, 2025
  The audio signal input to the HDMI input connector cannot be played on the AVR-688. Input the audio signal to the digital audio input connector or analog audio input connector.
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Jonathan MortonAug 31, 2025
What to do if my Denon Stereo Receiver power turns off suddenly and the power indicator flashes red?
- C
  Connor GriffinAug 31, 2025
  This usually indicates the protection circuit has been activated. This can happen due to several reasons: * The internal temperature is too high: Turn off the power, wait for the unit to fully cool down, and then turn it back on. * Speaker wires are touching: Unplug the power cord, twist the core wires tightly or terminate the speaker cables, and then reconnect them. * Incorrect speaker impedance: Use speakers with the specified impedance. * The set is damaged: Turn off the power and contact a DENON service center.
D
Dr. Michael MarshallSep 1, 2025
What to do if my Denon Stereo Receiver is not working properly when using the remote control?
- C
  Crystal TuckerSep 1, 2025
  If your remote control isn't working as expected, here are a few things to check: * Worn batteries: Replace with new batteries. * Out of range: Operate within the specified range. * Obstacle: Remove any obstacle between the main unit and the remote control unit. * Incorrect battery direction: Insert the batteries in the proper direction, following the polarity marks in the battery compartment. * Strong light interference: Move the set to a place in which the remote control sensor will not be exposed to strong light. * Remote ID mismatch: Set “Remote ID” for the main unit to “1.”
S
scarlsonSep 3, 2025
Why does my Denon Stereo Receiver have no picture?
- J
  Joe JohnsonSep 3, 2025
  If you're not seeing a picture, consider these possibilities: * Faulty connections: Check the connections between the AVR-688 and monitor. * Incorrect monitor input setting: Set properly. * Incorrect signal conversion: High definition (1080i/720p) and progressive (480p/576p) video signals are not down-converted. Set the player to interlace (480i/576i) signals if using component input connectors with video (yellow) or S-Video output connectors.
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jnixonSep 5, 2025
Why is there no picture with HDMI connections on my Denon Stereo Receiver?
- S
  Steven WalkerSep 5, 2025
  If you're experiencing picture issues with HDMI, try these solutions: * Check the connections to the HDMI connectors. * Verify the HDMI input setting. * Ensure the HDMI format of the player and monitor match.

Denon AVR-688 Specifications

General

HDMI Outputs	1
Total Harmonic Distortion	0.08 %
Input Sensitivity	200 mV
Tuner Bands	AM/FM
HDMI Switching	Yes
Power Output (per channel)	90 Watt
Audio Formats Supported	Dolby Digital
Response Bandwidth	10Hz - 100kHz
Input Impedance	47 kOhm
Frequency Response	10Hz - 100kHz
Inputs	HDMI
Outputs	HDMI