Bought a used Denon back 5 months ago . The AVR-X3700h and recently the sound went out all of the sudden. No problem with video. I could hear the volume change at the end of the volume scale (faint clicks ) and noise appear in the speakers. I tried a bunch of things including reverting the firmware back to original, resetting all settings....cables . Nothing really helped.
I noticed that when tugging on the output jacks the sound would come back. So i fiddled with it some and seemed to work. I did the Audesey calibration since firmware was reflashed and during the calibration i noticed that some of the channels where not outputting at all ( Surround left and Hight right.) . I thought it might be bad solder joints so i took the unit apart. About 100 screws later I had the output board out.
I took the board to my shop and looked it over with a microscope. I didn't notice any bad solder joints but redid the solder on all of the speaker terminals and relays anyway. I also touched up all the voltage regulators that are on the same bottom board. After that I used contact cleaner on all the contacts that go between the boards.
The Top board that had HDMI ports and DSPs connects to a backboard that has the DACs and op amps. This back board also has the most connectors as it connects all the other boards together. I think the cause of no sound was oxidized or stressed connections between boards. Flexing the speaker board will slightly move the connectors and sometimes restores connections for a while.
After all was back together I had sound on all channels. I was able to finish calibration without issues and moving the banana outputs didn't impact anything anymore.
Most likely there are bad connections and taking the unit apart (input/output board assembly ) using contact cleaner and putting it all back together would have solved it.
I took about 3 hours total after making the decision to take it apart.
If I would have omitted the soldering it would have taken 1 hour as there no need to take out the bottom board. All connectors can be cleaned without taking that board out.
Service manual found here in case someone needs it.
Maciej
I noticed that when tugging on the output jacks the sound would come back. So i fiddled with it some and seemed to work. I did the Audesey calibration since firmware was reflashed and during the calibration i noticed that some of the channels where not outputting at all ( Surround left and Hight right.) . I thought it might be bad solder joints so i took the unit apart. About 100 screws later I had the output board out.
I took the board to my shop and looked it over with a microscope. I didn't notice any bad solder joints but redid the solder on all of the speaker terminals and relays anyway. I also touched up all the voltage regulators that are on the same bottom board. After that I used contact cleaner on all the contacts that go between the boards.
The Top board that had HDMI ports and DSPs connects to a backboard that has the DACs and op amps. This back board also has the most connectors as it connects all the other boards together. I think the cause of no sound was oxidized or stressed connections between boards. Flexing the speaker board will slightly move the connectors and sometimes restores connections for a while.
After all was back together I had sound on all channels. I was able to finish calibration without issues and moving the banana outputs didn't impact anything anymore.
Most likely there are bad connections and taking the unit apart (input/output board assembly ) using contact cleaner and putting it all back together would have solved it.
I took about 3 hours total after making the decision to take it apart.
If I would have omitted the soldering it would have taken 1 hour as there no need to take out the bottom board. All connectors can be cleaned without taking that board out.
Service manual found here in case someone needs it.
Maciej
