There Is Severe Humming Or Noise - Sony STR-DH770 Manual

No sound or only a very low level of sound is heard,
no matter which device is selected.
Check that all connecting cables are inserted to their input/output jacks on the receiver,
speakers and the devices.
Check that the receiver and all devices are turned on.
Check that MASTER VOLUME on the receiver is not set to [VOL MIN].
Check that SPEAKERS on the receiver is not set to [SPK OFF].
Check that headphones are not connected to the receiver.
Press to cancel the muting function.
Try pressing the input button on the remote control or turning INPUT SELECTOR on the
receiver to select the device of your choice.
If you want to listen to sound from the TV speaker, press AMP MENU, then set [<HDMI>] -
[AUDIO OUT] to [TV+AMP] on the display panel. If you cannot play multi-channel audio
source, set to [AMP]. However, the sound will not be output through the TV speaker.
Sound may be interrupted when the sampling frequency, number of channels or audio
format of audio output signals from the playback device is switched.
[144] Troubleshooting Sound

There is severe humming or noise.

Check that the speakers and device are connected securely.
Check that the connecting cables are not near a transformer or motor, and are at least 3
meters (10 feet) away from a TV set or fluorescent light.
Move your audio device away from the TV.
The plugs and jacks are dirty. Wipe them with a cloth slightly moistened with alcohol.
[145] Troubleshooting Sound
No sound or only a very low level of sound is heard
from specific speakers.
Connect a pair of headphones to the PHONES jack to verify that sound is output from the
headphones. If only one channel is output from the headphones, the device may not be
connected to the receiver correctly. Check that all of the cables are fully inserted into the
jacks on both the receiver and the device.
If both channels are output from the headphones, the front speaker may not be connected
to the receiver correctly. Check the connection of the front speaker that is not outputting
any sound.
Make sure you have connected to both the L and R jacks of an analog device, as analog
devices require both L and R jack connections. Use an audio cable (not supplied).
Adjust the speaker level.
Check that the speaker settings are appropriate for the setup using Auto Calibration in
[Easy Setup] from the home menu or [<SPEAKER>] - [SP PATTERN] on the display panel.
Then check that sound is output from each speaker correctly using [<LEVEL>] - [TEST
TONE].
Some discs have no Dolby Digital Surround EX information. In this case, sound may not be
output from some speakers.
Check that the subwoofer is connected correctly and securely.
Make sure you have turned on your subwoofer.
Depending on the selected sound field, sound may not be available from the subwoofer.
Depending on the source, there may be no sound from the subwoofer when all speakers
are set to [LARGE] and [NEO6.CINEMA] or [NEO6.MUSIC] is selected.