Check that an HDMI® cable (if your TV set is Dolby® Digital compatible) or digital optical cable (if you’re connecting to a Dolby® Digital compatible amplifier) has been properly connected between your CM-7500/DVR+ and your Dolby® Digital compatible device (e.g. TV or audio amplifier).
Check whether Dolby® Digital audio is being broadcast on the current program. Press the info button on the remote and check whether the Dolby® Digital icon is present on the info bar. If it is not, then Dolby® Digital audio is not available for the current program.
If the icon is present press CH +/- until you find another channel where the info banner displays the Dolby® Digital icon. If Dolby® Digital audio is output for that channel and works perfectly then the original problem is likely to be caused by the broadcaster.
Check whether the Dolby® Digital Settings on your DVR+ are correct. This is done in the settings menu.
Changing/Checking Audio output settings instructions;
To check or change your HDMI Audio settings;
Press Menu on your remote control. Select Settings>TV and Audio Setup>Digital Audio Setup>HDMI> Choose Stereo Only or Auto Stereo/Surround, and exit.
To check or change the Optical Digital Audio setting;
Press Menu on your remote control. Select Settings>TV and Audio Setup>Digital Audio Setup> Optical Digital Audio> Choose Stereo Only or Multi-Channel.
To check or change "Midnight Mode"
Press Menu on your remote control. Select Settings>TV and Audio Setup>Digital Audio Setup> Midnight Mode> choose On or Off. Reboot the DVR+ by unplugging the power for 10 seconds and plug back in. Note that it may take up to 2 minutes for the reboot process to be completed.
In most cases these steps will resolve your issues.