To get to diagnostic screen hold down INFO button on remote for about 3 seconds.
Use CH +/- buttons to scroll up and down
Use ENTER to select menu item
Use LAST button to back up
Select TUNER STATUS for QAM chan frequency, Signal power level, and SNR of channel box is currently tuned to.
Select CURRENT CHAN STATUS for Virtual channel number, QAM freq, Modulation, and program number.
Select VITUAL CHANNEL MAP for list of all virtual channels, screen channel name, CDS ref which is chan frequency, and program number.