I have the coaxial cable out from my cable box plugged "in" to the antenna input on the back of the unit, but after running the auto-preset sequence for my channels, nothing comes up.
Anyone know what I can do to rectify this?
With coax from a cable box as the Mag's coax input, your Mag is a "slave" to the box... the box has to tune channels for the Mag, and the Mag has to be set on ch. 3 or 4, whichever your box's manual says to use. With this setup, the Mag can't scan and tune any channels except the one the box is set to.
IF ALL your channels are scrambled, then this is the way you'll have to connect since the Mag won't be able to tune any channels by itself. If you KNOW that ALL you channels are scrambled, keep the setup you have now, where you'll only be able to record the channel you set the box to, or the one you can "auto-set" the box to with a REC (record) from the Guide or some other auto-tune feature of your box.
IF you DON'T know if you have any unscrambled channels, connect the incoming cable coax to the Mag 1st, then coax out to the box. Then a "line connection" from the Mag to your TV (HDMI, Component RGB, S-Video or Composite YWR RCA), which will send internal Mag stuff to the TV (menus, channels, recorded HDD titles, DVDs). Nothing internal goes thru the Mag's coax circuit. It's only a signal passthrough for downstream components like your box and/or TV.
After connecting the Mag 1st on the coax, do an Auto Channel Preset > Cable (Analog/Digital) and see how many channels the Mag tunes. If you do get some channels in the Mag, you'll be able to record them directly with the Mag. If NO unscrambled channels, go back to the way you were originall set up.
If needed, see this help file for a Connection sketch and detailed instructions.
If you can keep the Mag 1st on the coax and record some channels that way, you'll need a line connections from the box back to the Mag for recording scrambled channels the Mag can't tune, as shown in that Connections help file. For recording those scrambled channels, go to the help file on Recording for info on how to record from the cable box (STB).
Hopefully, this will get you started?