I am a little embarrassed even asking this question but for the life of me I can't remember how I had my equipment set up before I got my new TV and cable set top box. Should have drawn a diagram. :( Yes, I know it's time to buy a new receiver with HDMI ins/outs.

Here's the equipment I have and I would like to set it up so that I can have my surround sound working.

SA 8300HD cable box
User's Guide (http://www.sciatl.com/products/consumers/userguidepdfs/4003986.pdf) - page 3 shows the back panel


Mitsubishi WD-65833
Back panel (http://www.mitsubishi-tv.com/img/468205/WD-65833%20Dimension%20Drawings.pdf)

Sony STR-DE835
http://i73.photobucket.com/albums/i232/jarhead8286/Miscellaneous/SonySTR-DE835.jpg

Here's the equipment I have and I would like to set it up so that I can have my surround sound working.

SA 8300HD cable box
User's Guide (http://www.sciatl.com/products/consumers/userguidepdfs/4003986.pdf) - page 3 shows the back panel

Looks like you got coaxial (marked as digital audio)and optical digital audio outs. You can run an optical cable from the box to one of the receiver's four, or from the coaxial to the receiver's orange coaxial (next to the optical.) Either will work just as well, as they transmit the same surround sound signals (just using different methods.) I'd personally go for optical since you have four available and you might get some component later that only uses coaxial, but that's minor.

Then HDMI direct to the TV. I have this setup with mine (coaxial from cable box to receiver, HDMI from box to TV. Works great.

I currently have optical audio out (TOSLINK) from the cable box going into the receiver's optical TV/SAT. Then I have HDMI cable going from the cable box into the TV.
When I turn on the receiver, I do get Dolby sound, but not 5.1.

Dumb question, but are the shows you're watching actually putting out 5.1? Your HD channels might, if the show on has a 5.1 soundtrack (usually primetime.) But the vast majority will be some form of mono or stereo.

Prologic II if available on your receiver can expand it to a matrixed surround sound. If the show isn't in 5.1, there's not much else you can do.

I currently have optical audio out (TOSLINK) from the cable box going into the receiver's optical TV/SAT. Then I have HDMI cable going from the cable box into the TV.
When I turn on the receiver, I do get Dolby sound, but not 5.1.
Most TV channels do not have 5.1 encoding. You'll find it on many HD channels, although not all programs in HD have 5.1 sound tracks. Local news, for example, is only mixed in stereo. Even MTV-HD has lots of stereo programs that are encoded with PLII, not discrete 5.1.

The best way to check your equipment is to tune in a primetime HD network show that you know has DD 5.1 audio. Use the automatic setting for the TV/SAT optical input on your receiver. DD 5.1 should be displayed on your receiver.

I am not familiar with your equipment. Some components use the HDMI handshake to control the optical audio output as well. So, if your TV asks for a two channel input over HDMI, then the optical feed to your receiver may get downmixed too. You may want to unplug the HDMI feed to the TV, power the cable box off and back on, and see if that makes a difference. There may also be a setting on the cable box as well.

If you have a DVD player handy, you can try running optical audio from the player to the TV/SAT input on your receiver. If you play a DD 5.1 track on a movie and it shows up as 5.1 on your receiver, you'll know the AVR works properly.

Dumb question, but are the shows you're watching actually putting out 5.1? Not a dumb question at all. I tuned into HBO-HD and know that most of their movies are in 5.1. I will check tonight.

Not a dumb question at all. I tuned into HBO-HD and know that most of their movies are in 5.1. I will check tonight.
Actually, many are not. HBO uses the same audio treatment for both SD and HD. It doesn't make much sense, but that's the way it is.

So it wasn't the problem with the hook up after all - the problem was the "Audio: Digital Out" on the cable box (menu setting) was set to HDMI instead of Dolby Digital. I recall playing around with it since I couldn't control the volume using the cable box (still can't).

So it wasn't the problem with the hook up after all - the problem was the "Audio: Digital Out" on the cable box (menu setting) was set to HDMI instead of Dolby Digital. I recall playing around with it since I couldn't control the volume using the cable box (still can't).

Taking this thread in a slightly different direction... I hooked up my TV with HDMI cable from cable box to TV. In the Scientific Atlanta's 8300HD menu setting, there is a setting for Audio: Digital Out. The options are Dolby Digital and HDMI. In order to be able to hear 5.1 through my receiver, I have to set it to Dolby Digital. If this setting is set to Dolby Digital and I am not using my receiver for audio, the audio on the TV does not work and I have to change the setting to HDMI. Is this a normal behavior?

edit:
I guess I am not the only one with this problem:

http://www.avsforum.com/avs-vb/showpost.php?p=6232298&postcount=7

Many TVs have an analog stereo pair associated with at least one HDMI input. It's designed to be used with a DVI source which doesn't carry audio, of course. The analog stereo output from your cable box is likely active regardless of the digital audio setting. Perhaps that's a solution for you.