I've owned a Pioneer VSX-36TX for 2 or 3 years and have been quite
happy with it.

Recently, I acquired an HDTV, and with it a digital cable box from our
local cable service. The cable box has a jack for an optical cable
which will deliver Dolby Digital sound.

When I hook this up to my Pioneer unit, using the "TV/SAT" component
intput, the only sound I get comes from the regular L and R
speakers--nothing from the center or two surround speakers.

The strange thing is that if I re-assign that optical sound input to
"DVD/LD" instead of "TV/SAT", then the problem goes away and I get full
surround sound from all 6 speakers.

Additional info: The display on the front of the receiver is the same
in both cases. It clearly shows that the Dolby Digital signal source
is present, and that all 6 channels are active: L, C, R, LS, RS, and
LFE (subwoofer).

Apparently the receiver's DVD/LD input source can properly output these
signals, but the TV/SAT source cannot. Anybody have any clue why? I
was not aware of any inherent differences in how the receiver processes
these two input sources, and I can find no configuration settings that
would vary between those two sources. As best I can tell, I can assign
any of the 5 digital input jacks to any of the following functions:
DVD/LD, TV/SAT, CD, MD, VCR1, or VCR2.

To confirm the problem, I assigned the Dolby audio output of my DVD
player to each of the various input sources. For the following, it
worked fine and produced full surround sound: DVD/LD, MD, VCR2.
However for TV/SAT, CD, and VCR1 I only got sound from the L and R
speakers. No cables were physically moved during this experiment. The
assignments were all done via the setup menu.

Any suggestions and/or ideas about what's going on would be
appreciated.

Thanks!

Kiteflyer