We have a new Cisco/Scientific Atlanta Explorer 4652HDC cable box/DVR, and am searching for the discrete IR codes that control power on/off for the unit.

Thanks in advance for your help!

Brian

AFAIK there are no discrete On/Off Codes for these Cable Boxes.  They are TOAD only.

Most SA boxes have the ability to power on with power and numeric, it should be in the second page of the settings where you can change this from power only.
By using this you can create macros that will turn the box on and off reliably.
Of course the model number you are using might be one that does not have this feature, I don't know as I have not dealt with every Cisco / SA box. I have also heard that this feature is not always available everywhere.
Up here in Toronto I have yet to find a box that I could not turn on and off this way.

The cable provider here in SoCal (Cox Communications) has disabled this in their software versions loaded on the box.  Even if you turn the box off, it still is on just not outputting any image to the tv, other than the Cable box is off press power to turn on, and the front display defaults to time.

I heard that in some areas of the US cable co's had disabled this feature. Makes you shake your head and wonder why.

"Even if you turn the box off, it still is on just not outputting any image to the tv, "

Does this mean that the power outlet on the back never turns off either? (or does this model not have one?)

If there IS a power outlet, I think the ability to have it turn on/off is standard regardless of software. I'd expect the 4600 series to have one.

And with a power outlet on the back, that you can turn on / off with the box you do have a solution (depending on which remote control system you are using).

I just leave the damn thing's on anyway.  Even if you turn them off, there is a message on the screen that you need to press power to view tv.  Most of the phone calls I get are why can I not change channels, I have to tell the client to manually unplug the power cable, wait 1 minute, and then plug the damn thing back in.  This is the weakest link IMHO of any system.  DirecTV and Dish are no better in this regard.