Fooey. I fool around inside of live, low voltage equipment (such as satellite receivers) all the time, and I've never zapped myself even once. P. Smith is probably right that you can locate 117VAC pretty easily; that should be the highest voltage anywhere inside your Dish Network receivers. But usually the 117V is fully insulated all the way into the transformer.
Switching power supplies... That's a possibility for higher voltages depending upon how it's engineered, and what it's doing. Florescent light bulbs need high voltage, but satellite receivers do not. Anyhow, I think these power supplies are typically entirely enclosed inside of their own metal box, similar to a PC power supply. So taking the lid off a 722 would still not expose anybody to more than 25V or so. You would not feel anything, (assuming you have dry skin).
But as bebop says, you don't want objects falling into the receiver either, since (safety aside) the receiver could be damaged. What I thought you (bebop) meant was high voltage, e.g. such as exists inside CRT TVs. Just because a receiver is associated with television, it does not follow that there is high voltage inside the receiver itself. The old CRT color TVs used to generate not 25V but 25,000V. That's high voltage! You could definitely get zapped, if not X-rayed, by that old tech stuff, whether or not your skin is dry.
I have never disassembled an LCD TV. Anybody know what kind of voltages are inside? Edit: most have florescent backlights, so I imagine they too have 1000's of V inside.