So, my parents went away on vacation and asked me to stay over at their house while they're away. Firing up the system in the basement, I discover DD 3.1 surround ... that is, center, surround left, surround right, and bass. Strange that my dad would have disabled the mains, but nothing I can't fix.
A check of the cables turns up nothing disconnected, all connections are solid. Ok, maybe it's some strange setting on the receiver (a Yamaha RX-V863). I switch it to stereo -- no audio (except for some bleed out of the center and surrounds and some occasional low sounds out of the sub). So I go into the receiver's manual setup, choose equalizer so that I can set all levels manually, and generate a test tone. With all EQ levels set to 0 db I get noise out of the center, both surrounds, and the sub, and nothing out of either main channel. So I text my dad to ask "how long have TV commercials been coming in with bass only, no other sound?" He responds "it just started happening yesterday."
Any ideas what is going on? Since I'm at his place, I don't have access to any other speakers to see if it's a speaker issue. I haven't had a chance to visit the hardware store and buy a voltmeter to determine if the main speaker terminals are hot, but that's on my list. Since I'm not familiar with this receiver, what I'm really wondering is whether anyone knows if there is a setting somewhere buried in the menus that would defeat the mains and leave all other speakers as they are? Also, if this is a receiver malfunction, what could cause power to the mains to fail suddenly without affecting anything else?