(This happened a few weeks ago, but I am just now getting to writing about it). The other day, my son was complaining that the volume on the TV would go up and down. To be honest, I didn’t pay a lot of attention to his report, I told him that the broadcasters often increased the volume of commercials. Then, that night, the rest of the family started complaining about it. I listened, and sure enough, it was fluctuating from normal to barely audible (with not much in-between).
The TV is hooked up to the stereo, so the first step of troubleshooting was to verify that the wires to each of the two speakers weren’t loose. Check. Next step was to see if the problem was occurring with just one device. At first I thought it was just the TV, and I spent time hooking our portable TV into the system, but that reproduced the problem, too.
Then I became briefly convinced that it was the VCR—because the problem occurred with TV and VCR, but didn’t seem to occur with radio. That was annoying, because the VCR was just a year old. But after more listening, it became apparent that the problem manifested on all playback devices. So I concluded the stereo receiver—also bought just one year ago—was the problem.
Thus, the following weekend, I went to Best Buy to purchase a replacement. I went through all the pain of moving my stereo cabinet, sorting through the horrible tangle of wires back there to unhook everything, remove the receiver (the hub, of course, with everything hooked into it), replace it with the new receiver, and proceed to hook everything back up. Fortunately, the rest of the family was out doing errands, so I was left to my struggles in peace.
I then started to review the manual for the new stereo—something I had never gotten around to, despite good intentions, with the previous one—and started experimenting with the different surround sound options (theater, stadium, etc.). Imagine my astonishment to find, as I switched to a surround sound mode, that the muffled volume problem suddenly re-appeared, now with the new receiver! Almost as suddenly, the diagnosis formed itself in my mind: someone had accidentally pressed a button on the remote to invoke one of the surround sound options! Since I didn’t have front speakers hooked up (see below PS), that resulted in the portion of the audio intended for the front speakers—which varies during the audio track—to be lost!
So I performed the receiver swap, again, in reverse, and boxed up the new receiver for return. Of course, it was dumb luck that I diagnosed the problem before I had disposed of the old receiver. I felt a little sheepish, but on the other hand, how was I to know? Just another example of the burden required for maintaining a mental model of how systems work. Murphy lives!
PS It would be nice if every appliance of any complexity had a “safe mode” (like modern versions of Windows and other operating systems), that would operate the appliance at a “lowest common denominator” configuration, to aid troubleshooting and recovery.
PPS, I had planned on hooking up auxiliary front speakers when I set up the stereo a year ago (in which case, I would never have concluded the receiver was defective), but I hadn’t yet found the box from our move. Months went by, and still those were just about the only item I couldn’t find. I already had several pairs of aux speakers, so I resisted buying more. Anyway, after the above incident, I bit the bullet and bought inexpensive aux speakers. Of course, it was only a few weeks after that the the missing speakers turned up! More Murphy!
7:32:30 AM 
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