How do you tell if there's a soldering problem with your speaker or A/V receiver?

UUUUUUUUUUUGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHH!
Last week my old receiver died. Just stopped working mid song. Ran out and bought a Panasonic to replace my Yamaha, sound quibbles aside the thing worked. (It should being brand new.) Now I wake up and my left speaker is shorting in and out. I rework my cabling to make sure that's not it. Then I run the sound through my headphone jack to make sure it's not my external DAC creating problems. Then I swap speaker cables, the left to right and vice versa. Same speaker creating problems. If I turn the sound up louder the shorting stops but it still buzzes. Crud it's been a few weeks on troubleshooting. I just wanna listen to some music!
Is it the speakers or the brand new receiver?
Help me if you can I'm feeling down and I do appreciate the forums being 'round.

 

I think you've done a good job of determining that its the speaker, could be the internal wiring/components, could even be the driver.

 

Dry solder joints will manifest as an intermittent fault - it worked before, then it didn't, now it does... They are most common in amps, where the heat can affect them (eg. the unit works when it's first turned on, then when it warms up it fails due to heat expansion of the dry joint. Then when you turn it off, it cools and will work when it turns on until it warms up, then the cycle repeats).

 

This seems the most likely since what you describe is what seems to be happening. I just turned it on for the morning and am having no problems form the speakers. However what has me suspicious of the speaker is that when I switched sides of the speaker in the receiver the same speaker was problematic. However I also realized I just switched sides to test without swapping out the actual cables. So perhaps the problem is in the cabling but I can't see how or why. I've no problem returning the receiver but I loathe the idea of sending my speakers cross country to get tested, especially if nothing is wrong.

 

You've done part one (switching the cables at the receiver end) and the problem didn't move. You've proven the receiver works. So now do part two (switching the cables at the speaker end, leaving the receiver end where they are). They you'll know if it's the speaker or the cables.

 

I recently had an intermittent problem with my speaker, it turned out the screw holding the wire in the banana plug had become loose. I checked the other plugs, they were loose as well. And I though I had bought quality plugs (not in the wbt league though).