edit I am not looking for a repair, I am trying to learn about what could cause the strange behavior simply for the sake of science.

Ok so I have an old Yamaha sound system that is mostly broken (over 20 years old) the only thing that remains working is the speakers. They use the red/black clamp terminals (2 wires per speaker) with exposed end wires that go to the system. The input is coming from my PC which has a 3.5mm (motherboard) to red/white cable (sound system).

The odd behavior is that sometimes, usually when something is jostled or my cat jumps on one of the speakers or even getting up from my chair, the sound becomes very weak and favors one speaker (not always the same speaker). Now I don't really know the cause of this, but the part that confuses me is how I am able to fix it.

I open up the Playback properties and go to the properties of my device, then to the Advanced tab and click 'Test'. This plays a melody first in one speaker, and then in the other. Then after that the sound is at full power again and coming from both speakers!

Seems odd to me, especially with the randomness at which it goes all weak and lopsided, but the fact that just running a sound test restores it makes it even stranger. Any idea what is going on here?

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closed as off-topic by tcrosley, Olin Lathrop, Ricardo, Leon Heller, Matt Young Mar 24 '15 at 18:53

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Olin Lathrop, Ricardo, Leon Heller, Matt Young
If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Questions on the use or repair of consumer electronics is off-topic in this forum. \$\endgroup\$ – tcrosley Mar 24 '15 at 15:33
  • \$\begingroup\$ @tcrosley I'm not trying to repair it I am looking for the science behind what would cause the strange electrical behavior because it seems so odd to me. \$\endgroup\$ – MetaGuru Mar 24 '15 at 15:36
  • \$\begingroup\$ Still not a question re electrical design. \$\endgroup\$ – tcrosley Mar 24 '15 at 15:40
  • \$\begingroup\$ I suspect it's a loose connection somewhere in the wiring, and it's not the sound test causing it at all. Either that or dried out electrolytic capacitors. \$\endgroup\$ – pjc50 Mar 24 '15 at 15:40
  • 1
    \$\begingroup\$ How is this a electronics problem? Seems like a software or user-level issue. \$\endgroup\$ – Olin Lathrop Mar 24 '15 at 15:55

This behavior is typical of an oxidized connection. The reason the Windows test sound fixes the problem is that it is louder than the normal audio you are listening to. The louder level breaks down the oxide layer.

To track down the bad connection, wiggle or move anything mechanical that is in the audio path. This includes the 3.5mm plug coming from the computer as well as any selector switches, volume controls, tone controls on the amplifier. Wiggle the Source / Tape switch if there is one.

I'm actually going to put my money on the 3.5mm plug coming from the computer.

But it really could be anything.

  • \$\begingroup\$ thanks for taking this seriously, I figured it was something "pushing through" like that but didn't know exactly what it meant, this makes sense though \$\endgroup\$ – MetaGuru Mar 25 '15 at 14:31

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