Fix: computer speaker sets

Found 2 identical speaker sets in the e-waste. (EP-691H Multi-Media Amplified Speaker System)

Inital test: One speaker set works perfectly fine. The right speaker on the second set doesn't work and the left speaker works (loudly) only when the volume dial is turned to max.

Opened up both sets to reveal what appeared to be the same thing. There were no bulging capacitors on either board. Tested the bad speaker set's right speaker on the good set, and it turned out that the right speaker itself was fine.

Ran my fingers along the bottom of the circuit board, causing the bad left speaker to emit funny cool noises like R2D2. (aka circuit bending) Interestingly, circuit bending the boards of both speaker sets caused similar noises to emit. Therefore I figured that the left speaker was most likely working, so redirected my attention to the board itself.

After circuit bending and playing with the volume dial for over an hour in frustration and fun, I finally decided to pull out my multimeter to test the potentiometer.

Observed:
Pot controls left and right speakers separately (separate circuit leads)

When vol dial(pot) turned from min to max,
Good set's pot: Both leads go from 9.5kohm up to ~13kohm for a bit then linearly back down to about 4 ohms

Bad set's pot: Top lead: 12kohm up to 50kohm then drops SHARPLY to a few ohms, near "max volume"  Bottom lead stays at ~38Mohm.




Results:
- The pots from the two sets behave very differently.
- Resistance and Volume are have an inverse relationship.
- The behaviour of the bad pot's top and bottom leads corresponds exactly to the results of the Initial Test.
Top lead's sharp drop causes left speaker to suddenly have max sound near max volume and stay mute otherwise. Bottom lead stays at a constant high resistance(Mohms), causing no sound on the right speaker, regardless of pot position.

As expected, shorting the top and bottom leads caused max sound on left and right speakers regardless of pot position.



Conclusion
bad potentiometer, need a 9kohm to 4ohm resistor to fix.