Resoldering loose wires. If you hear intermittent sound or static on headphones plugged into a home stereo unit, it may mean a poorly connected wire in the headphone’s plug or in its speakers.
Put on the headphones and gently wiggle the cord where it enters the speaker sections and the plug. Static or intermittent sound at any of these locations may indicate that resoldering is needed. Hold the plug’s screw cap and unscrew its prong. (If the plug can’t be disassembled, cut it off and replace it with one that can be.) Unscrew or pry off the speaker covers.
Check all connections of the wire leads. Even though only one may be bad, resolder all of them to keep the wire lengths uniform.
Snip off each wire 1/2 inch from its connection. Using a pencil-type soldering gun, melt the solder that holds the wires to the prong or speaker and discard them. Strip 1/4 inch of the insulation from each wire, then reconnect them with fresh solder.
If no sound reaches your ears, clip a jumper wire to the widest band on the plug’s prong and to the bottom rim of an AA battery. Place the tip of the battery on the middle band of the plug (1). If you hear static in one speaker, it’s working. Test the other speaker by touching the tip of the battery to the prong tip (2). If there’s no static, that speaker is dead and must be professionally repaired.