Fixing Headphones = Headache

I attempt to fix a couple pairs of broken Sony MDR-7506 headphones yesterday. Both had one driver out, no sound or distorted weak signal in one ear. I tested continuity from the plug to the contacts on the first driver and determined one pair to have a bad plug, so I replaced it. In the other pair, I faulted the driver and replaced it with a working one from a third pair.

Now both pairs have the same issue. The repaired side is weaker than the other, and the seperation is no longer there. When panning a signal hard left to hard right it is apparent in the headphones, but never goes completely off in the other side.

What gives?

[quote author="skipwave"].....and the seperation is no longer there...[/quote]

This happens usually if the common ground is missing.
Check that the drivers are connected in phase also.

Regards,
Milan