Although I am not familiar with this specific speaker, I might suggest an
approach that, perhaps, could help. If the speaker terminals are directly
accessible (I presume that they may not be, by your approach), simply test resistance from positive speaker terminal to connector. A low or zero
ohms resistance shows a direct connection. Presuming that the terminals
of the speaker are not directly available, you might use this alternative
approach (I am assuming that you have identified the negative speaker
terminal input, as I believe you indicated).
Obtain/ make a simple audio generator - a LM555 timer chip would do fine.
Desired frequency about 100 Hz (not critical). The 555 circuit output pin
is connected to the speaker ground via a 1K resistor (might need to decrease to 100 ohm value if you can't hear any speaker output - it will be
clearer in a moment). The 555 circuit positive voltage supply is connected to a wire for probing the input connector pins one at a time.
The pin which gives loudest hum should be the one you want. Please note: the 555 circuit built is an astable multivibrator circuit. If you do a search on Google for 'LM555 circuits', you will find many examples.
Positive power supply should be 10 to 12 volts.
Best Of Luck!
StanleySMD@netscape.net
