Trace transistor output

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I need to find speaker outputs for a car amp that is missing harness. This is an oppourtunity for me to learn some basics. I have 4 output transistors which is the speaker positive output? P or N? which pin do I follow? Are the pins for the speaker lead directly in series with speaker leads?
 
The speaker connector is top center. I want to find two pairs of speaker leads. It is not apparent with ohmeter.
 

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If your meters black probe is connected to the center tap connection of the secondary of the power supply < true common ground of the audio side >, then any ground wire in that plug should read zero ohms.
Unless you have a open trace on the amp somewhere like on the bottom of the board.
Ground for the speaker will also be the common ground for the secondary side of the bi-polar power supply feeding the amp. All the rest of the hot speaker wires will read like diodes since they are reading thru the circuitry back to ground, so you will see diode like readings on the hot speaker terminals and zero ohms on the ground terminals.

Plus Alpine use to mark their connections on the bottom of their circuit boards but you will have to completely remove the board to look for those possible markings...hope this helps some...
 
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