Car Stereos: Bose amplifier, using a multimeter, bose amp

Question
How do you test your bose amp to see if it works?

Answer
Hi Dora,

It really depends on the vehicle, because there are many different types of Bose systems and they're wired in different ways.  Generally, it would be tough to test an amplifier, inside or outside the vehicle, unless you had a wiring diagram for the plugs.  

You can test a Bose amplifier using a multimeter with an AC voltage function.  It helps if the meter has a moving display, and not just numbers; you could use an analog meter with a needle, or a digital meter that has a bar graph feature.

Basically, all audio signals are carried through wires as AC.  That means you can test an amplifier by looking for AC voltage on the output wires.  As the volume of the audio signal increases, the AC voltage increases.  If you have an analog meter or a digital meter with a bar graph, you can watch the needle or bar graph display bounce in time with the music.  

First, use the DC voltage function of the meter to verify that the amplifier has power.  Sometimes, there's also a "turn-on" wire that carries a voltage to tell the amplifier when to turn on and off.  (Newer Bose amps in some vehicles are activated through a data signal; in this case, you'd need to have the amplifier connected to a working factory radio in order to test it).  Once you've confirmed that the amp is powered and turned on, then you can turn on the music and test for AC voltage on the output wires.  If there's no output voltage, then you can move to the audio input wires and test for voltage there.  If you don't find an AC signal on the input wires, then there may be a problem with the source unit: ie, the factory radio.  If there's AC present on the inputs, but nothing on the outputs, then you probably have a bad amp.  And if there's AC present on the outputs, then the amp is good.

Hope this helps!

Brian