test to see if subwoofer amp is dead?

[saxon]

Model: 1991 EB with premium audio system (e.g., stock has a subwoofer in back and two stock amps).

I just installed the main amp by-pass and the four door speakers now run fine from the Kenwood head unit.

I also checked to see if the subwoofer was getting power and checked the ground wire to the amp; both are fine. As the only non power related wires into the subwoofer amp originally come directly from the main amp which now has been removed, I cut the sound feed wires into the subwoofer amp and have tried every combination of feed from the head unit RCA jacks imaginable (there are three RCA outputs - I tried all three).

I suppose it could be the head unit but I've had it since new and I suspect that the subwoofer is the more likely culprit.

Is there a way to rig a digital multimeter to test to see if the amp is working?

 

[davesexplorer]

The amp will be putting out A/C current if it's working right. Make sure and check the remote, and power terminals for +12v dc as well.

 

[saxon]

The remote? I'm actually a fairly adept mechanic but not sure what you meant on that (although audio is less familiar territory).

I know that there are two large original wires leading to the subwoofer amp, one is 12v and one is ground and that there is both a black and black with white dashes wire running from the amp to the subwoofer. I will check for AC output tomorrow (thursday) evening. I assume that the AC output is low voltage, higher amp, no? If I remember correctly, the subwoofer amp is 80 or 85 watts. Wondering what level of AC output I should be expecting.

 

[davesexplorer]

When I said the remote wire, I meant the remote turn on wire, or the signal wire depending on how the amp works, it tells the amp when to turn on. I dont know how the factory one works actually, I've always ripped out and bypassed the whole thing... ran all new wiring.

For the power,
Squareroot(Power*Resistance) = Voltage

so.. If the factory sub is 4 ohm ( I cant remember what it actually is? ) then, you'll be looking at -> Squareroot( 85 * 4 ) = 18.43xxx, so when you stick the A/C voltage leads into the outputs of the amp while playing a straight tone, maybe 75% volume or more, you should get around 18VAC. Or if you play music you'll see the output move around... so if the amps working right you'll get some A/C output

 

[saxon]

Cool. Thanks. I'm racing in Spokane this weekend but will check that next week.