Amp powers up but there’s no sound

Just bought a brand new MTX MXA4002 off of ebay, got it hooked up, but the sub doesn't fire up.  The amps red light is on, which I assume is the power light, but nothing happens.  I tried it on another speaker, and nothing there either.  I hooked up a different amp and the sub fired up fine, so I know it has to do with the amp.  Both the fuses are fine, All the fuses in the system are fine.  I tried other sets of RCA's, which all got sound to a different amp, but that didn't work either.  I am completely stumped here, any suggestions??? 

Well from the sound of it, it looks like you covered all the bases.  You checked the subs with another amp and they work fine, so it's not the subs.  You've checked power, ground, remote and rca's when you swapped the other amp so, it's not that.  I'd check the gain on the amp and if it's properly set then, it looks like you got a messed up amp. 

That's what I was thinking too.  I've moved the gain down and up, and no response.  So, I'm guessing my amp is messed up.  What's weird is that it came with a sheet showing its power output.  Is there something I might have done to cause this?  I've installed quite a few systems over the years, and this amp was replacing an old one, so I don't think I did anything wrong...

grab a meter and actually meter the power and remote connections at the terminal connector......do you have power right at the input of the amp?

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979