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Reload Thread: Amp not working, cant figure out the weak link.

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    BobTheSlob's Avatar
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    Amp not working, cant figure out the weak link.

    I have a Kenwood KDC-MPV619 HU. My amp is a Cadence Q3000; it's 100x2 @ 4 Ohms. One day, while I was driving home from school, my sub just quit working. When I opened my trunk, the "Diagnostic" light was turned on. I went on Cadence's website, and it said the Diagnostic light turns on when there is a short in the speaker cables, or the RCA cable/HU giving off DC voltage.

    So, I first checked if it was the speaker. I turned off my car, took the speaker cable OUT of the amp, and turned my car back on. Diagnostic light was still on, so it isnt the speakers.

    So next, I pull out the RCA cables. The diagnostic light goes off, but the power light isnt on either.

    So I replace the RCA cable. Diagnostic light is still on.

    What else could be stopping my amp from working?







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    Randy Savage's Avatar
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    Check the current that the amp is receiving. Most amps will go into protection when the amp is seeing too little current (somewhere around 9v on most amps I believe)...

    Might be your alternator going out, or your battery dying...





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    Re: Amp not working, cant figure out the weak link.

    Originally posted by BobTheSlob
    So next, I pull out the RCA cables. The diagnostic light goes off, but the power light isnt on either.
    That means the RCA cables are supplying the ground connection to your amp. DC current through the RCA grounds is what the diagnostics light is telling you.

    Rewire the ground connection on the amp.



    dave
    ----------
    1999 Buick Park Ave Ultra
    Head Unit: JVC KWHDR720
    EQ: Audiocontrol EQL
    Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
    Sub Stage: Boston G3 10", 0.5 cu ft sealed
    Amp: PPI Phantom 900.4
    Rear Fill: Boston SE953 6X9's

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    ****. YOu sound confident. I'll go try that now




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    ****it! Why won't anything work! I reconnected the ground connection, and still nothing. It's just "Diagnostic"




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    maylar's Avatar
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    Something's fishy. You need a voltmeter or 12 volt test light to proceed...

    Disconnect the RCA cables and turn on your system. From what you said before, the amp should power off. There's no reason for that unless you're not getting ground to the amp.

    Now check voltage between the amp's ground terminal and a clean ground point on the car's body. If you get voltage there, then the ground wire you're using is hosed.

    If there's no voltage there, then check voltage between the amp's metal chassis (or one of the RCA input sleeves) and the car ground. If you get voltage there, then there's something wrong with the amp's ground terminal.



    dave
    ----------
    1999 Buick Park Ave Ultra
    Head Unit: JVC KWHDR720
    EQ: Audiocontrol EQL
    Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
    Sub Stage: Boston G3 10", 0.5 cu ft sealed
    Amp: PPI Phantom 900.4
    Rear Fill: Boston SE953 6X9's

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