amp not working

Hi,

I had sombody install a kenwood amp (KAC-7201 800 watts) in my car, and soon as the stereo was turned on, the ground wire on the amp started burning.  However, the two 30 amp fuses on the amp did not blow.  Can anybody give me a clue as to what may have caused this, and what internal component part of the amp may have been damaged?  the front speakers were playing even while the ground wire on the amp was burning.  Please help. 

Togcha

Hi again,

I do not know very much about the installation, but the individual who installed it said, he installed several other amps just like the one I have and never had any problems.  However, I noticed that there were no fuses at the power lead coming directly from the battery which is very thick, almost the thickness of a car jumper cable, and the ground wire is much thinner, perhaps a 12 guage.  But I can't understand why the two 30 amp fuses on the amp itself, didn't blow.  Could there be an internal component failure?

As Bart Simpson might say, "Aye Carumba!"  There are so many things wrong with what you described... Did you pay someone to do this to your car?

First thing to do is DISCONNECT the positive cable from your battery.  You must fuse that cable.  Plus the ground cable should be the same size and current capacity as the positive cable.  How is the ground connected?  The fuses in the amp did not blow probably because there is nothing wrong with the amp.

I suggest if you DID pay the person who did this, you demand your money back and tell him I said he needs to return his installer license to the Cracker Jack box he got it out of.  Then go to a real installer in your area and pay them to do it right.

Hey DYohn,

I'm laughing right now about your last response, but it truely isn't funny.  I'm quite upset at this guy and his cracker jack box license.  What guage wire should I use for power and ground, (by the way, the ground wire was connected to the chassis) and what size fuse will you recommend for the constant power?   Could this possibly solve this problem, or could this have damaged the amp?   Thanks a million, man!  I appreciate your giving me your time!   God bless!

The KAC-7201 is a decent stereo amp rated at 150 watts per channel.  It can be bridged into a minimum 4-ohm load and is then rated at 460 watts.  The "800 watts" number is a peak rating and means nothing in everyday use.  Yes it is possible it was damaged by a poor install, but upgrade your power and ground first then test it..  Or take it to a shop for a bench test.

I recommend using 4-gauge power and ground cable.  Not because this amp needs 4 gauge necessarily but because you might want to upgrade someday and it's not that much more than smaller cable.  Fuse the cable with between an 80 amp and a 150 amp fuse within 12" of the battery.   Make sure the ground connection from the amp is solid and to bare metal on the vehicle's chassis and is no longer than 18."  Make sure the amplifier itself is securely mounted and not bouncing around the car.

Hey DYohn,

Listen, man, thanks a bunch for all your professional adivice!  I will take it and run with it.  Hopefully, the amp isn't damaged, and hopefully I can get back to you with results.  By the way I copied your "Big 3 upgrade"  which I might as well do in the process.   Peace!

don't get it.

although the install was done dangerously incorrectly (not fusing the primary at the battery) that had nothing to do with the problem you experienced.... i am a Kenwood warranty centre and see this problem often (very often) with this series of amps.... they made the ground foils far too thin in the power supply of these units and they have a tendency to "fuse" open as the unit is being pushed hard and begins to really draw some current... i upgrade the ground foils in the power supply to allow for a greater current draw whenever i get these units in for "no output"......

you'd think some engineer at kenwood would realize that ground is just as important as power.......

not sure.  What do you recommend in the 800 - 1000 watt?

How much do want to pay?  What authorized dealers are in your area?

I do not really trust those fuses that amplifiers come with - two of my 5 channel amps blew and started to smell like my truck was on fire but they never blew any of the fuses although the power supply MOSFETS and some of the output ones where blown / shorting out - wierd - but I guess the current draw when the transistors shorted was not great enough to blow the amps fuses but great enough to fry the amp...