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amp has power but subwoofers have no sound

Car Audio, Video, & GPS

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amp has power but subwoofers have no sound

  • yesterday i went out to my car to discover that my tire was flat so i had to get out my spare from under my sub box. thats not hard just push them towards the back and grab the tire from the passenger compartment. however in the process of moving my box the ground wire came loose from the amp and in the process came in contact with the hot power supply which caused a pretty impressive spark. well. i didnt deal with it yesterday fearing the worst the whole time while dealing with my tire got my tire fixed today and went to check the status of my audio equipment so i reconnected the ground wire and turned on my car's head unit. the amp's power light did come on but it didnt seem that my subwoofers were working so i popped the trunk and went to look and sure enough they didnt seem to be on so i tried a few songs that should get some response and nothing what happening. i made sure that all of the appropriate cables were plugged in and all the wiring seems fine but still no sound. i figure i fried something but i dont know how to tell.. does anyone know what i should do to try and fix it? -thanks



    [edited by: Ryan at 4:06 PM (GMT -5) on Wed, Mar 16 2011]
  • IF you have a DMM i would make sure your RCAs are getting a signal to the amp.. also check your sub wiring.. at the amp.. at the box terminals and inside the box at the subs :) start there.. and see what happend

    JVC KD-AVX44, 2 Massive Audio Hippo 8's , Hifonics Colossus going back in soon, MB Quart ONX216, Fli audio FL450S-F2, Energy ENC693x2 in rear deck, 6 gauge kit plus a huge 3 gauge kit. Custom built box for my 8's :)

  • at risk of sound like a complete eletronics noob how would i do that? what would i be looking for?
  • naa u dont sound like a noob.. alot of people dont know howto.... you get your DMM and put it on AC ... now pull out the RCAs from the amp.. and check the RCA's while playing a song. Do you see a voltage there? It should bounce around but you will get voltage on both the RCA's. Simple touch the red lead to the inside plug of the RCA.... and the black lead to the outside. See what you get. If nothing.. your problem lies in those RCA's or the headunit. if you have voltage there.. plug them back in.. now change to DC volts.. touch the black on the ground of the amp.. and the red to the Positive. you should see 12-15 volts there.. If not.. your amp is not getting enough power.. now change back to AC volts... disconnect your subs or speakers.. play a song without any subs or speakers connnected and touch the amps speaker outputs.. Red lead on + and black lead on - again.. make sure your on AC volts and this reading will also jump around just like the RCA's. If everything but this step went fine.. the amp has a problem.. if all these tests work out great.. then the problem lies within the subs wiring or the subs themselves. Let us know what tests work and what ones fail and i could tell you exactly where the issue is and we can go from there :)

    JVC KD-AVX44, 2 Massive Audio Hippo 8's , Hifonics Colossus going back in soon, MB Quart ONX216, Fli audio FL450S-F2, Energy ENC693x2 in rear deck, 6 gauge kit plus a huge 3 gauge kit. Custom built box for my 8's :)

  • One semi-obvious thing is be careful for example that you ONLY touch the ground with one test lead and the POS with the other test lead.  If you accidentally touch both points with the SAME test lead, you can short out the amp.  (Applies to all the tests).  It's not something that would be easy to do, but it's something you should be aware of.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • BloodyZero
    ...the ground wire came loose from the amp and in the process came in contact with the hot power supply which caused a pretty impressive spark. well. i didnt deal with it yesterday fearing the worst the whole time...

    I don't think it's all that complex of a problem.  Even if you're not familiar with systems at all, this should still be a pretty easy fix.  You blew a fuse.  The amp's light that comes on may not tell you much, as it is often given power from the remote turn-on lead.

     

    If it had not been fused you could have quickly had a fire.  Look next to the battery and (i'm praying) there will be a fuse holder within 18" of your battery with a blown fuse in it (not optional, required!).  Make SURE the wires are properly secured so as not to be pulled loose by cargo.  If the box isn't bolted down (preferred method) than at least use brackets and screws.  It will make it sound better and just maybe save a life!

     

     

  • Good point J Ro - also, it might not be the main fuse - check the internal fuses in the amp and if there is a distribution block, the fuses internal to or after it also.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • i didnt even think of checking the main fuse on the power line (because the light was coming on) the one on the amp looked alright but i didnt actually pull it out because it was being stubborn and i didnt have time when i go back down to go to work ill check those hopefully one blew and not any hardware.
  • i checked the fuse leading from the battery and the fuse sticking out the side of the amp and they are both intact.
  • BloodyZero
    i checked the fuse leading from the battery and the fuse sticking out the side of the amp and they are both intact.

    I hate when it's not easy.  A number of things could be causing your issue.  The RCA's may be bad, the amp may be bad, the speakers may be bad, and any single wire may be bad or pulled loose.  A digital multi-meter (DMM) will help.  shak made good suggestions.  Here's the most likely places to find the problem:

    Confirm that you have 12+ volts by measuring the DC voltage at the amplifier inputs by probing the power and ground inputs with a DMM set to DC volts.  If there's no reading, the ground may have pulled itself loose or there could be another fuse holder elsewhere. 

    Measure the speaker impedance from the amplifier's output by disconnecting the speaker leads and probing them with your DMM set to ohms.  A reading of zero suggests a wire got disconnected. 

     

     

     

  • J Ro
    A reading of zero suggests a wire got disconnected

    Or more likely infinite - usually shown by a "1" at the left of the display.

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • im still working on getting a dmm im in the army and the one i had of course got left back home so ill be headed to the store sometime soon in search of one. as soon as i acquire one ill post what i have found.
  • i figured it out.

     

    its funny i went and bought a dmm and didnt get a chance to check out the problem until today because i have a 4 day weekend this weekend and i came home. when searching for a screw driver and found one right next to the dmm that i have here.

     

    i started out with removing the inline fuse on the power line then turning on my head unit to check to see if the light on the amp is powered by the remote wire. which did not come on. so i put the fuse back in.

     

    then i pulled the RCA cables from the amp and attempted to check them with my dmm. i prodded around for a while reading instructions and switching settings and i could not get a reading from my RCAs so i figured 1 ithey didnt have power 2 i was doing it wrong. so i moved on

     

    i switched my dmm over to dc 20 and tested the (+) and the (g) cables and recieved a 12.31 so the circuit to the amp is good.

     

    i pulled out the speaker wire to the amp and prodded the (+) and (-) speaker outputs with no results once again checking all my settings to no response. which i was expecting as i had decided that the amp wasnt even getting anything to put through to the speaker outputs.

     

    next step i decided to check the RCAs at the source so i began removing my console as i have become so familiar with due to the crazy wiring and cable management i have done in the past (extra 12vdc outlets for old needs from when i was a volunteer firefighter with emergency lights that i didnt want to occupy the outlets i needed to use for other things and routing wires so that they were not visible from the outside) so anyway i pulled out the screws and slid out my head unit and noticed that my RCAs were not even attached -.- so i plugged them in and bam instant working subs...

     

    i am not entirely sure how that happened i can only assume when my tire was flat and i had to move my box that i pulled tension on them and popped them loose it was only a coincidence that i had also pulled loose the ground cable and managed to cause a pretty impressive spark that really didnt do a thing to my system. 

     

    anyway thank you all for the assistance even if nothing major was wrong i learned alot about wiring and electronics.



    [edited by: BloodyZero at 2:29 PM (GMT -5) on Thu, Mar 17 2011]
  • Glad the mystery is finally solved!

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs