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Assessing/Repairing Dead Speaker

Discussion in 'Electronic Repair Modifications DIY' started by kmetal, Jun 26, 2014.

  1. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Hey all, i finally got around to fixing my car stereo, which is a 'component' system, where the speakers have separated mid/tweeters and a sub box in the trunk, nothing fancy, stock (radio head unit) power for the mids tweeter, 250w amp for the bass box.

    turns out my front 2 mid drivers are having issues. 1 is unresponsive, the other, is cutting in and out. ive tested the car connections and they are fine and power other test speakers reliably. there is some rainwater rust buildup from me leaving my windows open. i sand the terminals lightly and that brought the semi working speaker to its current state.

    ive also tried to apply the connections directly to the 2 wires between the terminals and the speaker cone. and the broken speaker was still unresponsive.

    so my question is where is the next place to go in narrowing down whats wrong, andpossibly how to repair these. i spent $150 a pair, so id prefer to fix this anyway possible, even if itisn't pretty, as long as they work. i also would like to keep them going so i can continue w a fully matched set in my car, as i use it to reference mixes. heres a pic of the broken one. all the connections seem to be physically strong, so my best guess would be some buildup of some sort interfering.

    any help would be greatly appreciated. heres a pic, and i can take more if iit would be helpful.

    image.jpg
     
  2. Boswell

    Boswell Moderator Distinguished Member

    I would disconnect and unbolt the other loudspeaker from the vehicle, take both of them indoors. Test them using a multimeter on resistance range and, if they show steady readings of a few ohms, wire each of them up to a hi-fi amplifier in turn to test them out.

    It's quite possible that they may show continuity on the meter but give no sound when music is played through them at low to moderate levels. This would indicate that the voice coil is stuck, either through corrosion or suspension misalignment. You could see what happens if you disconnect them and gently push the cone in and out a little way - if it appears to move freely, do you hear grating sounds of the voice coil scraping against the magnet?
     
  3. DonnyThompson

    DonnyThompson Distinguished Member

    I used to test the phase of used speakers by placing a 9v battery to the speaker terminals... this may be a better way than to chance pushing on it too hard with your fingers, and, it might shake that voice coil loose if there's any moisture-related corrosion binding it.
    Your pic doesn't show the face of the speaker...How's the cone, appearance wise? Is there any obvious staining or rot?
     
  4. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Thanks fellas, I'm gonna try what you segues tend when I can borrow a meter, and I'll post the results and hopfully figure it out from there. Much appreciated! Btw the surround is a little ripped from my shoddy install, but the cone appears quite clean and tidy, w no obvious staining. The water damage seems to be on the back side of the speaker. Should have something to report in the next few days.
     
  5. Kurt Foster

    Kurt Foster Distinguished Member

    if the surround is toast it's likely the speaker ate itself by extended excursion. get new speakers Kyle.
     
  6. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    I might just have too... I just wanna make sure there is no way to bring these back from the dead. Gonna get my hands on a multi meter and pursue this for education and hopefully the benefit of my pockets.

    The thing about the surrounds, is there are little tears in them from the screws that hold the. To the door, they are rated for more power than my radio puts out, but I'd have get the ohm details to make sure. But I really don't listen that loud either, but maybe a combo of rust, and the excursion cooked it.

    The other one is still in my car and if I bang on it when it cuts out, it starts up again till the next bump lol. I'm gonna pull it when I get back from NY this week. Here's a pic of the surround. Kinda tough to see but there are a couple of slits, top left, bottom right.

    image.jpg
     
  7. audiokid

    audiokid Staff

    I have a really good sniffer. What do they smell like. I can usually tell if a cone is cooked. It has a distinct smell that doesn't go away for years.
     
  8. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Well it's been a while I borrowed a meter, I just dunno what to select on the rotory selector. And also I'm not sure what I'm looking for in the readout. I've never used one of these meters before. image.jpg
     
  9. MrEase

    MrEase Active Member

    Ok, select the range "200" by turning the knob 180 degrees. This will show a maximum of 200 Ohms and is the most sensitive range. When you put the probes on the speaker terminals you should read 7-8 Ohms for an 8 Ohm speaker or 3-4 Ohms for a 4 Ohm speaker. If you see OL then the speaker is open circuit and the voice coil has gone, If you see a short (0 Ohms) then usually the voicecoil has overheated and shorted the turns. If you gently push in the cone, do you get a grating sound? If so that normally indicates there are loose windings on the voicecoil.
     
    kmetal and bigtree like this.
  10. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    If you have to replace them, I bet if you put NS10 speaker in you car, your mixes will improve ! ;)
     
    kmetal likes this.
  11. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Well good news. there is no crunching sound when I push on the the cone, and after a couple seconds of erratic readings the speaker reads 3.9 steadily. There was a staic sound Shen I moved the probes around on the terminals and it gets louder and softer. I'm guess this is the small electrical signal going they the speaker? The meter seems to spikes as j probe different areas of the terminals, but settle around 4.
    image.jpg

    I had sanded corrosion off of them when I pulled them in the summer. Think it was 320 or 220 I used, whatever was laying around.
     
  12. DonnyThompson

    DonnyThompson Distinguished Member

    "220...221... whatever it takes."


    ;)


    View: http://www.youtube.com/watch?v=iX3kxAA2L4Q
     
    kmetal likes this.
  13. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Priceless man, priceless.
     
  14. MrEase

    MrEase Active Member

    That could indeeed be good news in that the problem could be as simple as corroded terminals. Try to rig the speaker to a hifi amp or similar (not too loud!) and see if you have brought it back. Fingers crossed for you....
     

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