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car audio question regarding stiffening cap

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  • car audio question regarding stiffening cap

    I purchased a car from a friend that already had a nice audio system installed. It has worked fine for over a year and suddenly quit. It works first thing in the morning for about 20-30 minutes before it cuts out, then it's dead for the rest of the day, even after sitting unused during "working hours."

    There are two amplifiers, one for the sub-woofer, and one for the rest of the speakers. My problem appears to be with either the stiffening capacitor or the main amplifier. The cap - a Scosche .5f cap - has some circuitry and a digital voltage display on top. I've noticed that when I get no sound, the main amp power light is out and the cap voltage display reads flashing zeros. Weird thing is that the sub amp, which is powered from the same cap, has its power light on. It's signal is fed through the main amp.

    I figure the problem has to be either the cap or the main amp because it DOES work at least for a while each day. Before I start pulling stuff apart and trying to isolate the problem, I wanted to post it online to see if anyone had any experience with this sort of thing.

  • #2
    Other than its display, the cap probably useless... (They are usually NOT worth buying, but since it's already bought...)

    However the problem probably isn't the cap since it is in parallel with the supply and amps (ie, across the supply) and if it were bringing down the supply, it would bring down the other loads (and blow a fuse).

    It is probably a connection fault - probably a poor connection (or broken wire) that heats up until it cuts out.

    A voltmeter would be handy for testing. If the voltmeter in the cap can be isolated (leaving the cap there but disconnecting & extending the voltmeter's (thin) +12V red wire), you could use that.


    • #3
      Careful around the cap! They can put out a lethal amount of power!
      Originally posted by ghettocruzer
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      • #4
        Batteries put out more...

        But yes - assume it is a battery.
        (Caps & batteries are analogous - a battery being "a fracken big capacitor".)

        (To clarify, batteries & caps may be (charged) at 12V, but caps will often have lower internal resistance, hence deliver higher initial current. But that is short (love the pun!) lived - the battery will keep supplying current....)


        • #5
          problem resolved

          Thanks for the suggestions. Turned out to be a dirty connector. After thinking about it, I realized the problem began when my battery was replaced. Then I remembered that my positive battery terminal was ALSO replaced. I took the cables for the stereo off that and, sure enough, they were somewhat corroded. A little dremel work and they were shiny copper again. Problem solved.


          • #6
            Originally posted by OldSpark View Post
            It is probably a connection fault - probably a poor connection (or broken wire) that heats up until it cuts out.
            Hate a smart R's.


            • #7
              kinda why I said "Thanks for the suggestions" right there at the beginning. (nudge nudge, wink wink)


              • #8
                Alas I'm just figjam'ing & big-noting myself...
                I've recently gone thru a phase of the "how would you know" or "that's crap" crap.
                But this and a few others have been easy problems with easy likely solutions that I have scored.

                I'm thinking maybe people will be keener to test the correlation between these easy solutions and the others I propose....
                I know I'm probably right, but I couldn't be bothered shoving it down peoples eyeballs....