Amp turn-on failed??

Discussion in 'OT Technology' started by MovieMan84, Dec 10, 2006.

  1. MovieMan84

    MovieMan84 Here we go

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    So I noticed this problem when I turned my car on this morning. I have sound coming out of the rear speakers (driven from the head unit), but not the fronts or the subwoofer (each on seperate amplifiers).

    The system is as follows:
    Car: 1996 Subaru Legacy
    Head Unit: Pioneer DEH-7500MP
    Amplifier (front speakers): older Pioneer Premier 2x100 @ 4ohm amp
    Subwoofer: Infinity Basslink 1
    Wiring: 4ga wire through a fuse from the battery to a fused junction box. 8ga wire from the junction box to the front amp, 8ga wire from the junction box to the basslink. Front amplifier is under the driver's seat, subwoofer is bolted to the back seat, each is grounded seperately to a metal bolt.

    So I figured I bumped something on the basslink and blew a fuse. The first thing I checked was the fuse at the battery, then the fuses in the junction box. All of those are ok. I used a multimeter to check voltage at the amplifier and subwoofer terminals - both of which come up to about 12.7 V with the car off. Then I pulled the head-unit out to make sure everything is connected. I checked the turn-on wire, which gives resistance between the pioneer harness and the connection on the amplifier of 0.5 ohms. Neither the amplifier or the sub is turning on.:greddy:

    Am I missing something, or did the turn-on circuit in my head-unit fail like I'm guessing it did? Any suggestions on other things to test before I buy a new head unit?

    Cliffs: amp won't turn on. Amp turn-on wire connection is good. Amps are getting power. No fuses are blown. Any suggestions?
     
  2. MovieMan84

    MovieMan84 Here we go

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    Also, as a followup question - does anyone know how the turn-on lead works? Is it just a low-current 12 V signal, or is it more complicated than that? If it's just 12 V active-high, can I just connect the + terminal of my cigarette lighter to the turn-on lead and see if the amps come on?
     
  3. rebs

    rebs shares AIDS OT Supporter

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    its a simple 12v source, you can connect it to accy in the ign harness if you must.
     
  4. intgrakid88

    intgrakid88 New Member

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    def try jumping power to the amp from you accessory like you said and see if that lead is your problem...the best thing to do is get one of you friends to swap amps with you pulg his into your car and yours into his see what works and take it from there obv if his works in your car and your dosent work in his then its the amp or if they work in his and not yours its something with the wiring
     
  5. MovieMan84

    MovieMan84 Here we go

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    Yeah, I thought about that, but I know the amps are getting enough power (and I don't know of anyone right off who has an amp and would let me swap it out).

    I'll test out the turn-on wire with the ignition/accessory this weekend when I have some time and see if that fixed things.
     
  6. CrazyInteg

    CrazyInteg Honda-Acura.net OG

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    So what did you find? My dad has the exact same issue.
     
  7. MovieMan84

    MovieMan84 Here we go

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    Actually, funny thing happened. My girlfriend and I were going on a trip this weekend, so I had opened the trunk of my wagon and was sitting in the back waiting for her to come out of her house. I had a power adapter for some random piece of electronics just laying back there, so I decided to try direct-connecting the subwoofer amp turn-on to the power in. Sure enough, the whole circuit came on and stayed on. I took the subwoofer apart on Sunday night and found 6-8 dead bug carcasses jumpering the turn-on terminal to ground...so I think I quite literally had a bug in my amp system :eek3:

    Problem solved for me though - I cleaned up the subwoofer amp terminals, put the wiring back in, and the problems are all gone. I'd recommend making sure that no part of the turn-on circuit is grounded, because if it's wired like mine, it's all one circuit, so grounding any part grounds all of the amps.
     

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