Question about Car Amplifiers

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Car amp my protect light stays on even though everything is hooked up right.

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Re: car amp

The most common reason for this is shorted output transistors. To confirm that the problem is in the amplifier, disconnect all speaker wires and the RCA cables. If the amp still goes into protection, check the DC voltage across the B+ and ground terminals. It should not drop below 11 volts. Also check the remote voltage.

If the amp continues to go into protect with no external connections (other than B+, remote and ground) and the voltage remaiins above 11v, the amp is defective.

Posted on Nov 06, 2007

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Re: car amp

Pbabin's solution is correct for most amplifiers, but isn't exactly the case for this particular amplifier. Infinity has been a good name brand, making quality stuff, and was the 'upper line' of JBL made by parent company harman. This series of amps, however is junk compared to previous series, and does not even come close to the quality of even a JBL amp. I think the company might have been sold, and the buyer used the nice marque to sell cheaply built amps. I have been repairing amps for years, and I have 2 of these sitting here that check out fine across the board, but for some reason the protection circuit is still shutting down the amp. The protection circuit is supposed to protect the circuitry when a fault occurs, such as touching the speaker wires, or grounding out. This series of amps seems to have a fatal flaw, in that once the protection is triggered, it never releases, even though the circuitry of the amp is perfectly fine and would operate as it should. So with that problem, on top of the fact that the protection trips much easier than it should, means there are a whole lot of these amps out there that are unusable. I was able to bypass this protection circuit on one amp, but the time and effort involved in doing that are not worth it to save an amp of this quality. I was always a fan of infinity stuff, but it appears they have either gone down hill, or this series of amps in particular suffers from major design flaws. I cannot speak of the company as a whole, as I have not messed with any of their higher series amps that are this new. This model in particular seems to be the worst of this troubled series. If there are any other techs out there that can devise a way to reset this protection circuit, I'm all ears, but it's a custom IC that controls this function, and I can't find data on this chip to know what pins do what. If you can find info on this chip, you could put a momentary switch on the side of the amp to reset the circuit, and this would allow continued use of these amps.

Posted on Aug 12, 2008

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1 Answer

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Ok check the remote wire running from the headunit to the amp should be giving v12 feed whiles headunit is on.

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take cover off the amp as the circuit may be over heating.

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take the amp out and hookit up to the car battery and let it charge then unplug it do this a couple of times then rehook it to the cars audio system it sounds like your amp may be locked..

also check your speaker wires from amp to speaker box then from the back of the box to the speaker inside the box you may have a short..

thats where i would start.. hope this helps

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Hello. First, disconnect all of the speakers the amp is driving and the rca inputs while the amp is off. Now power on the remote. If the prot. light still stays on you will need to varify that the voltage across the ground and b+ terminals is a minimum of 12 volts. If this is true than your amp may be damaged due to shorted parts. Otherwise, try to repower the amp while a speaker is connected and if it is O.K. than there may be a problem with the RCA ground in the head unit or the amplifier. We service these amps at Sound Repair 321-690-0808.

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Hope this helps, and please rate my advice.
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Larry T
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