Question about Infinity Reference 7541a Car Audio Amplifier

1 Answer

Amp install disaster...?

I just installed my infinity reference 7541a amp with 4 sets of kappa perfect components. i was doing a road test for sound, though not excessively loud as to not DAMAGE THE @#(*[email protected]! EQUIPMENT, and suddenly everything went quiet. the i had the input levels at maybe 2/3, far from the whole load. didn't help apparently. now, the led's cycle between 'clip' and 'protect' whenever i attempt to turn on the car with the amplifier's turn on lead still connected. the amp felt pretty hot when i got it turned off, even though it had plenty of ventilation room. probably melted something, and if i did im going to be pretty steamed. the amp was running for all of 30-45 minutes, mostly at a really really low volume. when i read the manual, it said that the light sequence corresponds to DC voltage on the output, and that it probably needs to be servies already. i'd rather do it myself if it's an easy fix, after spending so much on my car i don't want to fork out more money for a repair guy. any possible solutions?

Posted by Grant Lack on

  • djm123 May 20, 2008

    Same problem and found two capacitors blown on the two input channel sections.One for the rear channel C301 and the front C101.I have in mind that my input voltage was too high.I have a kicker KQ9 preamp equalizer that has a max input voltage of 10 volts but does not show output ,but I assume it can go higher that 10 since it is a preamp.My JVC head unit puts out 5volts max which is what the max of the 7541a.OOPs well now I need a schematic to try to replace the caps and see if that'll fix it.I guess I need an amp that will handle a preamp as I really like being able to set my equalization on the fly without having to keep pressing buttons :P

  • Mark Skinner
    Mark Skinner Dec 24, 2008

    Hello all, I have the same problem. I'm just getting into car amp repair as i'm an electronics repair tech that i went to a tech college for. Anyway I bought an Infinity 7541a for $10 off of e-bay. The page described it exactly. The protect and clipping LED's cycle back and forth. Like you said the manual just says DC voltage proble and needs to be serviced. I did a few tests and don't think the power transistors/mosfets are blown i believe the output transistors are blown. I took my DVM and took the positive probe to the Positive B+ voltatage where you hook up power to the amp then took the negative probe and touched it to the back side of the power transistors/mosfets and got a reading of zero. Mind you the meter is set to the diode test setting and board out of enclosure. Now i have a brand new amp that is out of the enclosure that works fine and got the same reading. Then touched the negative probe to the back of the output transistors/mosfets and got no reading at all on the infinity amp. So I did the same to the working amp and the reading climbed until the meter reached its limit. Went back to the bad amp one more time and did the same test and still no reading. I'm thinking the output transistors are no good. Any help is greatly appriciated if anyone else has fixed thier Infinity 7541a amp. Please anyone let me know. Thanks



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Try first to disconnect all of the speakers on the amp. See if the amp will turn on now. If not , the amp has bad output devices, or drivers, and or the switch mode power supply is fried. There is no easy fix with solid state elctronics as there are no user serviceable parts inside. The units going to need to be repaired by a service tech unless you know how to solder, unsolder, test mosfets, transistors, and diodes as well as resistor.

Posted on Sep 22, 2006


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