Question about Jensen A400HLX Car Audio Amplifier

2 Answers

Jensen 400W A400HLX Power Problem

I have a Jensen 400W amp that I have been running for a couple years with o probem. I disconnected it for a while and ran another amp for a while until that one quit. When I hooked the Jensen back up, it worked for a couple months and the did the same thing tha the pioneer i had before it.

What it does is when i turn the amp on it turns on and then shuts off with the power protect light on. If I leave it on for a little bit, it will pop back on and then off instantly again with the power protect light on. Both the Jensen and the Pioneer amp that I have are doing the same thing.

Originally I thought it was a problem with the amps, but now I am wondering if there is something wrong with the car tht is messing the amps up. Any suggestions or help would be great.

Thank you for your time,

Posted by on

  • Jim Olmstead
    Jim Olmstead Sep 25, 2008

    If it is the transisters, I should be able to test them to findout wich one(s) is/are causeing the problem right? Or not? If I can figure out the bad one(s), I could possable try to make a replacement and see if it will work again. What do you think?

    Thanks again for the time and help,


  • Jim Olmstead
    Jim Olmstead Sep 26, 2008

    Thank you again for all the help that you have given me so far. I found the information that you gave me very informative and I will be kiiping it on hand while i continue my journey towards making this amp work again someday. In the mean time, if you don't mind me asking a few more question, I would greatly apreciate it.

    I have attached this picture of the amp tore apart. I am not exactly sure what parts i should be specifically looking at, but this is what i can see so far. If these are what i am looking for, I will do what is needed to test them and then I will have to find out where I can order the replacement parts.

    Thank you again for your help and time,



2 Answers

Yes, you should be able to find the defective transistors. It may be as simple as replacing the defective output transistors but there could be additional damage.

Read through the following page if you want to try to find the defective components. Let me know if you have any other questions.

Amp repair primer

Posted on Sep 25, 2008

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  • Master
  • 631 Answers

If the amps are going into protect mode, it's likely that the output transistors have failed in both amps. This can be due to many things. Generally it's caused by running the amps at too low of an ohm load. If you drive the amps hard on a daily basis, that can also cause the amps to fail prematurely.

Let me know if you have any other questions.

Posted on Sep 24, 2008

  • Perry Babin Sep 26, 2008

    The 6488s and the 64981s are the output transistors. The Z46s are the power supply FETs. The 1620s are the rectifiers.


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