MTX mxa8001 - Broken & fedup

[vr4]

Damn.

I hooked everyhitng up. Again using my 1/2 size 15 & 20 amp fuses. (as opposed to factory 30 amp fuses)

then i turned everything on. I blew all 3 fuses.

I believe the fuses blew before i put my key into my ignition. - meaning that all 3 fuses blew prior the amp recieving the power on signal.

Were the fuses i used too small? - does anyone have any suggestions on what do to now?

[Perry Babin]

The fuses should not have blown.

Disconnect the speaker wires and signal cables from the amp and replace the fuses. Do the fuses blow before or after remote voltage is applied?

If the fuses don't blow, check the wiring. If the fuses blow, you need to open the amp to see if you can find the problem.

You may also want the see if you have 12v on the case of the amp. If you have it mounted to the vehicle and there is a short from the B+ supply to the case of the amp, that could cause it to blow the fuse.

[vr4]

------SUMMARY ----------

--------------- History of amp ------------

Ok here is the story;
http://s234.photobucket.com/albums/e...t=IMG_3721.jpg

I purchased a brand new MTX mxa8001 a class d mono-block amplifier from circuit city about 2 years ago on sale. At that time i was driving an old civic hatchback and just didnt have the room for it, so it sat waiting for me to get a new car. I finally got a newer car a year & 1/2 ago, and set the audio up in it. I wired in this amp and attached to a smaller 10 inch sub- just to test to make sure all is well. I tested the system, and sounded great, for the first 5 min, then the 30 amp inline fuse for the power line blew, and i figured, man these monoblock amps draw alot of current.

It was 6 months before i hooked the amp up again and my prized mxa8001 amp is dead.

- The amp -
When just connected to power and ground it gets hot. at no point does it output any signal, nor does it turn on. It just gets hot.

----------------------- The fix ----------

When i took the amp apart i found a chared negative rectifier.
http://s234.photobucket.com/albums/e...t=IMG_3744.jpg

I pulled the negative rectiier - and determined it was bad. -It appeared to have shorted to the alumnium heatsink beneath it and burned a little hole in the metal. I replaced this rectifier.

I also pulled the positive rectifier next to it. It tested OK.

I also tested all FETs by checking for shorts between the 3 legs. All fets tested OK.

------------------ Testing the fix -------------

I plugged it in with small fuses and blew all 3 of them. I believe the fuses blew as soon as power was connected*. The speaker never made any noise. (I only checked the fuses after turning on my ignition. But i believe the fuses blew as soon as power was connected. )

--

[vr4]

Perry - great advice.

I just did a process of elemination on the amp.

first i hooked up just....battery & ground
then i hooked up just....battery ground and remote
then i hooked up...........battery ground remote and a new audio signal
then i hooked up...........battery, ground, remote & old audio source (head unit)

this is pointing towards a speaker problem /speaker wiring problem. Im gonna pull the speaker out right now. will update in a few min.

[vr4]

Found a cut in the speaker wire!

im gonna go hook it all up now - will post what happens!

[vr4]

Fixed!

Put everything back in. Fresh wire- and sheilding where it rubbed through. Fixed and sounds great!

Perry - I need to personally thank you. You walked me through the diagnosis and repair of this amplifier from start to finish. You even caught and corrected my mistakes.

Thank you for all your help. Also thank you to the diyaudio community.

Hopefully i will be able to give back in some way.

For anyone who might need it - I have an extra FEP16DTA

as well as 2 FQA19N20C and 2 HUF75339P3.

hope this can help some one else out!

thanks again to everyone!