Soundstream Ref 404s Blows fuses

[MagicMike75]

Hi there

Reference thread: http://www.diyaudio.com/forums/car-audio/190849-soundstream-reference-404-a.html

I have a similar issue. My 404s worked perfectly since new and just recently blew fuses at start up. It blows fuses just as soon as the remote is turned on without any outputs connected.

Based on what I read here I found one of the FET's bad and replaced all 4 with 2 FEP16DT & 2 FEP16DTA

I re-assembled plugged back in and blown fuses again.

I removed all power supply FET's from section 1 in the photos here and all test ok.

I did notice that the PCB trace going to the middle leg of the top regulator in section 3 was burned up so I made a bridge to replace it. Its unclear if the trace also went to the top leg as well.

Any thoughts or suggestions?

Thank you in advance.

Mike

 

[Perry Babin]

The two part numbers that you posted are rectifiers, not FETs.

Desolder 1 wire of each color from the inductor (circuit board designation L2). Does it still blow the fuse?

You should be using nothing larger than a 15 amp fuse while testing.

IF you haven't done so already, read the basic amp repair page (link in sig line below).

 

[MagicMike75]

Hello,

Thank you for the response. I appreciate your time. Yes I read the other post about 10 times so I was a little confused with the nomenclature as I was writing my post. I replaced the rectifiers. I have desoldered 1 wire of each color from the inductor as instructed and it does not blow fuses. Also, I only had 7.5A and 20A remaining tonight so I opted for the 7.5A (x2) for the test. Although I got a spark when connecting the power the fuses did not blow. The amp did not show any signs of life at all (i.e no indicator lights).

Also, I did read the your links, if I'm not mistaken I think I found your link on google and it brought me here Thanks for the help.

What do you think?

Thanks,

Mike

 

[MagicMike75]

Thank you for posting and thank you for the clarification. I read the other post so many times I got the terminology mixed up when I posted.

I did as you instructed and desoldered the two leads closest to the (2) caps. I installed (2) 7.5A fuses and they did not blow when applying power. I did get a small spark when connecting to the battery though. The amp shows no signs of life.

What do you think I should check next?

Thank you,

Regards,

Mike

 

[Perry Babin]

It no longer blows the fuse. That seems to indicate that there is a shorted output transistor. Have you checked all of them carefully?

 

[MagicMike75]

I did manage to check the all of the output transistors this morning prior to heading off to work and they seem ok. I dont get a dead short in any combination between the legs. I did double check the 2 regulators (where I stated before the trace had melted on the board) and the other one does not show a short but it does read .001 with the meter set to mega ohms. I did notice as well that it appears the regulator with the burned trace looks like it burned a hole through the isolation material and grounded out on the case. I have since cut a new piece of material to cover the hole.

I'll be removing the questionable regulator to see what they read off the board.