Rockford Fosgate M400-4 help

[rhempz01]

I have a Rockford m400-4 it has audio on 1 of the channels and none of the rest. Ps fets are all good. No shorts in any outputs. Didn't remove them to test them yet. I could use some ideas on what to look for. It has 3205's in the ps. And irfb4227 in the output stage of the amp.

 

[rhempz01]

It doesn't draw excessive current but it does load down my supply when it is hooked up. From the normal 12.5v to 10.9v?

 

[rhempz01]

Drive signal for ps is perfect.

 

[josesony68]

I also have the same damaged amplifier ...

it is not normal for it to go down from 12.5 to 10.9v ..

Do you have a scope?
If you have it, can you check if it has a square waveform in the output gate pins of the fet in the audio channel that works?

check the same on the three remaining channels

 

[rhempz01]

Yes I have a scope and the left leg of the output transistor . I should get a sqaure wave there as well?

 

[rhempz01]

Now I have 1.3a at 12.4vdc. looks good about to test for audio. If you need any measurements, I got u.

 

[josesony68]

Yes, you should get a square waveform on the left pin of one of the two fets (I'm not sure which one it is, or if it's both) corresponding to the audio channel that works.

 

[josesony68]

Do the other channels have audio?

 

[josesony68]

Thank you for offering to help me, in my amplifier I am stuck at the point where I can not see square wave form outside the ps, and I do not know if it really is like this or not ..
Also, I think that pins 11 and 14 of IRS2092S should have a square shape, which I do not have, as in pin 4 I should have a triangular waveform, which I do not have either.

I do not know, I'm lost.

 

[rhempz01]

No channels have audio just static. Loud buzzz. And I'll check the irfb4227 for you. All of them tested good?

 

[rhempz01]

Ok tommorow morning I put that amp back on the bench anch scope all those pins and legs of the outputs. Is that what those I/c are for each channel? It has all that paint or whatever it is. It stinks to soder on it. We'll figure it out. Man I just sold a good one too!!

 

[josesony68]

oops !! I thought I understood that one of the channels worked ..
What voltage do you have at the speaker output terminals?
Have you checked if the voltage on the pre-amplifier card is + 5 / -5v?

 

[josesony68]

Ok, tomorrow we continue, it's also late here, greetings.

 

[rhempz01]

No I have not what pins should I test? And I haven't shipped out the working unit yet if you need something from it I can crack it.

 

[rhempz01]

Isn't the op amp board marked? Where it should have -5+5?

 

[rhempz01]

I'll open the new amp and get you some pictures of the waves on the outputs, as well as the I/c's.

 

[josesony68]

+ 5 / -5v should you have on the output pin of the IC703 and IC704 regulators (7805 and 7905)

Yes, it would be great, if you have an identical amplifier that works, we can take it as a base to find the problems in the damaged amplifiers.