Rockford Fosgate T400-4 audio problems

[rhempz01]

Audio has a very bad ground like noise. The front left seems to be the worst channel. It actually clipped when I attempted to listen to that channel. Not in protection no shorts in any fets in curcuit. When I touch u3 it is noticable though the output.

 

[rhempz01]

R111 in pre amp section is open a 50k 1% 0805 resistor.

 

[seankane]

This fixed the amp?

 

[rhempz01]

No sean just what I found I don't have that resistor. Maybe something close but I don't have a 50k

 

[seankane]

Ah OK gotcha!!

 

[rhempz01]

I can't find a 50k in the dozen or so amps I can't fix either so I order some with the parts to some other amps.

 

[rhempz01]

It acts strange I have had these amps have bad output that we're not shorted but cause audio distortion. Strange.

 

[rhempz01]

I just got two more prime amps with no shorted mosfets, or outputs just no audio?

 

[seankane]

Have you checked supply voltage to your op-amps and such? All regulators are working?