Rockford Fosgate T400-4

[mike49504]

I replaced the outputs in 2 out of the 4 channels . I turned the bias pots fully counter clockwise.

The problem im having now is 3 out of the 4 channels work great
The Left rear channel has a problem as soon as i connect a test speaker to it it throws the amp into thermal protection. Any Ideas??

[Perry Babin]

Confirm that all of the non-bridging speaker terminals are still directly connected to the amp's ground.

What does the left rear look like on the scope with no load?

[mike49504]

The negative of all 4 channels is connected to amps ground.

The rear left channel looks like the other 3 on the scope nice sine wave

[Perry Babin]

There's a problem if all negatives are connected to the amp ground. Re-check this.

[mike49504]

Ok my mistake the following are connected to ground

front left - right front + rear left - right rear +

[Perry Babin]

Are there any traces on the board that appear to have overheated?

[mike49504]

I found the problem i guess i over looked it . Amp had a bad emitter resistor in the rear left channel it measured 6.44K ohms.


Im moving on to the next amp hope you can help im gonna post a new thread in 2 mins

[Perry Babin]

Was it the red LED or the yellow LED?