Help with Bias current Rockford Fosgate Punch 400.4

[Juliano z]

Hello

I live in Brazil, and I love the Rockford fosgate amplifiers.
I always do a lot of research here in this forum, but I registered here in your forum recently.

I am restoring two old Punch 400.4 (1997), and I do not find much technical information about them. I need to adjust the BIAS current, but I can not get correct information about it. I just need to know which adjustment procedure, or some technical manual that contains the voltage and current values, necessary for me to adjust the Bias.

I found a topic here, which says to set from 4 to 5mv on top of one of the 0.1R resistors. I adjusted this way, but the amplifier generates a lot of heat, and a 2A consumption at rest, which I found quite high.

I could not find the amplifier service manual.

Sorry for the writing! haha

 

[Perry Babin]

5mv is commonly suggested but as you found, it's too high. This is how I set the bias:
http://www.bcae1.com/temp/ausettingbias.swf

 

[Juliano z]

5mv is commonly suggested but as you found, it's too high. This is how I set the bias:
http://www.bcae1.com/temp/ausettingbias.swf

Thanks for the quick response!
In this case of the link, do I need an analog ammeter?
I have digital ammeter on my test power supply.
With the 4 channels set at 5mv, the amplifier consumes 2A idle.
In the 400.4 user's manual it does not say idle consumption. Would you have this information?

Thank you!

 

[Perry Babin]

What's important is that the idle current just start to increase. You can use any amp meter.

 

[Juliano z]

Thank you, I'll follow your procedure.

Here in Brazil, we do not have much information about these amplifiers.

 

[Perry Babin]

Download this:
http://www.bcae1.com/temp/RFG-1400A.zip

 

[Juliano z]

Download this:
http://www.bcae1.com/temp/RFG-1400A.zip

Thanks a lot for the help!

Exactly this I needed, now I have manual, schematic and test procedures.

And really, in the procedures is recommended 50mA (5mv) per channel, but I'll leave a little less. I tested with 4mv, and the exact consumption is 1.8A.

Thank you.

 

[Perry Babin]

1mv is plenty.

 

[nigelwright7557]

I design quite a few of my own amps so there is no bias setup routine.

So I apply a sine wave to input and monitor output on a scope.
I turn up bias slowly until crossover distortion goes.
Quite often the bias current is as little as 10mA.

On quasi amps I often find zero bias current gives no crossover distortion.

 

[Juliano z]

1mv is plenty.

Yes it's true

I design quite a few of my own amps so there is no bias setup routine.

So I apply a sine wave to input and monitor output on a scope.
I turn up bias slowly until crossover distortion goes.
Quite often the bias current is as little as 10mA.

On quasi amps I often find zero bias current gives no crossover distortion.

I think it depends a lot on the design of the amplifier.
I do not have scope, but I would like to take this test on fosgate punch.