punch 500x bias voltage

[ian33]

what voltage should the bias be in this amp?

i also have a small punch with no info on it.It is a two channel using 1 irf540 and 1 irf9540 per ch.Two PS FETs.I set this one at 0.1mv and it seems to be playing good.Any idea where it should be?

[Perry Babin]

This is how I generally set them for Rockford amps.
http://www.bcae1.com/temp/ausettingbias.swf

[ian33]

The amp has 4 ports .If i set one at the right gage how would i no when the oder 3 is at the right gage?

[Perry Babin]

Each channel would show the same tiny increase in current draw.

[ian33]

One of the channels is giving me a hard time to set.I set the other 3 ch @0.2mv but the next ch bias starts at 4.3mv and up.I change the port but no change.

Also the 2/4 ch input switch in making the amp draw more current when it is in the 2 ch position.where does this switch have to be when setting the bias?

I have a 50w light bulb for limmiter

[Perry Babin]

The switch shouldn't make a difference in the idle current. Don't have speakers or RCAS connected when setting the bias.

Did you replace the outputs in the channel with higher bias?

[ian33]

I only replace 4 PS FETs
I think the owener of the amp turn up the bias trying to get more power from it.

The input switch is making the amp draw a little more amps when it is set to 2ch

[ian33]

I found a leak on one of the FET in the same ch.I will change it and see what happen

[ian33]

I used a next meter and FET is good

[Perry Babin]

Short the collector and emitter of the bias channel for the defective channel. Does that cause the bias voltage across the source resistors to go to 0.000v DC?