Bias adjustment for Punch150 transistor outputs

brandes.cm · 7th July 2010, 08:58 PM

Is the adjustment the same as the fet based outputs? Normally I monitor the voltage across my current sense resistor in series with incoming power and watch for it to take off. I then back it off a touch. I don't notice the "take off" point on this amp.

Cory

Perry Babin · 7th July 2010, 10:20 PM

I think all Rockford amps tend to increase significantly at some point. Which components did you replace in the audio section of the amp?

brandes.cm · 7th July 2010, 11:39 PM

I didn't adjust far enough, about 3/4 turn of the pot it finally increased like I expect. Most of the newer amps don't get much past half turn before they increase. That is why I ask the question.

This amp had blown Buz11's in the power supply and one channel had a shorted 2n6487 and 2N6490. This amp was untouched when I got it, all components were originals, no signs of rework. The bias pots seem to be in the same position as when I recieved it.

7th July 2010, 08:58 PM	#1
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Bias adjustment for Punch150 transistor outputs Is the adjustment the same as the fet based outputs? Normally I monitor the voltage across my current sense resistor in series with incoming power and watch for it to take off. I then back it off a touch. I don't notice the "take off" point on this amp. Cory

7th July 2010, 10:20 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I think all Rockford amps tend to increase significantly at some point. Which components did you replace in the audio section of the amp? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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7th July 2010, 11:39 PM	#3
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	I didn't adjust far enough, about 3/4 turn of the pot it finally increased like I expect. Most of the newer amps don't get much past half turn before they increase. That is why I ask the question. This amp had blown Buz11's in the power supply and one channel had a shorted 2n6487 and 2N6490. This amp was untouched when I got it, all components were originals, no signs of rework. The bias pots seem to be in the same position as when I recieved it.

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