punch 500x bias voltage

[Hexhclass]

I do not have one but i will find it.Is it to limit the current?

I am using a 50w light bult as a limiter.

 

[Perry Babin]

I wouldn't use the lamp. A 12v lamp will blow relatively quickly at anything above about 15v and the amp could easily drive 20+v into the lamp/resistor.

Connect the resistor across the output and do whatever you were doing to make the amp draw current with the bias pot fully counter-clockwise. Does the resistor heat up?

Is there any DC voltage across the resistor when the amp is drawing excessive current?

 

[Hexhclass]

I used a 3.4 ohm 30w resistor
I connect it on the bad channel and it is not heating up.
Voltage across the resistor is .8mv
voltage across emitter resistor .3mv

 

[Perry Babin]

Did you do the same thing that you did when you had 4.3mv with the bias set fully counter-clockwise?

 

[Hexhclass]

yes,

 

[Perry Babin]

I don't have any more suggestions without a scope. It appeared to be oscillating but if the resistor didn't heat up, it probably wasn't oscillating.

 

[Hexhclass]

I will just remove the outputs in the bad ch.The owener only need on ch for a sub.
If the resistor was heating up where whould i have to check for the fault?

Thanks for the help