Rockford Fosgate Punch 500.2

[caraudioguy2100]

I get positive 45 volts on the source leg of the 9540’s

 

[Perry Babin]

Do you have positive regulated voltage on pin 8 of the op-amps?

 

[caraudioguy2100]

Yes

 

[Perry Babin]

Lift Q18. Do the outputs still get hot?

 

[caraudioguy2100]

Reinstalled the negative rectifier and lifted Q18

Amp powers up normally and idles around 1 amp

 

[Perry Babin]

That seems like a biasing issue.

Are both rectifiers and both regulators in the circuit?

 

[caraudioguy2100]

Yes

 

[Perry Babin]

Reinstall Q18.

Short the bias transistors collector to emitter.

Does it draw excessive current?

 

[caraudioguy2100]

Instead of shorting the bias transistors .

I reinstalled Q18 and set the bias pots fully clockwise and powered the amp up .

Amp idles perfectly fine and plays clean audio .

I re set the bias .


Wondering have you ever seen this before ?

The bias pots work backwards you have to set them fully clockwise instead of counter clockwise

 

[Perry Babin]

I've seen it in other amps but not in any Rockford amps, that I can remember. Maybe seankane has seen it.

 

[seankane]

I have never seen that in a Rockford amp.

 

[objext]

Seems strange since all these amps seem to be basically the same topology from some dsms, early "." gray/gold series, black & grind, and this style that you're working on.

 

[caraudioguy2100]

I’ve never seen it either .

That’s why I set them fully counter clockwise and was having issues with the amp

I set them fully clockwise and then adjusted the bias and amp works like it should .

 

[Perry Babin]

I looked at the various 500 diagrams I have an none show a reversed pot configuration.

 

[objext]

I did have one that wouldn't bias and ended up having a bad bias pot

 

[caraudioguy2100]

Would you leave it the way it is since the amp is working correctly ?

Or dig into it deeper and see why the bias pots are reversed ?

 

[Perry Babin]

Didn't you work on only one channel?

 

[caraudioguy2100]

Yes

 

[Perry Babin]

Do the solder connections on the pots look factory or hand soldered?

 

[caraudioguy2100]

They look factory