Rockford low power

[imraneesa]

So, is the maximum output from both channels 3v AC?

yes both channels have only maximum 2.8v~3v ac on outputs.

 

[Perry Babin]

That's very strange that it's clean but low.

What is the DC voltage measured directly across R206 and R306?

Do you see essentially no signal on either side of C301 and C204?

 

[imraneesa]

That's very strange that it's clean but low.

What is the DC voltage measured directly across R206 and R306?

Do you see essentially no signal on either side of C301 and C204?

There is no voltage across R206 and R306.

C301 and C204 has slight signal on negative side.

 

[Perry Babin]

I've never seen clean audio pass with no bias for the differential amp. Do the bias pots do anything?

If not, post the DC voltage on all terminals of the LM339.

 

[imraneesa]

I've never seen clean audio pass with no bias for the differential amp. Do the bias pots do anything?

If not, post the DC voltage on all terminals of the LM339.

There is nothing happening when bias pot is turned. here are the voltages;
Pin1 20.1v
Pin2 4.6v
Pin3 11.7v
Pin4 0.3v
Pin5 2v
Pin6 4.9v
Pin7 4.9v
Pin8 3.9v
Pin9 4.9v
Pin10 4.9v
Pin11 7.3v
Pin12 0v
Pin13 4.6v
Pin14 4.6v

 

[Perry Babin]

DC voltage on all 3 legs of Q10 and Q11?


Set the bias pots fully CCW so the bias won't be too high when the bias is restored to the differential amplifier.

 

[imraneesa]

DC voltage on all 3 legs of Q10 and Q11?


Set the bias pots fully CCW so the bias won't be too high when the bias is restored to the differential amplifier.

Q10
pin1 0v
pin 2 20v
pin3 0v

Q11
Pin1 0v
Pin2 -20.2v
pin3 0v

 

[Perry Babin]

It looks like Q10 has bad connections and may be defective. The collector should be at about 15v. The base is at 20. That should make the emitter about 1/2v below the base.

 

[imraneesa]

It looks like Q10 has bad connections and may be defective. The collector should be at about 15v. The base is at 20. That should make the emitter about 1/2v below the base.

lm339 pin1 was 20v now i am not getting 20v on pin1 again. R37 has 20v on one side other side is 0v.

 

[Perry Babin]

The 20v side of that resistor should connect to the collector of Q10. Find the break between them.

 

[imraneesa]

The 20v side of that resistor should connect to the collector of Q10. Find the break between them.

pin 7 of lm393 is 0.7 and so pin1 is pulling low so there is no voltage on base of Q10.

i dont know how pin 7 was showing 4.6v before and pin 1 was 20. that may be for some intermittently showed correct. now actually lm393 pin7 is 0.7v and pin 6 is 4.6v.

 

[Perry Babin]

One thing at a time. Why doesn't the collector of Q10 have 20v?

See attached.

 

[imraneesa]

One thing at a time. Why doesn't the collector of Q10 have 20v?

See attached.

yes the collector of Q10 is having 20v.

 

[Perry Babin]

Earlier, it was 0v. What happened? This has nothing to do with the voltage on the 339.

 

[imraneesa]

Earlier, it was 0v. What happened? This has nothing to do with the voltage on the 339.

collector is connected to 20v straight that is what i mentioned when i posted voltages for Q10. pin2 is the top pin among three pins i assumed. so collector was pin 2.

i should have mentioned base collector and emitter instead pin1 pin 2 and pin3 which confused. sorry for that it was my fault.

 

[Perry Babin]

Th collector is pin 3.

OK. Re-post the voltage on the 339 if the voltage has changed.

 

[imraneesa]

Earlier, it was 0v. What happened? This has nothing to do with the voltage on the 339.

Thank you for the schematic diagram sir. C5 was bad as soon as i changed it Bias start to work and i am getting super power. that was really strange problem and without you i would have take days to find that. Thank you very much.

 

[Perry Babin]

I'm sorry that we went around the scenic route but the clean audio on the output had me chasing signal level issues instead of muting problems. Generally, there is absolutely no audio before the bias for the differential amplifiers is enabled.