Vfl 22k #2

[mnhiphop101]

the amp has an issue where it plays audio fine at 12 volts but at 14 volts the audio cuts out. When I was poking around I noticed the 7912 regulator is only putting out -7.7 volts. Im having trouble figuring out why. I replace the regulator with no change

 

[Perry Babin]

What's the input voltage to the regulator?

 

[mnhiphop101]

So the amp power up fine. All rail voltages are correct but I'm not getting any switching and I can't figure out why.

 

[Perry Babin]

Is the drive signal reaching the gates of the output FETs?

 

[mnhiphop101]

No, I was unaware that I would be able to get signal on the gate without switching.

 

[Perry Babin]

Are you getting the drive signal to the input of the driver IC?

 

[mnhiphop101]

No

 

[Perry Babin]

Are both of the SMD ICs original?

I can see that one is a TL072. What is the other?

 

[mnhiphop101]

So I got this amp playing audio but only at low levels. As soon as I turn the gain up the wave shape distorts.

 

[Perry Babin]

Does the rail-rail oscillation still drive to the rails when the amp distorts?

 

[mnhiphop101]

Yes

 

[Perry Babin]

Does no load or loaded make a difference?

Before installing the outputs, did you check for the proper operation of the TL072? I've never done it on this board but connecting a 10k resistor across terminals of 1 and 2 (or 6 and 7 if they're using the other half of the TL072) should tell you if the TL072 is working properly.

You have a badly damaged via (can be seen in the original post).

Is the drive good out of the LM211 going from 0% to 100% duty cycle when driven hard?

 

[mnhiphop101]

The signal going into the irs2184 is clean. Would 2 lightbulbs in series be a good enough load?

 

[mnhiphop101]

Can I use the neg terminal as ground to measure the duty cycle?

 

[Perry Babin]

You will have to use your scope. Letting the scope ground through the 12v power supply ground should be sufficient. If it's too noisy, use the secondary ground.