Skar Audio 4500.1D

[caraudioguy2100]

Wondering what is wrong with the drive circuit for 1 set of fets .

Here’s what I get on that bank .

Scope set to 10us 5volts/div

 

[Perry Babin]

It's likely OK but the trace wasn't aligned to the reference before the photo was taken.

 

[caraudioguy2100]

When that photo was taken the trace was centered before looking at the drive signal .

 

[Perry Babin]

How is it possible that the drive is going below ground?

 

[caraudioguy2100]

Not sure . This is where the line was set when I tested drive

 

[caraudioguy2100]

Ok i found the issue .

One of the buss bars was touching the tab of the NPN drivers .

Here is what I get now with the fets installed .

Scope set to 10us 5volts/div

 

[Perry Babin]

That looks better.

 

[caraudioguy2100]

Now i have a different issue with the amp .

The 12 volt regulators are working correctly .

The 15 volt regulators in only getting 3 volts out of both the 7815,7915

 

[Perry Babin]

Post a photo of the component side of the main board and the component side of any driver boards in the amp.

 

[caraudioguy2100]

I took the audio driverboard out of the amp just to be safe so I do t blow new outputs or driver ic’s while testing .

With the audio driverboard out of the amp I have the same issue .only 3 volts on both 15 volt regulators

 

[Perry Babin]

Measure the input and output voltage of the 15v regulators by placing the black probe on the ground terminal of the regulators.

 

[caraudioguy2100]

7915
Input:-4.93
Output:-4.26

7815
Input:4.74
Output:3.35

 

[Perry Babin]

What is the amplitude of the waveform feeding C53 and C54?

 

[caraudioguy2100]

First pic is C53 2nd pic C54

Scope set to 10us 5volts/div

 

[Perry Babin]

Scope settings?

That appears to be the output side of the caps, not the input.

 

[caraudioguy2100]

Scope settings are 10us 5volts/div

And here is what I get on the output side of the cap .

First pic is C53

 

[Perry Babin]

And at the input to the two green inductors?

 

[caraudioguy2100]

Sorry my mistake .

Scope settings are 10us 5 volts div .

Here is the output side of the caps

 

[caraudioguy2100]

Sorry been a long day .

Here is the output side of the inductors

Scope set to 10us 5volts/div

 

[Perry Babin]

The amplitude of the signal into and out of the caps should be the same. Try replacing them.