Rockford Fosgate Punch 250M

[seankane]

C108: -0.064 vdc
C110: -15.41 vdc

 

[Perry Babin]

Post the DC voltage on all pins of U102.

Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

 

[seankane]

Post the DC voltage on all pins of U102.

Pin 1: -15.47
Pin 2: -9.74
Pin 3: -9.74
Pin 4: -17.41
Pin 5: -9.46
Pin 6: -9.46
Pin 7: -15.02
Pin 8: +27.08

 

[Perry Babin]

What is the DC voltage on the RCA shield?

Make sure that the shield connections are intact.

 

[seankane]

0.013 vdc

 

[Perry Babin]

Find R115. Do you have -10v on one end and 0v on the other end of it?

 

[seankane]

yes

 

[Perry Babin]

Check the components around Q12 (the +15v regulator). If they're within tolerance, post the voltage on all 3 legs of that regulator.

 

[seankane]

R33 was out of tolerance i changed it.

The regulator reads as follows:

Vin: 29.24
Vout: 17.53
adj: 16.27

 

[Perry Babin]

With all of the components in the circuit, do you still have DC offset on the outputs?

 

[seankane]

Its strange right now I have no DC on the output but if I touch a dummy load the DC increases and I still have no output. If I touch my scope lead to the + terminal its really hazy like there is dc.

 

[seankane]

Ok wierd when I switch the l+r or l mono switch the amp shows output but slightly distorted. As I increase the volume R329 starts sparking on the board???

 

[seankane]

I have found a broken trace from the positive speaker terminal then to the pad of C122 and from there to R191. Could this be the whole issue?

 

[Perry Babin]

Does it have a bad solder connection?

 

[seankane]

post #33 please read

 

[Perry Babin]

I don't see R191.

You posted while I was typing. I left it. I didn't see any point in deleting it.

 

[seankane]

Here is a pic of the broken trace I think thats what was sparking under the other components, you can see now that I removed the components.

 

[seankane]

did you look at the pic I posted?

 

[Perry Babin]

I don't see R191 on the diagram. It may have been omitted.

If the Zobel network R329 and C122 are out of the circuit (broken trace), that could cause some noise issues.

Does the noise subside when you repair the trace and connect a speaker?

 

[seankane]

I will repair it and let you know, R191 is in the pic and it had a 1000 ohm resistor in place before I removed it. All of the bare pads in the pic had resistors in place except for C122 of course which had a ceramic capacitor. R191 was marked 103 which should be a 1000 ohm correct?