Rockford Fosgate Power 360a2

[seankane]

I do have audio there but they are different looking signals. Q202 looks like the input. Q203 looks like the input, but instead of having a straight line in between cycles its really wavey. Q202 has a straight line in between cycles. If this does not make sense I can post a pic.

 

[Perry Babin]

I don't think you should have audio on Q202 unless there is more than about 1/2v DC difference between the bases of those two transistors.

Is the DC between the bases essentially the same (within 0.01v)?

 

[seankane]

Q202 base reads: -0.091 vdc

Q203 base reads: -0.092 vdc

BLK PRB amp ground

RED PRB each base

 

[seankane]

I was using the 100Hz sine wave as audio should I be using something different?

 

[Perry Babin]

Is the audio you see roughly the same amplitude on both ends of R216?

 

[Perry Babin]

100Hz is OK.

 

[seankane]

Something I wanted to add was that when I touch my scope lead on the bridging terminal of the faulty channel it looks exactly like the input, only it does not amplify when the volume is increased it remains as if idle.

 

[seankane]

R216 looks like the same signal I am seeing everywhere else but one end of it deflects more than the other end.

 

[Perry Babin]

C211 shouldn't have signal on either terminal. If it has signal on one terminal but not the other, replace it.

I thought that you said that there was no output from the right channel? Did something change?

 

[seankane]

There is no audible audio from the channel. When I touch my scope lead to the bridging terminal, the signal looks the same as the input signal from the RCA. When you increase the volume on the head unit the signal does not change like the other channel. It stays like the input signal and does not amplify or change.

 

[Perry Babin]

Post a photo of the signal that you're seeing that doesn't change in amplitude when you change the volume. Also post one from the working channel.

Does the signal level change as it should at both C111 and C223?

 

[seankane]

I will post a series of pics. The first is input signal at idle, the second is the good channel at idle, and the third is the faulty channel at idle. Scope settings are 50m vol/div and 5us.

I will post signal the change in signal in the next post.

 

[seankane]

The signal changes at C111 as it should, but it does not change at C223. C223 looks just like the output signal of the faulty channel, just does not deflect as much.

 

[Perry Babin]

These are not audio. Re-check it with the scope set to 2ms.

 

[seankane]

I posted a pick of the good channel wave form. This signal is identical on both sides of C111 and changes as it should.

The faulty channel has no signal nor does C223, just flatline. Thats why I didnt post a pic dont really think its relavent.

Scope settings are 5 vol/div and 2ms

 

[Perry Babin]

Since you now know what you're looking for (the waveform seen above), do you have the same signal on the three op-amps I asked about previously?

 

[seankane]

Pin 7 of U201, U202, and U203 have no signal flat line wont trigger the scope.

 

[Perry Babin]

Do you have audio on pin 7 of U104 or on pins 1 and 7 of U201?

 

[seankane]

Do you have audio on pin 7 of U104 or on pins 1 and 7 of U201?

Pin 1 and 7 of U201 does not look like the input. Does not have a wavey form. If you turn the volume almost all the way up it just starts to get a tiny bit of wave to it but barely visible.

I dont find any U104 on the board.

U101 U102 U103

U201 U202 U203

These are the only ones I see.

 

[Perry Babin]

See attached