Rockford Fosgate Type RF X6

[Perry Babin]

Can you see a way to break the connection between pins 1 and 2 of the 339 (without lifting them from the board) and pin 8 of the SG3526?

 

[seankane]

Not without breaking a trace.

Do you still have this schematic?

 

[Perry Babin]

Yes. Why? Does it appear that I'm cluless?

 

[seankane]

No lol......pins 1 and 2 are connected by a trace R80 is connected to them but goes to pin 5.

Pin 8 on the 3526 is fed by the pins 1 and 2 of the 339?

Is it possible the 3526 is defective?

The output pins of the 3526 feed the drivers for the power supply and that why the drive signal doesnt look good because the drivers are not sending a signal to the power supply fets because they are not receiving one correct?

I removed the jumper wire and the capacitor and the amp is not drawing any current but is making all kinds of noise now.

I removed all the mods from the last X6 chrome I repaired without any issues.

 

[Perry Babin]

I don't see anything connected to pins 1 and 2 that could be preventing it from being pulled up by R19. If you could disconnect pin 8 of the 3526, that would help confirm that the 3526 is defective. The fact that the 5.1v output is low is another concern.

You could try jumping pin 8 to pin 18 to see if that would allow the amp to power up.

 

[seankane]

When all the mods were removed it sounded like the squeeling was coming from the U21 hard to tell though.

I replaced U21 and the amp powers up and produces a square wave and about 90v rail and has audio.

The gate signal still looks funny though what do you think?

 

[Perry Babin]

I think the gate signal is OK.

U21 doesn't affect the power supply. It shuts down the audio circuit.

 

[seankane]

Ok why when I replace U21 the amp now powers up like its suppose to and protect goes out after a few seconds now?

 

[Perry Babin]

I don't know. If it appears to be repaired, test it thoroughly.

Did the DC voltage on pin 18 come up to 5v?

 

[seankane]

Pin 18 is 5.00 vdc exactly.

The output is a little distorted, I think I have a bad opto-coupler. I have a square wave on pin 2 of U9 but its funny looking coming back out on pin 7 to the driver.

What do you think?

 

[Perry Babin]

It's not always easy to determine if the signal is good because it's floating. You have to use the scope in differential mode and place the probes on pins 1 and 3 of the output (without slipping and blowing them out).

I think that U21 was pulling pin 18 down and that was causing the problem (if that was indeed the problem). I've seen U21 leak plenty of times from pin 6 to the negative supply pin but never from pin 5 to the negative supply pin.

 

[seankane]

Changed the opto-coupler and the driver for good measure. I also had to replace the infrasonic and phase switches.

The amp sounds great, but cant load it hard until tomorrow, little one sleeping.

Thanks Perry.

 

[seankane]

I ran the amp hard and punished the old 18" xlc and I noticed the output of the amp going up and down on its own. I found when I pushed on the cross over pot and the gain pot it got alot louder.

I replaced both pot and this amp pounds something fierce!!

I ran it for about 30 min with no issues. Didnt even get remotely warm to the touch either.

Thanks again for the help.