Rockford Fosgate type RF X7

[seankane]

Hello all, I have RF X7 board number PC-3758-H

The amp powers up and idles fine, no DC on output terminals, and is not in protect.

I tested for output and the output is very low and viewing it through the scope it is low as well and intermittant. I messed with the gain knob and it spikes to full rail on the output terminal when turning the gain pot and the gain pot does not increase the output.

I am going to switch out the gain pot to a new one but my question is, could the pot being shorted or bad cause this symptom or is there something else I might look over as well?

 

[Perry Babin]

Look at the preamp level signal before it gets to the amplifier section to see if it's good or bad at that point.

 

[seankane]

OK well if I switch the infrasonic switch it puts over 100 vdc to the output terminals and kicks the protect.

So far I have changed the infrasonic switch and the gain pot.

Why would the infrasonic be putting so much DC on the output terminal?

 

[seankane]

Pic #1 of main board and #2 the little control board on which I think the problem is?

 

[Perry Babin]

I would suspect an op-amp with DC on its output.

 

[seankane]

Did you read post number 3?

I am suspecting an op-amp as well, just wanting to make sure you read post #3 as well.

 

[seankane]

OK Perry bare with me here I have been attempting to read schematics again.

U2 and U3 have 11 vdc on their outputs.........so...............

Signal enters U1 from pins 2&3 and 5&6, then leaves U1 througn pins 1&7 which have no DC.

Enters U2 pins 2&3 out pin 1 to pins 5&6 then out pin 7.

U2 has 11 vdc on pins 1&7

Enters U3 pins 2&3 leaves pin 1 to pins 5&6 then out pin 7.

U3 has 11 vdc on pins 1&7

Enters U4 from there and U4 has no DC on output pins. So switching the infrasonic switch must enable or bypass U4 depending on switch setting?

If U4 is bypassed the switch would send DC from U2 and U3 to where ever it goes next. If U4 is enabled, why is it not getting the DC from the output pins on U3?

Where is the 11 vdc coming from on the output pins of U2 and U3?

 

[seankane]

Please read post #7 first.

I replaced U2 and U3 the amp works great, but if its not to much trouble could you give a few answers fro, post 7? Was I close on reading the schematic?

I cannot believe how much power this amp has.......its like WOW!!!!

Looks like an over glorified 1500BD to me but I can sure tell a difference in output....WOW!!!!

 

[seankane]

Dont forget to read post #7 and #8 Perry!!!

This thing is a beast people, you would not believe the power this thing has, I am truly impressed. I have been around alot of amps and most of what I hear is what I expected but not with this one.....I was OMG!!!!


Thanks for the help Perry.

 

[seankane]

You will have to excuse the crappy picture the lighting was horrible and flash made a wierd reflection off of the chrome.

Look at the size difference between the X6 and X7. I thought the X6 was big. The X7 dwarfs a BD1500!!!

 

[warpedhifi]

You got me curious enough to look up the specs on that amp, that amp is rated at 650 watts x 1 at 4 ohms and 1300 watts x 1 at 2 ohms. Sounds like you have a nice monster on your hands. You keeping it or selling it, or was it a customers???

 

[seankane]

Those are the specs for the X6 the X7 specs are much higher. Im not sure what I am doing with it just yet.

 

[seankane]

http://www.rockfordfosgate.com/rfte...FbdAmps-MAN.pdf?AspxAutoDetectCookieSupport=1

These are conservative ratings, I have read people have done testing and seen over 1800 watts rms of pure clean efficient power!!!

 

[warpedhifi]

Ok, did not see that, The one I was looking at was the RF X7, from 2002, the one you posted was for a RF X7.A or X7.C from 2003. I did not know they had two different versions of this amp.

 

[seankane]

The only difference was gun metal finish and chrome finish, Rockford released very conservative ratings when these amp were first introduced but later revised their ratings to closer to what they actually put out.

The average birth sheet I have seen for these amp is between 1700-1900 watts.

 

[warpedhifi]

Ok, was not sure what the differences were, but now I know. Thanks for the info. Put that amp on your XLC 18 and see what it does.

 

[seankane]

I would be afraid for my XLC 18, I do have 2 power HX2 15's in a 7 cubic ft vented box that would love some juice like that!!!!

 

[shawnk]

I would be afraid for my XLC 18, I do have 2 power HX2 15's in a 7 cubic ft vented box that would love some juice like that!!!!

Now that would be freaky!

 

[seankane]

The box is a corner coffee table right now, I have nothing to put it in at the moment, it also weighs in at over 400lbs so its not very moveable by yourself. With the whole box being 1 1/2" thickness, all the bracing, the subs, the resin, the led lights, the custom binding posts, and the carpet it really got heavy quick!!!!

 

[shawnk]

Pics YO!