Rockford Fosgate Power 1000a2

seankane · 5th April 2011, 02:56 AM

Hello again Perry. I have a rockford power 1000a2 that is doing something I have never encountered before. The board number is a PC-2392E.

The right channel never had any sound when I recieved the amp about 5 years ago. Since then I have come along way in my repairs, so it was sitting on the shelf collecting dust and I kinda just found it again.

I replaced all the output fets in the right channel years ago and never went any further. The left channel has great sound. The right channel has great sound for about 3 seconds then just fizzes out to nothing at all. Amp idles fine no current issues. Can I get a heads up on where to start??

seankane · 5th April 2011, 03:01 AM

I must add the right channel will not bias either.

Perry Babin · 5th April 2011, 03:13 AM

Drive a sine wave into the amp with a speaker (or dummy) load on the right channel. Snap a photo at the point where it begins to fade out.

seankane · 5th April 2011, 03:21 AM

Ok I will try but it happens so fast. I hear the sine wave clear and loud for a few seconds then it gets real quiet. You can still hear the sound but at very low volume. No matter how loud you turn the volume it just stays at the same low volume. Does not sound distorted either, just really quiet. If you turn the amp down then back up it is loud for a second or 2 then like someone is turning down the volume. Like waiting for a cap to charge then discharge ya know? I will try my best to snap a pic. Scope settings? 5vol/div 5 us ?

Perry Babin · 5th April 2011, 03:24 AM

I guess I didn't understand 'fizzes out'. I would have expected distortion. If it's not distorted, don't worry about the photo.

Perry Babin · 5th April 2011, 03:27 AM

Check the signal level on the positive terminals of C304 and C201. Do they remain the same when the output drops on the right channel?

seankane · 5th April 2011, 03:28 AM

Sorry I should have been more clear.

seankane · 5th April 2011, 03:32 AM

Ok I will have to pull the board from the sink to get to the + terminals of those 2 caps. Give me a liitle bit, lotta screws to pull

seankane · 5th April 2011, 03:45 AM

No the signal does not change only in amplitude as you increase the volume. Both sides look identical, when the sounds drops off with a speaker connected and without a speaker connected. The signal is different from idle to volume but I think its just amplification. Would you like a photo of idle and volume output on the scope from the positive terminals from those two caps???

Perry Babin · 5th April 2011, 04:01 AM

You should have asked if you could use a different test point.

Are you saying that, at that point, the signals remain identical in amplitude at those caps both before and after the signal drops on the right channel?

5th April 2011, 02:56 AM	#1
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Rockford Fosgate Power 1000a2 Hello again Perry. I have a rockford power 1000a2 that is doing something I have never encountered before. The board number is a PC-2392E. The right channel never had any sound when I recieved the amp about 5 years ago. Since then I have come along way in my repairs, so it was sitting on the shelf collecting dust and I kinda just found it again. I replaced all the output fets in the right channel years ago and never went any further. The left channel has great sound. The right channel has great sound for about 3 seconds then just fizzes out to nothing at all. Amp idles fine no current issues. Can I get a heads up on where to start??

5th April 2011, 03:13 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Drive a sine wave into the amp with a speaker (or dummy) load on the right channel. Snap a photo at the point where it begins to fade out. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

5th April 2011, 03:24 AM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I guess I didn't understand 'fizzes out'. I would have expected distortion. If it's not distorted, don't worry about the photo. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

5th April 2011, 03:27 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Check the signal level on the positive terminals of C304 and C201. Do they remain the same when the output drops on the right channel? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

5th April 2011, 04:01 AM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	You should have asked if you could use a different test point. Are you saying that, at that point, the signals remain identical in amplitude at those caps both before and after the signal drops on the right channel? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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5th April 2011, 03:01 AM	#2
seankane diyAudio Member Join Date: May 2010 Location: Washington State	I must add the right channel will not bias either.

5th April 2011, 03:21 AM	#4
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Ok I will try but it happens so fast. I hear the sine wave clear and loud for a few seconds then it gets real quiet. You can still hear the sound but at very low volume. No matter how loud you turn the volume it just stays at the same low volume. Does not sound distorted either, just really quiet. If you turn the amp down then back up it is loud for a second or 2 then like someone is turning down the volume. Like waiting for a cap to charge then discharge ya know? I will try my best to snap a pic. Scope settings? 5vol/div 5 us ?

5th April 2011, 03:28 AM	#7
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Sorry I should have been more clear.

5th April 2011, 03:32 AM	#8
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Ok I will have to pull the board from the sink to get to the + terminals of those 2 caps. Give me a liitle bit, lotta screws to pull

5th April 2011, 03:45 AM	#9
seankane diyAudio Member Join Date: May 2010 Location: Washington State	No the signal does not change only in amplitude as you increase the volume. Both sides look identical, when the sounds drops off with a speaker connected and without a speaker connected. The signal is different from idle to volume but I think its just amplification. Would you like a photo of idle and volume output on the scope from the positive terminals from those two caps???

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