Rockford 400a4 problems

elvisjer · 1st October 2008, 04:14 PM

Hello everyone, im the n00b here! I searched and was sent here from DIY mobile audio forums. To make it short, i bought a Rockford 400a4 amplifier used and it is having some problems. It's near mint in physical condition and the board inside appears totally clean. Two of the 4 channels are very dirty, noisy, and just plain broken sounding. This really makes the amp un-usable. Im familiar with working on electronics but not with amplifiers. I searched the net and found a couple other people saying they have had similiar problems with thier 400a4 amps. Someone said, "Dr Fosgate" would help me here... ANyone have a good starting place?

Perry Babin · 1st October 2008, 05:07 PM

Do you have access to an oscilloscope?

Are any of the 8-legged op-amps getting hotter than the others?

With no RCAs plugged into the amp, what is the resistance between the shields of the front and rear inputs?

Is the distortion affected by the position of the switches or the potentiometers?

I don't have the schematic for this amp. If you get one from Rockford, it will make troubleshooting easier.

elvisjer · 1st October 2008, 08:32 PM

I do have an oscilloscope indeed. Ill run some of those tests after school. Thanks!

niteowl · 2nd October 2008, 03:31 AM

Hi Elvisjer

Send me your e-mail address and I'll send over a copy of the schematic to your e-mail. That should help your quest.

Martin

1st October 2008, 04:14 PM	#1
elvisjer diyAudio Member Join Date: Oct 2008	Rockford 400a4 problems Hello everyone, im the n00b here! I searched and was sent here from DIY mobile audio forums. To make it short, i bought a Rockford 400a4 amplifier used and it is having some problems. It's near mint in physical condition and the board inside appears totally clean. Two of the 4 channels are very dirty, noisy, and just plain broken sounding. This really makes the amp un-usable. Im familiar with working on electronics but not with amplifiers. I searched the net and found a couple other people saying they have had similiar problems with thier 400a4 amps. Someone said, "Dr Fosgate" would help me here... ANyone have a good starting place?

1st October 2008, 05:07 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have access to an oscilloscope? Are any of the 8-legged op-amps getting hotter than the others? With no RCAs plugged into the amp, what is the resistance between the shields of the front and rear inputs? Is the distortion affected by the position of the switches or the potentiometers? I don't have the schematic for this amp. If you get one from Rockford, it will make troubleshooting easier. __________________ 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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1st October 2008, 08:32 PM	#3
elvisjer diyAudio Member Join Date: Oct 2008	I do have an oscilloscope indeed. Ill run some of those tests after school. Thanks!

2nd October 2008, 03:31 AM	#4
niteowl diyAudio Member Join Date: Sep 2005	Hi Elvisjer Send me your e-mail address and I'll send over a copy of the schematic to your e-mail. That should help your quest. Martin

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