Rockford Fosgate P500-2
 

Hello I have a newer P500-2 that Rockford wont release the schematic to yet.

One channel has distortion, any idea where to look? Maybe the A/B driver card?

I posted a pic of the board, it is number 1325-52756-02 2007 model.

The wierd thing is the output on the scope with a 100Hz sine wave scope set at 2ms 20v/d the output looks clean.

When you play a music cd the amp plays ok for a little bit then as the volume is increased the amp cuts out with the red and yellow lights clipping on and off. When the volume is decreased then the channel gets distorted.

I dont understand why it is clean on the scope??????

Any ideas????

I haven't had to repair many of the amps of this type. The only fault that I found was as indicated in the attached image. The fault may be related if the transistor is leaky.

There can be different types of distortion. Not all are as easy to see as clipping or severe under-biasing.

I will check it out. It seems to only have distortion with a load. It looks clean on the scope.

There is no DC on either bridging terminal.

As a side note, these daughercards appear to be used in a *bunch* of the newer style amps, I am pretty sure i've seen this same part number in the p300-1, p300-2,p400-2,p400-4 and p500-2, and I'm pretty sure even the power series t600-2/4 amps too...

@sean,

I'm having similar distortion on a p300-1 amp. what did you find to be defective on the 500-2?

@ PB,

What is the correct testing procedure for the smd transistor as noted below and in the attached photo?

Ps. I don't have a scope.
http://www.diyaudio.com/forums/attac...6-see-note.jpg

On that amp, the transistor was shorted. If you find a direct short between any of the legs of that transistor, it's defective. If it's leaking, you'd have to lift two legs or remove it for testing.

I never went any further on the amp, the customer is in no hurry and I have so many to repair I put it on hold. I will likely pick it up in the next few days, I am trying to get this tiresome punch 800.2 fixed its really wearing me thin!!