I have a Sub amp, with burned resistors. The owner mixed positive an negative , so the remote circuit was burned. Thats allready fixed. But on the preamp board are two resistors burned, and i can not recognize the value. The amp play disorted, if i connect an input from my home amp, i have strong ground noise. Also the output, if i connect a signal generator, i have strong disorted signal. Maybe somebody can give me the values?
Are there any diodes in the input circuit that are shorted?
If the resistor burned from 12v being reversed, it's likely a low value.
If the resistor burned from 12v being reversed, it's likely a low value.
Still working on this amp. Maybe someone can calculate r 815. See diagram attached.
The sinewave on this amp is changing the amplitude. Makes strange noise. I think this is a feedback circuit, op amp jrc 062 controlling the positive and the negative half of the sine.
The sinewave on this amp is changing the amplitude. Makes strange noise. I think this is a feedback circuit, op amp jrc 062 controlling the positive and the negative half of the sine.
Attachments
Still working on this amp. Maybe someone can calculate r 815. See diagram attached.
The sinewave on this amp is changing the amplitude. Makes strange noise. I think this is a feedback circuit, op amp jrc 062 controlling the positive and the negative half of the sine.
The sinewave on this amp is changing the amplitude. Makes strange noise. I think this is a feedback circuit, op amp jrc 062 controlling the positive and the negative half of the sine.
The missing resistor could be the same value as R811. I’m guessing this based off of your drawing. I would try that and see if your problem gets resolved.
David
David
I don’t get why you needed the vale of R815 in your first pics R815 was in place then it was missing in your last post and you were asking for the value .
The resistor in the photo at r815 is 22k. He may have put that resistor in place thinking that’s what went there, not knowing for sure because he stated the original resistor was burned. At least, that what I assumed.
The resistor at r811 is 220k.
Since he is dealing with the inverting and non inverting outputs of the op amp I would think you would want them to be balanced since the circuit is the same for both outputs.
I figured that was the reason he was getting the distortion. I would think if he looked at it with a two channel Oscope he would have seen an unbalanced sine wave or square wave.
The resistor at r811 is 220k.
Since he is dealing with the inverting and non inverting outputs of the op amp I would think you would want them to be balanced since the circuit is the same for both outputs.
I figured that was the reason he was getting the distortion. I would think if he looked at it with a two channel Oscope he would have seen an unbalanced sine wave or square wave.