To clarify, if the oscillation is delayed, the amp powers up normally and if it starts immediately, the output section draws current. Is that correct?
Yes Perry, If the oscillation is delayed the amp powers up normally. If the oscillation starts immediately, the output section draws current.
Okay, three of the amp channels are running. The fourth, U7, is running but causing a fast ticking/popping sound in the output. I changed the driver chip again to make sure it wasn't damaged. Same result. Any ideas?
Last edited:
I did. Twisted on it. Pressed and tapped with a rubber mallet. No change. I can pull the outputs on that amp and the other three are clean. With out the outputs, drive looks good.
Try this. Remove the outputs from that driver group and connect the input of that inductor to the input of one of the working inductors with a 2 ohm dummy load. Does that cause any problems?
Does the signal look the same on the input to all 4 inductors?
Did the current draw increase when the 4th inductor was connected?
Did the current draw increase when the 4th inductor was connected?
No increase in current draw.
Signal is a little different. The square wave has taller peaks on the left side of the wave. other than that equal. Do you need a pic?
Signal is a little different. The square wave has taller peaks on the left side of the wave. other than that equal. Do you need a pic?
If nothing changes when you twist the inductor, I'd think that the problem is in the drive of the FETs.
Peak to peak voltage is different. 38v on the three good inputs. 54v on the one I jump the good input to.
Just tried wiggling it again. Twisted pretty aggressively. No change. No increase in current draw.
The problem may be the dummy load resistor. Do you have a significantly lower value resistor that you could try? You can go direct intermittently (at first) to see if it's still OK.
Lower value didn't change. Ran it direct intermittently, didn't change. Still 54v peak to peak compared to 38v on the other three. No noise. Runs fine.
I have a Digital Design amp here that uses the same driver board. I guess I can repair it and try the board in this one. That would at least tell me if it's on the driver board. Maybe a bad high or low-side output cap?
I have a Digital Design amp here that uses the same driver board. I guess I can repair it and try the board in this one. That would at least tell me if it's on the driver board. Maybe a bad high or low-side output cap?
I did Perry. Put a jumper across the load resistor. Signal looks like the other three inputs. The peak to peak voltage is different. I don't know why or if that is an issue.
I was just speculating on the high/low side output caps on the driver board. Just wondering if one of them could cause the noise on the output. That is all. Just disregard that.
I was just speculating on the high/low side output caps on the driver board. Just wondering if one of them could cause the noise on the output. That is all. Just disregard that.
What I meant by didn't change in post #76 was no noise. still playing clean. The signal did change. It looked like the other three. Sorry for not being clear.
How can the voltag across the inductor be different if it's directly connected to one of those 3 inductors.
The output caps are beyond anything high or low. The output caps are essentially across the speaker terminals.
If the inductor isn't causing problems when directly connected to one of the other inductors, the problem is likely in the drive circuit.
The output caps are beyond anything high or low. The output caps are essentially across the speaker terminals.
If the inductor isn't causing problems when directly connected to one of the other inductors, the problem is likely in the drive circuit.