Picture: Scope setting 0.2 V/div 0.5 us
#1 is C412
#2 is Ch3 Drain FET
#3 is Ch1 and Ch2 Drain FET
Ch 4 oscillation does go away with load.
Yes Channel 4 is the only one with oscillation like Pic 1 in #159
#1 is C412
#2 is Ch3 Drain FET
#3 is Ch1 and Ch2 Drain FET
Ch 4 oscillation does go away with load.
Yes Channel 4 is the only one with oscillation like Pic 1 in #159
Attachments
I wouldn't expect to see DC on the capacitor.
Do all channels on Cx12 have that same DC, at the same voltage, on both terminals? Use a multimeter. No waveform necessary.
Do all channels on Cx12 have that same DC, at the same voltage, on both terminals? Use a multimeter. No waveform necessary.
Capacitor xxx: +/- terminals of capacitor in that order, Vdc:
C412: 0.648/-0.038
C314: 0.648/-0.040
C212: 0.653/-0.043
C114: 0.629/-0.034
C412: 0.648/-0.038
C314: 0.648/-0.040
C212: 0.653/-0.043
C114: 0.629/-0.034
With all being the same, It's OK. I think that grounding the RCA shields would bring the 0.6v down.
I think it was on this thread...? The problem may be due to the layout of the board, assuming that all of the components in the board, for all channels, are the same (assuming that there was no manufacturing defect in placing the parts).
There may be a solution like changing the value of a capacitor, somewhere in the circuit, but that would be time consuming. If the oscillation doesn't exist with a load, it may not be a problem that needs to be resolved.
There may be a solution like changing the value of a capacitor, somewhere in the circuit, but that would be time consuming. If the oscillation doesn't exist with a load, it may not be a problem that needs to be resolved.
I realize that this amp is likely gone but if not, look at this post and the threads before it:
https://www.diyaudio.com/community/threads/rockford-punch-600-a4-noise.387075/post-7044844
https://www.diyaudio.com/community/threads/rockford-punch-600-a4-noise.387075/post-7044844