thepraqtice
Member
- Joined
- Dec 4, 2012
- Messages
- 18
Either faulty right side audio-VCA or a solder bridge at the VCA on pcb. You could confirm this by swapping left side with right side audio-VCA. With faulty VCA, distortion will follow the faulty part. Distortion still at right side, use a magnifying glass to spot and remove the solder bridge.
I tried swapping VCA's and distortion stays on same side. Then tried looking for solder bridges and couldn't find any. Tried resoldering all points around VCA's and opamps with a very small soldering iron tip and went light on solder to avoid bridges. Distortion is still there as before.
If I take out right VCA with no jumper, just leaving left VCA in and send a mono signal through both inputs the output level is about equal on both L+R outputs with no distortion... If I take out the left VCA with no jumper, only leaving right VCA in. I have about the same amount of signal as before on the right output with no distortion, but no signal at all through the left output.
I pulled out both VCA's again and replaced with jumpers again and it seems like I must have missed this the first time. With a mono test tone the signal on the right side is significantly higher than the left signal although there is no saturating distortion which I presume must be the VCA's overdriving/saturating from signal being too high on right side before it goes through the VCA's...
I checked again with jumpers. A hard right panned signal only comes out of right output and a hard left panned signal comes out of both left and right outputs. the right out even seems to be a bit higher than left output with a hard left panned signal.
I tried swapping input opamps, no change. Switched opamps in VCA section, no change. Swapped output opamps and still no change of sides.
Very confusing. Do you think the left signal must be bleeding into the right channel somehow and the addition of the extra left signal going through right is making VCA's saturate on right side? Presumably this is happening before the VCA's, so maybe somewhere in the input section? If so it's seems like it's well connected... :-\