personally i'd look at checking out any op amps etc in that particular circuit after it branches off - could also be a bad joint or flakey/noisy resistors or caps... here's a pretty cool little project to scope such things out.Troubleshoot Electronics FAST with a Super Probe Troubleshoot Electronics FAST with a Super Probe Build a "Carlson Super Probe" and make your electronic troubleshooting easier. Locate noisy parts fast! This is a "non-contact" style probe that... View on www.youtube.com Preview by Yahoo