I have a system which was installed in 2001 with about 50 X10 devices. It worked almost perfectly except for a couple of duplex outlets being sporatic. I have since added several Switchlink devices 2476D, 2476S and most recently, a Carlon extend a chime. The flakey operation started this spring before the Carlon chime was added. It is getting worse. As part of the research, I tried to activate the various flakey switches by putting the comand controler at the same location as the switch and then the switch worked. I assumed line loss, resulting in signal loss, was the reason so I decided to replace the leviton 6299 coupler with an amplified one , ZPCI-B from Simply Automated. Same problem. The breaker panel has about 70 circuits total.
I originally purchased a power line signal analyzer, Monterey Instruments, and it works as advertised. When I read signal levels they appear to be attenuated sometimes to the limits of the analyzer and at that point they are ignored. Also sometimes the error code is identified as something like "spacing code error".
I adapted my scope to look at the power line and found X10 command signals in groups of 22 but the timing was such that the bursts occurred throughout the 60 Hz cycle rather than just at the zero crossing points of the 60 Hz. waveform. I thought they were always at zero crossing. I tried to turn off all X10 devices and observed the line noise and it was almost totally gone. Still the flakey problem persisted.
When I activate dimming controllers (which I have about 20 of) the line noise as seen on the scope is huge.
I originally purchased several noise filters but didn't put them on the system because the system worked fine without them. I'm not sure they will help since the problem perists even when all noisy switches are off.
The switches with the problem are Switchlink 2476D. One controls a water feature and the other controls landscape lights. They both worked fine for two years till now.
Thanks for any suggestions.
Jerry