The system took a lightning strike a couple of weeks ago that re-set programming to default and took out the maintenance port.
I replaced the DXCPU and was able then to get into the program mode and restore program from backup.
After doing this I found that several exts. had distorted transmission on handset and speakerphone. All of these exts. were on the same DXDST-16 card which is in UNV slot 6 of the expansion cabinet. I have verified that the problem is in the KSU and not the cabling. I have replaced the DXDST-16 card but that did not clear trouble. All of these are in a remote building that was closest to the lightning strike. I have replace surge protection on both ends of cable since I found a couple of bad protectors that had 2 stations totally dead.
I suspect one or both of the interface cards. Any suggestions? Thanks!

I would suspect the DXSRV (services board), on first instinct, based on what you described.

Have had same problem and chased it for weeks. If what Justin suggested doesn't work and you have a DXAUX board in the system remove it and check for noise.

Hmm. Interesting thought, Dlr920.

I wonder if there's any chance of my recent, similar problem on an FXT being a bad MAUX board. I don't know I've run across a situation where the AUX board has also gone bad, along with the two others (CPU and SRV).

Justin