@stan2004 posted:Thinking: there is some evidence that TIU channels can lose signaling performance in some environments.
Actually Stan, there is a lot of evidence that the Rev. L TIU can indeed lose DCS signal strength in a number of environments! I had one that dropped to 25% of it's normal signal strength just being used on my test bench. I've repaired a host of TIU's for that very problem, it's actually quite common. The issue is the 74ACT244 IC used in the application with the gates are paralleled, a transient spike can zap one or more of the four paralleled gates and reduce the signal strength. Succeeding spikes apparently keep killing the gates one or two at a time until you don't have any signal. Truthfully, I think the parallel gates are a mis-use of the 74ACT244, I don't see any evidence that is accommodated in the design of the chip. MTH has even tried a couple of times to come up with a fix, and they've mis-fired both times.
