On Aug 20, 1:02 pm, z wrote:
got an old..... Sony Trinitron. electronic tuning, so it's not that
old, but mono. switched to CATV input, it gets (analog Comcast)
channels 2-40 perfectly, gets nothing from 41-99. Now that's just too
clean a break to be anything other than design, so does anybody know
what gives?

What gives is that your TV tuner was designed for an earlier era.
There have been at least three generations of "cable-compatible"
frequency sets, and your TV evidently can't see whatever set your
cable uses. Are you sure your TV tuner is set to "CATV" or "CABLE"
versus broadcast?

There used to be little boxes available that could block-translate
frequencies...call the cable company and ask about a "block converter"
for your set.