Since the antenna was just installed I'd look there. Are things hooked up
well at the antenna? Are you using the right cable? Is there a strain relief
on the downlead, how about some mast standoffs? Ok, we're in the house, do
you have a good connection to the signal splitter? Do you have good
connections from the splitter to the converters?
Just take it by the numbers, one step at a time, and check the antenna
install. Since one tv works I'd bet the problem is with the connections at
the signal splitter or the cable from the splitter to the converter is bad