On Jul 8, 7:40*am, "William Sommerwerck"
wrote:
One other point...

I believe a Trinitron has a single cathode. It's possible the cathode's
emission has fallen to the point where you can't get a picture.

No - separate cathodes. I'm not sure, but I think the "one gun"
description covers it's single focus element. It's possible that he
has a red cathode failure. If the OP has access to a CRT tester,
Trinitrons are checked in the same manner as any color CRT.

OP should reflow the CRT board and flyback, and check solder on all
the TO-220 regulators he can find. After that, it's tracing with a
scope.