RCA XL100 portable with a dark screen

[zeno]

The part is a coil.
Try adjusting the G-2 control.
Measure G-2 use a meter good to 1KV. Normal is abt 400VDC.
Measure the cathodes. If they are up to 200 VDC the set
has a video problem. If apx 120-150 VDC video is normal.
Longshot, pull & check the CRT socket for overheating. Some
early RCA in lines would get a poor fillament connection.
Last is a dead CRT, more on that later.......

73 Zeno
LFOD !