tv is samsung CB-5062 20 ". chassis seems to be an ONWA.

initial symptoms: dark picture with only blue on.

-lifted one end of the blue driver resistor away from the connection to
the cathode - still blue.

-connected output of the blue driver resistor with the red and vice
versa - no change.

-Tried isolating the filament by disconnecting the heater trace and
the ground next to it, then wrapping a couple of turns of wire round
the line output transformer - no change

-now with the heater isolated, if i disconnected the blue cathode from
its drive, there was no pic at all despite there being a glow

- looking closely at the crt neck, with all 3 colours connected and
heater isolated, only one filament appears to be lit. The focus and
screen controls also interact. seems like the tube has some multiple
problems. I've seen and dealt with many hk shorts and seen bad line
transformers with the focus-sceen shorted internally, but not these
symptoms together. I'd be curious to know if anyone has seen these
symptoms all together in one set before!!??
regards, -B