I have recently replaced a filter capacitor and power cord on a 1984 montgomery ward tv and it worked fine. After a while, it started doing this:

https://vimeo.com/332129517

Where would I begin to look at what's wrong with this? I have schematics available as well. Thank you!

Can't see the video ... It's a broken link.

Video is visible here. Is that arc inside the picture tube neck? Not a good sign.

That's a loud arc , if it's in the tube the gun may be finished, however, perhaps corona from dust and grounding to the yoke ?

It is difficult to tell from the video, but it looks like your crt may have lost vacuum.

Looks like the CRT. Only other thing is WAY too high focus voltage
but thats a one in a thousand shot.
Did the back get hit ?

73 Zeno:smoke:
LFOD !

Oh dear. That sure is inside the tube.

rip crt.

I mean I suppose some weird thing could be happening to make it arc like that. A short of some kind? More bad caps, maybe? idk.

Yeah, it definitely is inside the crt. I haven't bumped it or anything either. Like I said just replaced some stuff on the power supply. Could something have gone wrong there?

Just because you didn't bump it does not mean it does not have a leak or crack. A friend has a GE VIR set that had the same symptoms as yours (which would trip the HV shutdown), and was never bumped either...It was caused by a spontaneous fracture on the glass between the base pins.

Unplug the CRT base, power up and compare voltages to those listed in service literature. If none of them is better than %150 high then the electronics are probably fine and the CRT just lost vacuum from some defect in it's manufacture.