Valentine's gift (or is it a shameless trick?)

[Phil Nelson]

Here's the victim.





Some of the layers under the doughnut had melted and sagged down so that you could just flick them off with a fingernail.

Should I try to melt off the old wax before recoating with RTV? Seems like I should at least reflow it with a heat gun so that it doesn't have big cracks.

The arc came out the side of the doughnut as seen in the second photo, going to the side of the cage. A very healthy spark! I'm not sure whether it came from the big crack seen in the first photo, or possibly from the nib where the rectifier lead enters the coil, since I only saw it for an instant.

If the cause of overheating is excessive HV, I'm not sure how to change that other than by modifying component values, as the set lacks a drive adjuster. After I noticed the vertical (drive?) line on the screen, I replaced the two 5% resistors (R83, R84) connected to the HOT input grid; both had drifted more than 20%.

My initial HV reading was a little low, about 14KV rather than the 16KV-18KV given in the schematic. That was before I recapped the sweep board and replaced a few resistors to address a vertical linearity problem. I hadn't tested the HV after that.

Unless someone has a better idea, I guess I'll recoat it, fire up the set again, and see what happens . . . .

Phil Nelson