Mind the gap! RCA 10BP4 failure

[Penthode]

Deleted post

[Tim Tress]

In almost 50 years, I have encountered two 10BP4s with the same problem; the filament lights, but there is absolutely no emission. Both were from late 1940s sets, so maybe there were some issues during manufacturing.

[Penthode]

Check the cathode connection in the tube. My observation is the cathode opening due to a burst of high current which is enough to melt the fine metal link to the cathode pin of the kinescope.

[Chris K]

I guess a gap of that size means it's hopeless to try to reweld the cathode using that function in many rejuvenators, even with vigorous shocking of the CRT neck?

[Electronic M]

Originally Posted by Chris K

I guess a gap of that size means it's hopeless to try to reweld the cathode using that function in many rejuvenators, even with vigorous shocking of the CRT neck?

I wonder if the metal is ferrous enough that a VERY Strong magnet could be used to pull the more flexible side of the break close enough for a weld function to work.