|
It does indeed happen with brand new ASC brand .0047 uF 6000 V tubular capacitors.
If you probe the plates of the vertical and horizontal outputs (which I have many times), you don't see anything until the problem is extremely severe -- then you can see the slightest wiggle on the plates of the vertical output. No where near enough to explain the effect. The keystone waveform is slightly visible on the horizontal output plates. But surpsingly, when I add a huge filter cap (more than 10 uF) on the 800 V line feeding the horizontal, the the waveform cleans up, but the keystone on the CRT is still there.
The main effect has to be occurring beyond the capacitor at the CRT deflection plates, where you cannot easily probe. I may try what you suggested to make a probe using another HV cap. However, the behavior in that cap might be similar and obscure the effect. I won't bother to change this particular set back to the bad caps, but I have another one (Sentinel 400 TV) with the same problem that I will try within the next few days and see if I can learn more about what is happening.
|