CTC-4 Director 21

[miniman82]

Shouldn't be possible, the shadow mask is spot welded to a frame which has a lip on it that extends back towards the electron gun specifically to prevent stray electrons.

[Phil Nelson]

One last question: does the display on the screen face change in any way when the orange glow is dancing? I don't have a theory about what it is -- just curious.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[SwizzyMan]

Originally Posted by Phil Nelson

One last question: does the display on the screen face change in any way when the orange glow is dancing? I don't have a theory about what it is -- just curious.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

I can't say the picture changes at all. Absolutely nothing out the ordinary with the screen brightness.

[jr_tech]

Originally Posted by miniman82

Shouldn't be possible, the shadow mask is spot welded to a frame which has a lip on it that extends back towards the electron gun specifically to prevent stray electrons.

Interesting, I haver broken open a 21FBP22 so have not seen this lip... how far back does it go... far enough to cover the frit bead? Perhaps the frit bead is aluminized or dagged over to prevent charging and or secondary emission, or the lip perhaps covers it ?

just curious,

jr

[miniman82]

Originally Posted by jr_tech

Interesting, I haver broken open a 21FBP22 so have not seen this lip... how far back does it go... far enough to cover the frit bead? Perhaps the frit bead is aluminized or dagged over to prevent charging and or secondary emission, or the lip perhaps covers it?

Been a while since I have looked at it, but on a guess probably 3/4" or a full 1"? Something like that. This particular mask and frame assembly was from an AXP that got turned into a picture frame, but I don't think they changed anything about its construction in later tubes. Don't remember where I read about it either, but I know that the lip in there is to prevent stray electrons from reaching the screen and lighting up any of the phosphor dots.

[SwizzyMan]

Here's a video of what it looked like back in December of 2015. I guess alignment can go that far off after sitting dormant for 8 months? https://www.youtube.com/watch?v=O15e4R8jr8k

[DaveWM]

alignment does not go off as far as the coils are concerned unless there has been screw driver drift. I would look somewhere else. Clearly the beat pattern is prob from miss tuning of the fine tune adjustment. the other is some kind of interference.

I assume you are using some kind of RF devise for the signal, is that the same as the early example? If RF try a different channel if that is an option. Assuming you have matching transformers and good quality cable for feeding the signal.

[SwizzyMan]

Originally Posted by DaveWM

alignment does not go off as far as the coils are concerned unless there has been screw driver drift. I would look somewhere else. Clearly the beat pattern is prob from miss tuning of the fine tune adjustment. the other is some kind of interference.

I assume you are using some kind of RF devise for the signal, is that the same as the early example? If RF try a different channel if that is an option. Assuming you have matching transformers and good quality cable for feeding the signal.

I'm using a BT modulator. It has that horrible hum when the modulation is too high, but my other two roundies don't have the overmodulation hum in their speakers and for some reason only the 4 is humming. The fine tuning knob only turns about an eighth of a turn before I lose sync. It was originally hooked up to a dtv converter box.