Is it normal to have a tube that is not completely covered in the corners?

[ebo0763]

I have a WG k7400 and the phosphor and mask don't completely cover the bottom right and top left corner. It's not bad caps or setting problem, the tube is just this way. It's as if the inside of the tube (where the mask is) start curving but is not hidden by the black border.

Do you encounter that often? I'm pretty picky on this and I'm wondering if it's like that most of the time.

Here's kind of what it looks like. The light blue area represents the part where the mask and phosphor folds back inwards.

[MonMotha]

That seems...unusual to me.  If it's just the imaged area, you just need to rotate the image slightly (i.e. turn the yoke), or live with a little more overscan.  I don't think any of my tubes I've ever seen don't have phosphor/mask extending all the way to the border area of the tube face.  What's the make of the tube on this thing?

[ebo0763]

Interesting. So it's the first time you that? Ho well...

And the yoke adjustment will only change where the electron beam hits on the inside of the tube. It's not going to change the shape of the inside of the tube, so I'll leave it as it is.

And the model is a Zenith - EIA-1101 -25".

[boardjunkie]

Shape of the inside of the tube?? Meh....all you need to do is twist the yoke in the right direction that corrects the cocked pix.

[Rickn]

I may have missed it but is the picture itself tilted??

I have seen something like this before.... it was caused by a slght maufacturing error and match of the tube to the yoke. In that case if the yoke was slightly too far back on the neck, then the electron beam when deflected would hit the inside of the neck at the outer corners. Typically just the blue beam.
2 attempts or possibility to fix it:
move the yoke slightly forward or add magnets in the corners affected.

[boardjunkie]

Magnets will screw with color purity....I don't recommend that. Move the yoke first.

[Rickn]

Yes, he is right magnets may screw up the purity, but it is the easiest fix, if it does not work remove the magnets.

I have been doing this for 30 years and if the monitor was here we would have the problem fixed in like 5 minutes.