What is this?

[Eric H]

Looking at that mask the dots are arraigned in triangles like some of the splotches.

If the tabs snap on to glass posts I can see them getting broken, but then you should have stuff rattling around inside the tube.
I also wonder if it isn't sandwiched inside the two halves which would make it impossible to slid forward or back but perhaps not impossible to rotate, seems unlikely that would happen though.

If the guns were rotated exactly 120 degrees off then it should just have the colors mixed up (as happened with the French 15GP22)

[colorfixer]

Here's my $0.02:
-It could be possible that the mask deformed during the heating/evacuation cycle.
-If the tab(s) had detatched from the ring that surrounds the mask, there is likely not that much movement that would occur, and I concur that there would be something rattling around inside the envelope. Tapping the envelope would reveal microphonics. The mask looks really tough in any event.

-What about a damaged or misconfigured gun, with trajectories off or damage to the lens element structure?

[miniman82]

Tried the 'tipping trick' with no joy, also tried tapping the tube in different areas. Still the same result no matter what I do, which seems strange. I would have thought it would move at least a little, but it might just be jammed in there really well.

Here's pics, as promised.

First one is blank raster, brightness cranked up to see the splotches. Then I turned on the guns one at a time: first blue, then green, then red. Red is the most telling of course, you can clearly see the edge of the shadow mask off to the left.

5th photo is actually an animated GIF, so you can see the progression.

[miniman82]

Originally Posted by Eric H

Looking at that mask the dots are arraigned in triangles like some of the splotches.

It does make sense that if the mask did come loose and pull back from the screen, the beams would be larger once they actually reached the phosphor...

If the tabs snap on to glass posts I can see them getting broken, but then you should have stuff rattling around inside the tube.

Good idea, I'm not as averse to shaking the tube as I am to tapping it.


colorfixer: I find it highly unlikely that the mask would deform in the oven, remember they have to bake these things when they're new as well. That and the fact the Scotty claims a very good track record on all glass tubes, according to him the onyl troubles are with metal/glass ones. I.E. 21AXP, 15G, ect. I don't think there's anything wrong with the gun either, since all the screen/grid controls work like they should.

[DaveWM]

did you say its the same with just a blank raster?