CurtPalme.com Home Theater Forum

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Try to figure out how THIS happened!!!

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hmmm

That's a lot of bottom pin, a cylindrical screen at a big down angle perhaps.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Notice that the dark/light wear pattern is REVERSED? Worn phosphor is normally DARKER than unworn phosphor.

**AnalogRocks** · Posted: Fri May 27, 2016 6:58 am Post subject:

Looks like they used the outside to do a border. Instruments or HUD perhaps? Maybe Bogie's?

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I'll tell you later, after a few other people have decided to take a stab at it.

ecrabb · Posted: Fri May 27, 2016 6:25 pm Post subject:

The geometry is easy... Projector level with the top or bottom of a curved screen, like a wrap-around sim display or planetarium. Looks like it may have even been soft-edge-blended on the sides.

But, I don't understand why the wear pattern is reversed... That makes no sense. I like Analog's idea... Like this tube was making the "outside" image on a screen and blanked in the middle, while another projector was displaying a high-res image in the center. So, the bend might not be fitting on a concave display at all, but maybe matching the contour of a window/viewport, or HUD like Jeremy said.

Too many unknowns here to know for sure what this came out of unless you saw it yourself.

SC

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Incidentally, no, this is not a camera trick or photoshop or anything like that. This tube looks just like the picture
as seen in real life.

I'll reveal the answer tomorrow.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Guys

There is a phenomena called "bright burn", haven't seen it since the Novabeam days.

ecrabb · Posted: Fri May 27, 2016 7:33 pm Post subject:

ecrabb · Posted: Fri May 27, 2016 7:34 pm Post subject:

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I'm just going to tell you now. No sense in making you wait and bite your nails.

This tube is one I got recently and it didn't look like that when I got it.

It had the wrong pin base on it and I went to change out out, carefully so as not to break
the glass button and let all the vacuum leak out.

Well, that didn't go quite according to plan. Crack....hisssssss.....

And the interaction of the air with the aluminization and phosphor layer, coming into the tube slowly,
caused the wear pattern to become emphasized and reversed. For reasons that a chemist might better understand
than I can, the worn area basically did not change, while the UNWORN area exhibited a clearly visible darkening.

I've seen tubes that had been cracked with larger cracks, allowing air in faster, which show a bullseye pattern on the
phosphor face, too.

And I've seen tubes that had just flat out been snapped at the neck and the inrush of air just blew the whole phosphor layer clean off, too.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hey Steve

I never understood bright burn either, it was a small crosshair pattern in the center of a Novabeam green tube. I only saw that once.