Tube Condition (Wear)
Let’s look at some tube wear pictures. It’s completely normal for tubes to
show some wear from as low as 500 to 4000 hours. Much like carbon build-up in a
car engine, a bit of tube wear will not greatly affect the performance of the
CRT projector. The below tube shows light even wear across the phosphor. This
tube has been correctly used. There’s a minimum of virgin phosphor area on this tube,
the wear is light and even, and setting up a new image within the wear area is
easy to do. You will get 8500 hours + use out of this tube.
Now, let’s look at a tube that can still be useable, but is not in as good a
shape as the above image.
This tube has a dark line worn into the extreme bottom of the tube. This isn’t
really an issue, as you can shift the image into the less worn area of the tube
with the raster shift function. The raster on the original installation of this
tube is shifted slightly to the right of the tube face, but again, as long as
you fit the image within the wear area, you can get an acceptable picture from
this tube. The worst aspects of this tube is that the raster is not quite evenly
worn from the top of the bottom of the tube. This will show itself as slight
shading in the image, and an all white screen will show slight uneven tint over
the screen area. The other thing to consider is that the tube shows light text
wear. It looks like this tube projected static graphs or similar images for long
periods of time. If this tube is the blue one, you’ll get slight yellowing of an
all white field in these darker wear areas.
Below is a picture of a tube that is nearing the end of it’s life. This tube
has maybe 7000 hours of use on it, has uneven wear from top to bottom, and has
some text type wear on the face of the tube as well. As the saying goes, “You
might use this tube, I wouldn’t”. :)
This tube is good for non-critical viewing or to get a set running that has
even heavier wear or for video gaming use where some wear isn’t a big issue.
This last tube wear picture will produce a minimal image useable for home
theater use. It shows that this tube might have been used in two previous
installations. There is some large and light 4:3 wear area, but there is also a
smaller and heavier wear area within this larger area, suggesting that the
projector got moved at some point in time and a smaller phosphor area was used
the second time around. To add to this uneven wear, there is some distinct text
wear on the face of this tube. This will make for very uneven light projection
from this tube.
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