My projector uses air-coupled (AC) tubes. How do I check to see if I have
a problem?
By inspecting your projector. Remove the lenses and look at the tube face. If you can see an air bubble
like this on all three tubes, then you are fine:
Unfortunately some tubes have larger black “borders” around them, and that
will prevent you from seeing the air bubble in a floor mounted or ceiling
mounted projector.
In that case you would have to take further steps as set out below.
Situation A:
You just got a “new” projector in. Luckily it is easy to find out if
there is still an air bubble in the coolant chamber.
- Remove the lenses
- Either remove the tube from the projector and hold it
upright, or
- Flip the whole projector onto its end carefully so
that the tubes face the ceiling.
- In either case a bubble of approx. ¼ to ½ inch in
diameter should be visible.
Should there be no bubble, then it is time to bleed the tube.
Situation B:
You bought a tube from someone else (this includes new tubes).
These tubes will most likely have been manufactured quite some time ago
and then sat on a shelf for an indefinite period of time. Because they did
not get any use, there was no way for the glycol to get heated enough for
the absorbed water to get desorbed again. Most tubes you will receive (be
they new or good used tubes) will have no air bubble left in them (due to
extended storage since production or last use). So, even those tubes will
need bleeding.
Here’s a picture of a new NEC PG red tube that has no bubble in it:
Situation C:
Your projector is floor mounted and you have been using it for some time
now, but never checked for the air bubble.
- You can either try to flip the projector on its rear
end after removing the lenses, or
- You have to remove the tubes from the projector.
Situation D:
Your projector is ceiling mounted and you have not checked for the air
bubble.
- You could try to remove the tubes from the projector
while it is ceiling mounted, though this is not recommended with most
projector models due to the complexity of the chassis construction. You
might be able to remove the tubes without too much trouble, but getting
it back in there will prove to be next to impossible. (The Sony G-series
seems to allow for tube removal and installs when ceiling mounted
though).
- So, you will unfortunately have to take the projector
down to inspect the tubes.
Yes, that’s a lot of work, but chances are that upon inspection you will
want to bleed the tubes anyhow, and in that case you would want the
projector down on the floor, as that makes working on it much easier as
pointed out above.
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