PS Magazine - TB 43-PS-664

PS, The Preventative Maintenance Monthly

ISSUE 664

MARCH 2008
PS Magazine - TB 43-PS-664 - Page 23 of 33
42
PS 664
MAR 08
Unfortunately, operators, some of
you aren’t happy with the sharpest
focus you can get. You’re sure you
can do a little better. So, you break
the seal on the locking ring and start
twisting the inFnity focus. Soon,
you’ve screwed the objective lens
so tight against the image intensiFer
tube that you crack the lens at worst
and reduce goggle performance at
best. Neither of these is a good thing!
Operators, your job concerning
the locking ring is to make sure it
isn’t loose or cracked like it says in
TM 11-5855-262-10-2. It is not your
job to loosen it. If the ring is loose
or cracked, turn it in to your NVG
maintainer for repairs.
Maintainers, your job is to reset the inFnity focus and lock the ring in place. To
ensure the locking ring stays in place, it is sealed with drops of sealing compound,
When the locking ring needs to be loosened, do it with cushioned slip-joint pliers,
NSN 5120-00-624-8065. This is all part of the instructions in Para 3-13 of TM 11-
5855-262-23&P-2.
T
he
diopter
adjustment
rings
on
eyepieces of the AN/AVS-6 series, AN/PVS-
7B or -7D and AN/PVS-14 let you focus your
NVD even if you normally wear glasses.
The rings adjust for the sharpest image
possible in a range of +2 to -6 diopters.
There’s a small pin to keep you from
overturning the ring.
But some of you want more!
You keep adjusting when there is no
place to adjust to. It’s not long until the
pin snaps and breaks. So here is the rule:
When the ring stops turning, you stop
turning the ring! It’s not going to get any
better, and it could get a lot worse!
When you do your Before/After PMCS
before you head out and when you
return, be careful. In some cases, pins are
breaking during the check!
AN/PVS-7B, -7D…
Infinity is
Far Enough
Is ring loose or cracked?
Don’t break seal
on
locking ring
Don’t Break
Diopter Pins!
to get the sharpest image on
an/pvs-
7
b or -
7
d night vision
goggles, the objective lens is
factory set at infinity.
this setting is held
by the objective lens
assembly locking ring.
during some mainte-
nance, the locking ring
is released, the objec-
tive lens is refocused
and the locking ring is
set and sealed again.
so far,
so good.
NVD Eyepieces…
664.42-43.indd
1-2
1/27/08
7:04:28 PM
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