PS Magazine - TB 43-PS-589

PS, The Preventative Maintenance Monthly

ISSUE 589

DECEMBER 2001
PS Magazine - TB 43-PS-589 - Page 24 of 32
If you replace the power cable,
carefully trace the markings to iden-
tify the positive line (with fuse) and
the ground line. And if you get a
flush connector tip, it’s a good idea
to put a flap of tape over the tip
when you remove the PLGR to
avoid metal-to-metal contact.
The vibration problem can be addressed by ordering a cable with a locking knurled
nut, NSN 6150-01-469-6066 to make a positive connection that stays connected.
One complication with the knurled nut solution is that if you are also using the
SINCGARS ground plate there isn’t quite enough thread left for the nut to grip. In
that case use some self-adhesive hook-and-pile tape to keep the plug in place.
Just run a strip of 1-in hook-and-pile tape, NSN 8315-01-445-8812, from the pri-
mary battery cap to the start of the handle right beside the J2/J3/J4 connector covers.
PS 589
DEC 01
44
PS 589
DEC 01
45
PLGR…
U
sing the external power cable NSN 6150-01-375-8661, is a great way to tap
vehicle power and avoid the use of batteries to operate your AN/PSN-11 precision
lightweight GPS receiver (PLGR). But you need to know a couple of things about
this cable.
The power cable has an in-line fuse that is designed to blow when something
shorts the power circuit. The fuse can only blow one time to protect your PLGR.
You need to replace it right away but you also need to answer the question: “Why
did the line short and the fuse blow in the first place?”
The electrical short usually results from metal-to-metal contact of the center
conductor when the cable is loose, not attached to the PLGR or when a cable slips
out of place due to heavy vibration. In ether case, metal-to-metal contact of the
center conductor shorts the line and blows the fuse.
Start by checking out your external power cable. There have been some slight
design variations since the PLGR external power cable was first introduced in
1993. Even though all the cables in field use have
the same NSN, they are not exactly alike. On
some cables the center conductor (the positive
wire) is flush instead of being recessed like the
original. This makes it easy for the center con-
ductor to make metal-to-metal contact when not
connected to the PLGR. Since the power cable is
still “hot”, when it makes metal-to-metal contact,
the fuse will blow. Without corrective action, the
short may eventually melt the power cable!
Get the
improved
cable
Vibration
a problem?
Order
locking nut
cable
Use hook and pile…
…to hold the cable…
…in place
What
happened
to you?
I was
shorted
out!
that
would
burn me
up, too!
The good news is that
requests for this cable, NSN
now
be
filled with an
improved
version that has a recessed
positive conductor and better
ground markings!
When you connect the power cable, fasten is down with the hook and pile. You can
also try putting a piece of high-density foam or other non-metallic material between
the PLGR mount and the back of the PLGR to firmly hold connectors in place.
589. 44-45 (C)
10/20/01
4:16 PM
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