PS Magazine - TB 43-PS-619
PS, The Preventative Maintenance Monthly
ISSUE 619
JUNE 2004
PS 619
JUN 04
45
KEEp sHOp VOLTAGE UNDER CONTROL
Dear Editor,
C & E shops need to make sure the source of DC voltage in their shop
is correctly grounded. Many of them aren’t.
If you’re working on commo equipment and have noticed sparks between
your work bench or other grounded objects or have been “bitten” by elec-
tricity, you need to check the ground on the central station power supply
that provides 28 DC volts.
Many of these supplies are capa-
ble of producing 200 or more
amperes of current. That’s enough to
cause serious injury!
Almost all these power supplies
have two output terminals
-positive
and negative.
Neither of these
terminals are connected to
the power supply’s chassis!
Here’s what you need to do:
Connect the negative terminal of the
power supply to the station ground
buss with a cable of sufficient size
to handle the entire output capacity
of the power supply.
Now check the voltage between
the positive terminal to the ground.
If you get 28 DC volts, you’re okay.
Don’t be fooled by a “no voltage
reading” on your meter when you
check for voltage between the
ground and the negative side of the
power source. Verify the connection
both visually and with a continuity
check with an ohm meter.
Edward Butorajac
Ft Gordon, GA
A little
drop
here…
…and
here
will do
the
job
AB-1339/G Antenna…
what the
heck happened
to
you?
I got
‘bit’ by
elec-
tricity.
see!
sheesh! you
really
need to check the
ground on the Central
station power supply!
looks
like they
need
something
from me.
I
know
that
look. it
says…
Shop power supplies are often
installed by folks who are not aware
of the need to have the chassis and
the negative terminal of the voltage
source bonded together and connect-
ed to the station ground for proper
grounding. This could lead to a shock
hazard, arcing of the chassis to the
work bench or other grounded item,
or RF burns. Take Ed’s advice and
check out your shop’s power supply
for the right grounds. Also, check the
power supply TM or manufacturer to
make sure that the power supply is
installed properly and that tying the
secondary to ground is okay.
From the desk
of the
Editor
AN/PVS-14 NVD LIF Advice
If you overtighten the light interference filter (LIF), NSN 5855- 01-379-1410, you
can crack the objective lens on your AN/PVS-14 night vision device. Even
though you’re given a wrench to use, the LIF should be tightened only hand
tight. When the filter is in place and secure, stop tightening. Use the wrench to
remove
an overtightened LIF.
T
hat’s what the A5 and A7 cables on your
AB-1339/G antenna mast would ask you,
if they could talk.
Those cables run through your mast and
extend your antenna. That makes them
pretty important fellas. But some of you
are letting those fellas gather a lot of rust.
So, when you’re raising the antenna, put
a couple of drops of OE-10 on the cables.
And, eyeball the cables whenever you han-
dle the mast. If you see rust start to bloom,
well, doing a little oiling won’t kill ya!
…WOULD
A LITTLE OIL
KILL YA?
619. 44-45 (C)
4/29/04
5:51 PM
Page 1
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