TM 5-6665-202-13
probes on 3 and 4 terminals of coils. The ap-
rotated, the resistor is defective and must be re-
placed. Test total resistance with a Whetstone
proximate resistance reading should be 2.6 to 2.8
ohms. If resistance readings are above or below
Bridge. Disconnect all connections on end termi-
2.6 to 2.8 ohms, transmitter coil could be defec-
nal of variable resistor (8) or slider terminal.
tive and detector head may have to be replaced.
Test resistor by connecting multimeter to slider
terminal and terminal of resistor marked CCW.
(2) Receiver coil. Test the receiver coil in
Rotate shaft and resistance should vary from 0
the detector head by placing the meter probes on
to 525 ohms. Connect multimeter to slider ter-
6 and 1 terminals of coils. Resistance should read
minal and terminal marked CW, again rotate
40 to 50 ohms. If resistance readings are above
shaft and resistance should vary from 0 to 525
or below 40 to 50 ohms, coils are defective and
ohms.
detector head should be replaoed.
d. Reassembly. Reassemble the short handle,
6-5. Short Handle, Detector Head, and
detector head, and balance coil in the reverse
Balance Coil
order of numerical sequence as illustrated in fig-
ure 6-6.
a. Disassembly. Disassemble the short handle,
detector head, and balanoe coil in the order of
numerical sequence as illustrated by figure 6-6.
6-6. Wiring
a. Cleaning.
NOTE
Observe location of electrical leads on balance
(1) Wipe the wires with a cloth dampened
coil and clearly tag them before disconnecting
slightly with an approved cleaning solvent and
to insure proper connection upon reassembly.
dry thoroughly.
b. Cleaning, Inspection, and Repair.
(2) Clean corrosion from terminals with a
(1) Wipe the detector head and short han-
brush or an approved corrosion remover.
dle with a clean cloth slightly dampened with
b. Inspection.
an approved cleaning solvent and dry thorough-
(1) Inspect the insulation for cracks, fray-
ly.
ing, and deterioration. Pay special attention to
(2) Wipe any accumulation of dirt or mois-
areas where wires pass through holes and over
ture from the balance coil with a clean, dry cloth.
rough or sharp edges. Wrap cracked or frayed
CAUTION
area with an approved electrical tape. Replace
Be careful of type of cleaning solvent
defective wires.
that is used on the equipment. The com-
(2) Inspect wire terminals for cracks, splits,
ponents are constructed of plastic and
corrosion, and insecure mounting. Replace a de-
will be damaged if they are cleaned with
fective terminal.
some types of solvent. Make sure a suit-
c. Testing. To test a wire for continuity, dis-
able solvent that is approved for plastic
connect one end of the wire from the compo-
is used when cleaning plastic compo-
nent to which it is attached. Touch the probes
nents.
of a multimeter, set on the lowest ohm scale, to
(3) Inspect the detector head for breaks,
each end of the wire. The multimeter should in-
cracks, damaged threaded areas, corroded elec-
dicate continuity. Replace a wire that does not
trical leads, or other defects.
show continuity.
(4) Inspect the balance coil for breaks,
d. Repair.
cracks, defective seals, corroded or broken elec-
(1) If a broken wire is accessible, remove
trical leads, or other damage,
sufficient insulation from each side of the break
(5) Inspect the handle for breaks, cracks,
to allow a good connection to the bared ends by
damaged threaded areas, or other defects.
twisting them together. Solder the connection
(6) Inspect the screws, bushings, washers,
and wrap it with electrical tape. Do not leave a
nut and adapter for chips, cracks, damaged
bare connection exposed.
threaded areas, or other defects.
CAUTION
(7) Replace a damaged or defective part as
Do not use acid-core solder when per-
necessary.
forming maintenance on the detector set.
c. Testing.
Acidic action can erode circuit compo-
(1) Transmitter coil. Test the transmitter
nents, resulting in a defective or inop-
coils in the detector head by placing the meter
