Xylem H-375 04101 WIND MONITOR-JR - Manual (Page 12)

Page 3
MAINTENANCE
Given proper care, the Wind Monitor should provide years of
service. The only components likely to need replacement due to
normal wear are the precision ball bearings and the wind
direction potentiometer. Only a qualified instrument technician
should perform the replacement. If service facilities are not
available, return the instrument to the company. Refer to the
drawings to become familiar with part names and locations. The
asterisk * which appears in the following outlines is a reminder
that maximum torque on all set screws is 80 oz-in.
POTENTIOMETER REPLACEMENT
The potentiometer has a life expectancy of fifty million revolu-
tions. As it becomes worn, the element may begin to produce
noisy signals or become nonlinear. When signal noise or non-
linearity becomes unacceptable, replace the potentiometer. Refer
to exploded view drawing and proceed as follows:
1. REMOVE MAIN HOUSING
a) Unscrew nose cone from main housing. Set o-ring aside
for later use.
b) Gently push main housing latch.
c ) While pushing latch, lift main housing up and remove it from
vertical shaft bearing rotor.
2. UNSOLDER TRANSDUCER WIRE
a) Remove junction box cover, exposing circuit board.
b) Remove screws holding circuit board.
c ) Unsolder three potentiometer wires (white, green, black),
two wind speed coil wires (red, black) and earth ground
wire (red) from board.
3. REMOVE POTENTIOMETER
a) Loosen set screw on potentiometer coupling and remove
it from potentiometer adjust thumbwheel.
b) Loosen set screw on potentiometer adjust thumbwheel
and remove it from potentiometer shaft extension.
c ) Loosen two set screws at base of transducer assembly
and remove assembly from vertical shaft.
d) Unscrew potentiometer housing from potentiometer
mounting & coil assembly.
e) Push potentiometer out of potentiometer mounting & coil
assembly by applying firm but gentle pressure on poten-
tiometer shaft extension. Set o-ring aside for later use.
f ) Loosen set screw on potentiometer shaft extension
and remove it from potentiometer shaft.
4. INSTALL NEW POTENTIOMETER
a) Place potentiometer shaft extension with o-ring on n e w
potentiometer (Gap 0.040") and tighten set screw*.
Regrease o-ring if necessary.
b) Push new potentiometer into potentiometer mounting & coil
assembly.
c ) Feed potentiometer and coil wires through hole in
bottom of potentiometer housing.
d) Screw potentiometer housing onto potentiometer
mounting & coil assembly.
e) Gently pull transducer wires through bottom of
potentiometer housing to take up any slack. Apply a
small amount of silicone sealant around hole.
f ) Install transducer assembly on vertical shaft allowing
0.5 mm (0.020") clearance from vertical bearing.
Tighten set screws* at bottom of transducer assembly.
g) Place potentiometer adjust thumbwheel on potentiometer
shaft extension and tighten set screw*.
h) Place potentiometer coupling on potentiometer
adjust thumbwheel. Do Not tighten set screw yet.
5. RECONNECT TRANSDUCER WIRES
a) Using needle-nose pliers or a paper clip bent to form a small
hook, gently pull transducer wires through hole in junction
box.
b) Solder wires to circuit board according to wiring diagram.
Observe color code.
c ) Secure circuit board in junction box using two screws
removed in step 2b. Do not overtighten.
6. REPLACE MAIN HOUSING
a) Place main housing over vertical shaft bearing rotor. Be
careful to align indexing key and channel in these two
assemblies.
b) Place main housing over vertical shaft bearing rotor until
potentiometer coupling is near top of main housing.
c ) Turn potentiometer adjust thumbwheel until potentiometer
coupling is oriented to engage ridge in top of main housing.
Set screw on potentiometer coupling should be facing the
front opening.
d) With potentiometer coupling properly oriented, continue
pushing main housing onto vertical shaft bearing rotor until
main housing latch locks into position with a “click”.
7. ALIGN VANE
a) Connect excitation voltage and signal conditioning elec-
tronics to terminal strip according to wiring diagram.
b) With mounting post held in position so junction box is facing
due south, orient vane to a known angular reference.
Details appear in CALIBRATION section.
c ) Reach in through front of main housing and turn potentiom-
eter adjust thumbwheel until signal conditioning system
indicates proper value.
d) Tighten set screw* on potentiometer coupling.
8. REPLACE NOSE CONE
a) Screw nose cone into main housing until o-ring seal is
seated. Be certain threads are properly engaged to avoid
cross-threading.
FLANGE BEARING REPLACEMENT
If anemometer bearings become noisy or wind speed threshold
increases above an acceptable level, bearings may need re-
placement. Check anemometer bearing condition using a Model
18310 Propeller Torque Disc. If needed, bearings are replaced
as follows.
1. REMOVE OLD BEARINGS
a) Unscrew nose cone. Set o-ring aside for later use.
b) Loosen set screw on magnet shaft collar and remove
magnet.
c ) Slide propeller shaft out of nose cone assembly.
d) Remove front bearing cap which covers front bearing.
e) Remove both front and rear bearings from nose cone
assembly. Insert edge of a pocket knife under bearing
flange and lift it out.
2. INSTALL NEW BEARINGS
a) Insert new front and rear bearings into nose cone.
b) Replace front bearing cap.
c ) Carefully slide propeller shaft thru bearings.
d) Place magnet on propeller shaft allowing 0.5 mm
(0.020") clearance from rear bearing.
e) Tighten set screw* on magnet shaft collar.
f ) Screw nose cone into main housing until o-ring seal
is seated. Be certain threads are properly engaged to
avoid cross-threading.
*Max set screw torque 80 oz-in