Vaisala WAA151 - Manual (Page 19)

Chapter 4 ________________________________________________ Maintenance
VAISALA__________________________________________________________17
10. Remove the internal retaining ring at the bottom of the
shaft (using narrow-pointed pliers).
11. Remove the lower bearing.
12. Push out the shaft downwards through the upper body.
13. Remove the top bearing after pulling out the shaft.
To reassemble the sensor, reverse the above work order .
The numbers in parenthesis refer to Figure 6 on page 19.
1. Take the previous steps in opposite order until
assembling the chopper disc.
NOTE Be careful when handling the new ball bearings. Do not
drop them or force them onto the shaft.
2. Attach the chopper disc (7) back onto the shaft. The
disc has to be positioned so that the disc teeth do not
touch the opto-coupler (6) on the circuit board. Tighten
the screw.
CAUTION Assure that the chopper disc teeth do not touch the opto-
coupler. There should be 1 to 2 mm space between the
bottom of the opto-coupler and the disc teeth.
3. Attach the heating element outlet (5) to the circuit
board. Put the circuit board in place and fasten it with
spacers (5).
4. Put the lower body assembly (4) carefully into place.
Fasten the three screws (3) at the bottom of the sensor.
Make sure that the bigger O-ring (14) is correctly
positioned between the upper and the lower sensor
bodies. The O-ring is recommended to be replaced
with a new one after each opening. Check also that the
connector's O-ring (14) is properly in its place.