Tech Note: Unreleased
Date: October 22, 2013
may become damaged. Once the cell is removed, the nut (8) which holds the
heater in place becomes visible.
Heater Strut Removal
Open the terminal cover on the head of the probe by loosening the set screw
using an allen wrench and then turn the cover counter-clockwise. Remove the
positive cell wire and both thermocouple wires from the top terminal block (26)
using a Philips-head screwdriver to loosen the screws (31). The top terminal block
can now be removed by loosening the screws (28) in the upper-left and lower-
right corners, being careful not to lose the spacers (29) between the screws and
terminal block. The two heater wires may now be removed using the Philips-
head screwdriver. Next, loosen the two screws (15) that hold the bolt cover (12)
to the air connector block (13) and slide the cover back toward the flange. This
will expose the four sets of bolts (10) and washers (11) which hold the terminal
box to the air connector and probe. Remove (10) by turning them counter-
clockwise, taking care not to let the terminal box (16) fall. Gently slide the
terminal box away from the probe without damaging the wiring. Loosen screw
(19) to detach the air connector (13) from the heater strut (23). Flip the probe
over and using special service tool M1234HD-A, insert the tool’s raised end into
the notches in the nut (8). Remove the nut by sticking a tool such as a
screwdriver in the hole at the other end of the service tool and turn it counter-
clockwise. Once the nut is removed the heat strut (23) can be removed from
the probe’s tube (24). The heater strut should be removed with care to not
damage the calibration line. Remove the contactor spring (9), which is located
in the groove near the back of where the heater nut was, with a pick or pair of
tweezers. Now is a good time to label wiring if it is deemed necessary.
Air Connector Servicing
Remove the translucent o-ring (14) from the air connector and discard it. Loosen
the screw (25) holding the plate (17) to the air connector (13) by turning it
counter-clockwise. Once the plate is removed the air caps (20) can be
removed. Use a pick to remove o-ring (21) from the reference and calibration
air caps (20). The other o-rings (22) are in the connector holes that the air caps
were in. These can also be removed with a pick or by pushing them out from the
back. Discard all old o-rings. Install an o-ring (22) in the groove in each air cap
hole, ensuring it is seated at the bottom of the hole. Then install an o-ring (21) on