Type 546, 546S, and 546NS
10
3. Check the resistance of the transducer circuit to
see that it coincides with the value listed on the circuit
identification tag located on the torque motor.
4. Check the terminal lugs for proper connections. If
reverse action of the transducer is observed, simply
reverse the input leads as indicated in the Reversing
the Action procedures in the Operating Information
section.
Pneumatic
CAUTION
Do not attempt to remove the nozzle
(key 19, figure 9) for any reason. Nozzle
removal requires disassembling the
torque motor. Disassembling the torque
motor will permanently reduce the
strength of the magnets, causing im-
proper operation. Also, do not adjust
the baffle (key 18, figure 9). The spacing
between the baffle and nozzle is preset
and locked at the factory to obtain opti-
mum performance of the transducer.
1. Connect supply pressure and a pressure gauge to
monitor the output. Check the operation of the trans-
ducer as follows:
a. Force the baffle (key 18, figure 9) against the
nozzle. The output pressure should build up to
approximately the supply pressure. If it does not,
check for a leak in the pneumatic system or a burr
on the nozzle.
b. Force the baffle away from the nozzle. The out-
put pressure should drop to less than 1 psig (0.07
bar). If it does not, check the flame arrestors in the
transducer case (see figure 8). If the flame arres-
tors require cleaning, first remove the torque motor
assembly from the case by removing four machine
screws (key 9, figure 8). Then, clean the flame ar-
restors by blowing them out with air pressure.
2. Check zero and span adjustment for proper setting.
Refer to the adjustments procedure.
3. Check the supply pressure. It should be at least 5
psig (0.3 bar) above the upper limit of the output pres-
sure range.
4. Check the filter regulator for moisture in the drip-
well. Drain off any moisture, and clean the filter ele-
ment if necessary.
5. If the transducer cycles, be sure there are no sharp
bends in the copper capillary feedback tubing (key 56,
figure 9) and that the tubing is not plugged.
6. Check the nozzle. If it is clogged, remove the entire
torque motor assembly from the case by removing
four machine screws (key 9, figure 8). Run a wire
through the nozzle from the underside of the assem-
bly.
7. Erratic operation may be caused by metal chips in
the air gap between the armature and the pole pieces.
Blow any chips out of the torque motor assembly with
low pressure air.
8. If a problem persists, check the relay as described
in the Type 82 Relay Maintenance procedures in this
section.
Alignment
The following alignment procedures can be used in
conjunction with troubleshooting procedures to correct
the operation of a faulty transducer.
Span Adjustment
Refer to figure 9 for key number locations, unless
otherwise directed.
If setting the required span is not possible, additional
span adjustment can be obtained by shifting the entire
span adjustment assembly (key 55) at the flexure pivot
end. The alignment procedure is as follows:
1. Shut off the dc input signal and supply pressure to
the transducer.
2. Disconnect the external lead wires from the termi-
nal mounting bracket assembly (key 53).
3. Loosen the four machine screws (key 9, figure 8)
that hold the torque motor assembly to the case. Re-
move the entire torque motor assembly from the case.
4. Loosen the two flexure pivot screws (key 25) that
hold the flexure pivot to the torque motor assembly
base.
5. Slide the span adjustment assembly in or out as
required. Sliding it in toward the base decreases the
span; sliding it out away from the base increases the
span.
6. Tighten the flexure pivot screws. Replace the
torque motor assembly, and tighten the screws (key 9,
figure 8). Make sure that the O-ring (key 37) is in
place. Connect the external lead wires, and turn on the
air supply.
7. Make final adjustment of the span with the span
adjustment screw.
