Fisher 846 Instruction Manual page 19

NOTE:
AFTER FINAL CORRECTIVE ACTION, CHECK LOOP OPERATION.
IF NOT OK, RESTART TROUBLESHOOTING PROCEDURE.
1 REFER TO REPLACING THE MODULE FINAL ASSEMBLY
IN SECTION 6.
C0789/IL
voltmeter to confirm that proper input current is sup-
plied to the transducer.
8. Remove the terminal compartment cover (see
Warning above), and short the loop across the positive
(+) and the negative (–) terminals to check the output.
The output should be nearly 0 psi. If the output is not 0
psi, replace the module final assembly.
9. Remove the terminal compartment cover (see
Warning above), and, using a digital voltmeter, check
the voltage between the positive (+) and negative (–)
terminals of the Type 846. The voltage should mea-
sure 6.0 to 8.2 V. A lower voltage can indicate a short
Figure 5-5. Type 846 Field Troubleshooting Flowchart
in the input wires or defective controller. No voltage
can indicate an open circuit in the control loop. A volt-
age of greater than 8.5 volts indicates a problem with
the Type 846, a faulty or corroded connection at the
transducer, or an overcurrent condition. Replace the
module final assembly. If the voltage is still not in the
proper range (6.0 to 8.2 V), remove the terminal block
and terminal block connection board. Apply power to
the electrical feedthroughs. (Note the polarity of the
feed–throughs, shown in Figure 6-9.) Recheck the
voltage. If the voltage is in the proper range, replace
the terminal block and terminal block connection
Type 846
5–3