4200 Series Transmitters
Instruction Manual
Form 5596
July 2005
23
Troubleshooting Procedures
Transmitter Circuit
Note
On transmitters with position
switches, the (R) terminal on the field
circuit printed wiring board must be
connected to the power supply
negative (−) terminal for proper
transmitter operation, even though the
position switch outputs are not used.
1. Verify that the instrument is receiving power, and
verify that the receiving device(s) are operating
correctly.
2. If the transmitter is the problem, maintenance can
be performed by either sending the entire instrument
to the factory for repair, by replacing the printed
wiring board(s), or by replacing the pot/bushing
assembly (key 3, figures 13 and 14) depending on
which is defective.
3. Troubleshoot the transmitter circuit by measuring
the voltages.
4. Locations of test voltages designated by V1 and
V2 (table 7) are shown on the printed wiring board
assembly (figure 11).
5. Check the voltages V1 and V2 as described in
table 7.
6. If either or both of the voltages are not present,
field repair of the instrument is not recommended.
Either replace the printed wiring board or return the
instrument to the factory for repair.
7. If these voltages are present, the potentiometer
may be the source of trouble.
8. Check the voltage between TP3 (+) and TP4 (−)
as the position of the potentiometer is varied. For
Type 4212 and 4222 transmitters, check the voltage
between TP5 and TP6 as the position of the
potentiometer is varied.
a. If the voltage does not vary with position,
perform the potentiometer alignment. If the
problem remains, replace the pot/bushing
assembly (key 3, figure 13 or 14).
b. If the potentiometer wiper voltage checks
good, but the transmitter output is constant or
non-linear, the problem may be due to improper
potentiometer alignment. Perform the
potentiometer alignment procedures; then repeat
step 8 above.
c. If the potentiometer voltage is present but the
transmitter output current does not change
linearly as the position of the potentiometer
changes, replace the transmitter printed wiring
board, or return the transmitter to the factory for
repair.
Position Switch Circuit
1. Ensure that the position switch circuit is
connected correctly, and that the terminal marked
(R) on the field circuit printed wiring board is
returned to the negative terminal of the supply. Refer
to figure 4 for wiring connections.
2. Ensure that the power supply voltage is between
20 and 30 volts dc.
3. Check the voltages V3 and V4 as described in
table 7:
a. If either or both of the voltages are not
present, field repair of the instrument is not
recommended. Return the instrument to the
factory for repair.
b. If V3 and V4 are correct, continue with the
following steps:
4. Perform the high and low position switch
calibration procedures in the Calibration section.
5. If the position switches cannot be set, replace the
field circuit printed wiring board (figure 13) or return
the instrument to the factory for repair.
Printed Wiring Board Removal and
Replacement
WARNING
Refer to the Maintenance WARNING at
the beginning of this section.
CAUTION
Electrostatic voltages present in the
environment may be transferred to the
transmitter printed wiring board which
may cause failure or degraded
performance. Use appropriate
antistatic procedures when working
with the printed wiring board to protect
the electronic circuits.
