4200 Series Transmitters
Instruction Manual
Form 5596
November 2006
24
wiring board(s), or by replacing the pot/bushing
assembly (key 3, figures 12 and 14) depending on
which is defective.
3. Troubleshoot the transmitter circuit by measuring
the voltages.
4. Location of test voltage designated by V1
(table 8) is shown on the printed wiring board
assembly (figure 11).
5. Check the voltage at V1 as described in table 8.
6. If the voltage is 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 this voltage is 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 12 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 voltages V2 and V3 as described in
table 8:
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 V2 and V3 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 12) 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.
Transmitter Printed Wiring Board
Refer to figure 11 for component locations.
Removal:
1. Remove power from the transmitter.
2. With the transmitter compartment covers
removed, disconnect the connectors from J1, J2,
and J3 if they are used.
3. Note the locations of the wires, then disconnect
the wires from TB1.
4. Remove the three screws that hold the board in
place.
5. Grasp one of the components that protrudes from
the board, and gently lift the board from the
transmitter compartment.
6. Place the board on an anti-static surface for
repair or replacement.
