Peristaltic Pump Motor Replacement
The pump motor is linked internally to the peristaltic pump via a brass coupling with a slot in the end.
The slot matches up with a drive pin that runs perpendicularly through the pump shaft. The brass
coupling is machined such that the connection between the pump and the motor will not cause binding
that could prematurely wear the motor gearbox.
If the brass coupling is mounted on the shaft too close to the motor gearbox, it could bind on the back
of the pump head, or the drive pin could bind on the bottom of the brass coupling end slot.
The pump motor is now only available with the brass coupling pre-installed (except drop-shipped
motors), as an assembly, to ensure the clearances necessary to avoid motor and pump binding.
Should the coupling ever be removed from the motor, it should be reinstalled with exactly a 1/16” gap
between the motor gear box bearing and the back of the brass coupling. The brass coupling should
also be oriented so that the set-screw will be tightened against the center of the flat spot on the motor
shaft.
1. Turn off the AC power to the FX-1000p.
2. Remove the inner cover plate to access the motor and PC boards.
3 Disconnect the motor wiring at the lower power supply board (TB-1B). Note the wiring color and
placement in the terminal strip.
4. Remove the two extended brass nuts that hold the motor to the PVC mounting block.
5. Remove the old motor with ground wire and brass coupling assembly.
6. Place the new pump motor onto the threaded studs in the pump motor mounting block. Place the
ring terminal of the green ground wire onto one of the studs, generally the right hand stud toward
the back of the analyzer. Fasten the motor and ground wire by hand with the (2) extended brass
nuts (
Figure 46
); it should be snug, but do not completely tighten yet.
7. To check the coupling and pump alignment, rotate the pump using a slotted screwdriver to
turn the screw in the face of the pump. The pump will be somewhat difficult to turn because of
the gear reduction in the motor gearbox. If the coupling slot and drive pin in the pump weren’t
aligned, you may hear a “click” and feel the pump move in as they align and engage. Make sure
the pump turns freely and smoothly, with no binding or stiffness.
8. If the pump head rotation is good, reinstall the tubing, and place the analyzer back into operation.
Tighten extended brass nuts.
The pump head should rotate smoothly and continuously at 4 revolutions per minute. If it does not,
or the motor sounds like it is “skipping”, or the pump head is stopped easily with finger pressure, the
motor is binding and may wear out prematurely.
Maintenance
38
FX-1000p
