Brooks Instrument 5850E - Manual (Page 35)

4-3
Section 4 Maintenance &
Troubleshooting
Installation and Operation Manual
X-TMF-5850E-MFC-eng
Part Number: 541B102AAG
September, 2009
Brooks ® Model 5850E
Observe the output signal and, if necessary, perform the zero adjust-
ment procedure (Section 3-3). If the output signal will not zero properly,
refer to the sensor troubleshooting section and check the sensor. If the
sensor is electrically functional, the printed circuit board is defective and
will require replacement.
2. Connect the controller to a source of the gas on which it was originally
calibrated. Command 100% flow and adjust the inlet and outlet pres-
sures to the calibration conditions. Verify that the output signal reaches
and stabilizes at 5.000 Volts. Vary the command voltage over the 2 to
100% range and verify that the output signal follows the set-point.
Apply +15 Volts to the valve override input (refer to Figures 2-3 and 2-4
for terminal assignments) and verify that the output exceeds 5.000
Volts.
Apply -15 Volts to the valve override terminal and verify that the output
signal falls below 0.100 Volts. If possible, connect a flow measurement
device in series with the mass flow controller to observe the actual flow
behavior and verify the accuracy of the mass flow controller. If the mass
flow controller functions as described above, it is functioning properly
and the problem is most likely elsewhere. Table 4-1 lists possible
malfunctions which may be encountered during bench troubleshooting.
C. Sensor Troubleshooting
If it is believed the sensor coils are either open or shorted, troubleshoot
using Table 4-2. If any of the steps do not produce expected results, the
sensor assembly is defective and must be replaced. Refer to Section 4-4
for the disassembly and assembly procedures to use when replacing the
sensor.
Note: Do not attempt to disassemble the sensor.
D. Cleaning
Should the Model 5850E Mass Flow Controller require cleaning due to
deposition, use the following procedures:
1. Remove the unit from the system.
2. Refer to Section 4-4 to disassemble the controller.
3. Use a hemostat or tweezers to push a 0.007" dia. piano wire through
the flow sensor tube to remove any contamination. For best results
push the wire into downstream opening of the sensor tube (end closest
to the control valve). The sensor tube can be flushed with a non-
residuous solvent (Freon TF
TM recommended). A hypodermic needle
filled with solvent is a convenient means to accomplish this.