Table 5.1 continued...
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Symptoms and Clues Possible Cause Try This
4 SYSTEM DOES NOT CONTROL
AT COMMANDED SET POINT
CLUE: The PCS 400 requires an
input pressure higher than the
control output set point, or
pneumatics section is working
improperly.
The source pressure is not
high enough.
----------------------
The cable connecting the
electrical module to the
regulator is disconnected.
----------------------
The solenoid valves are not
opening to let pressure into or
out of the control module.
----------------------
PCS 400 has a pneumatic
leak.
Apply source pressure 10 psi (or
10%) greater than the commanded
set point.
--------------------------
Check the 9 pin connector
Å on
the electrical module and the pcb
connector
à on top of the
regulator. Make sure the regulator
connector is not shorted against
something.
--------------------------
Run the solenoid valve test to verify
that all of the valves are working.
CAUTION: HIGH PRESSURES
COULD BE PRESENT AT THE
GAUGE OUTPUT DURING THE
TEST!
--------------------------
See next section.
5
SYSTEM HAS A PNEUMATIC
LEAK
CLUE: Possible sources for leaks
are solenoids, plumbing, or relief
valves.
Because of the extreme
resolution of the PCS 400,
very small temperature
changes on trapped volumes
of gas will appear as changes
in pressure. The PCS 400 will
control small leaks with no
effect on any control
parameters. The built-in leak
diagnostics are designed to
help troubleshoot problems
but not return absolute
numbers.
Run internal leak test and system
leak test to determine if leak is
inside unit or external. Most internal
leaks appear at solenoid valves,
relief valves and fittings.
6 SYSTEM DOES NOT RESPOND
FROM THE FRONT PANEL
KEYPAD
CLUE: Signals are not being
transferred from the front panel
keypad to the electrical module.
The keypad cable is
disconnected at the front
panel
È or at the electrical
module.
Re-connect the cable.
MAINTENANCE PCS 400
5-4 www.mensor.com
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