MKS MKSINST IE1000A, Instruction Manual

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Chapter Four: Maintenance and Troubleshooting Troubleshooting
37
Troubleshooting
Table 10: MFC Troubleshooting Chart
Symptoms Possible Cause Remedy
MFC does not respond to setpoint
and reports near zero flow
(valve current remains 0)
* MFC power has been turned off
* Incorrect cable used to connect MFC
* Cable has been damaged
* MFC has been given improper
analog setpoint signal
* MFC has been given VALVE
CLOSE override command
* Control circuit failure
* Verify the device is powered with the correct
input voltage at power supply
* Verify recommended cable configuration in
Chapter 3: Operation for interface type
* Verify cable continuity from end to end
* Verify setpoint signal range between pins
listed in Chapter 3: Operation for interface
type and check proper signal ground
* Verify valve override pin is not grounded to
POWER COMMON, CHASSIS GROUND,
or SIGNAL GROUND
* Return MFC for repair service per
instructions above
MFC does not respond to setpoint
and reports near zero flow
(valve current is max 260 mA)
* Upstream / downstream pneumatic
valves have not received adequate
actuation pressure
* Gas supply has not been started
* Clogged filter or process gas line
component upstream of MFC
* Clogged filter, sensor, orifice within
MFC
* Verify pneumatic air supply is not restricted
and provides minimum pressure specified by
valve manufacturer
* Verify gas pressure at supply regulator
exceeds minimum differential pressure
specified for MFC operating conditions
* Verify flow through components by
measuring pressure drop across each
restriction in the line with inert gas
* After verifying supply pressure upstream of
MFC, provide valve override command to
MFC and check for gas flow (independent
measurement) downstream of MFC.
If flow does not exist, then filter may be
clogged, orifice may be clogged, or valve
control circuit has failed.
If flow exists, then sensor may be clogged or
sensor circuit has failed
Return MFC for repair service per
instructions above