Instruction manual

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MODEL Xmt-P SECTION 10.0
TROUBLESHOOTING
10.2.2 Broken pH Glass and pH Glass Z High
These messages mean that the pH sensor glass impedance is outside the programmed limits. To read the impedance go
to the main display and press
ê
until Glass Imp appears in the display. The default lower limit is 10 MΩ. The default upper
limit is 1000 MΩ. Low glass impedance means the glass membrane — the sensing element in a pH sensor — is cracked
or broken. High glass impedance means the membrane is aging and nearing the end of its useful life. High impedance can
also mean the pH sensor is not completely submerged in the process liquid.
1. Check the sensor wiring, including connections in a junction box.
2. Verify that the sensor is completely submerged in the process liquid.
3. Verify that the software switch identifying the position of the preamplifier is properly set. See Section 7.4.
4. Check the sensor response in buffers. If the sensor can be calibrated, it is in satisfactory condition. To disable the fault
message, reprogram the glass impedance limits to include the measured impedance. If the sensor cannot be cali-
brated, it has failed and must be replaced.
10.2.3 ADC Read Error
The analog to digital converter has probably failed.
1. Verify that sensor wiring is correct and connections are tight. Be sure to check connections at the junction box if one
is being used. See Section 3.1 for wiring information.
2. Disconnect the sensor(s) and simulate temperature and sensor input. See Section 10.7 and 10.8.
3. If the transmitter does not respond to simulated signals, call the factory for assistance.
10.2.4 Ref Z Too High.
Ref Z Too High is an electrode fault message. Ref Z Too High means that the reference impedance exceeds the pro-
grammed Reference Fault Limit. A plugged or dry reference is the usual cause of a high reference impedance. High ref-
erence impedance also occurs if the sensor is not submerged in the process liquid or if inappropriate limits have been pro-
grammed into the transmitter.
The pH sensor is normally used with a high reference impedance. To disable the fault or warning diagnostic, program the
reference impedance to a high value.
10.2.5 EE Buffer Overflow
EE Buffer Overflow means the software is trying to change too many background variables at once. Remove power from
the transmitter for about 30 seconds. If the warning message does not disappear once power is restored, call the factory
for assistance.
10.2.6 EE Chksum Error
EE Chksum Error means a software setting changed when it was not supposed to. The EEPROM may be going bad. Call
the factory for assistance.
10.2.7 EE Write Error
EE Write Error usually means at least one byte in the EEPROM has gone bad. Try entering the data again. If the error
message continues to appear, call the factory for assistance.