66
MODEL 54e pH/ORP
SECTION 8.0
TROUBLESHOOTING
TABLE 8-3. Troubleshooting Guide (continued)
Table 8-3 is continued on the following page
PROBLEM OR CONDITION
PROBABLE CAUSE AND
FOR MORE HELP,
CORRECTIVE ACTION
REFER TO
Controller "short spans."
Coated glass electrode -
Buffer check with 2-point
Clean with soft cloth
calibration gives slope less
and clean water.
than 47 mV/pH .
"lo slope error"
Service 381+ Reference Junction
and Solution.
Old glass electrode -
If used for more than 1 yr, replace
electrode.
Change in pH slope (value
Old or coated glass electrode -
shrinking) after 2-point calibration.
Clean or replace glass electrode.
Bad RTD value -
Temp.Comp. Troubleshooting
See Temp. Comp. Troubleshooting
Procedure, Section 8.2
Procedure with expected RTD value
resistances at temperature values.
pH value locks up
Glass electrode cracked -
(no change in buffers).
Replace glass electrode.
Coated glass electrode -
Clean glass electrode.
Displayed pH value not the same
Grab sample incorrect -
Calibration, Section 4.0
as grab sample of process.
Reevaluate sample technique and
equipment.
Unclear which is correct -
Calibration, Section 4.0
Retest with new buffer solution.
Controller out of calibration -
Calibration, Section 4.0
Recalibrate per Calibration,
(See Section 3.0)
Display reads off scale.
(381+ Sensor) Reference depleted -
Replace reference electrolyte as
instructed in 381+ manual.
Defective preamplifier -
Section 8.0
Check preamplifier as instructed in
Preamp Troubleshooting Procedure, and
replace preamplifier, if defective.
Electrode not in process solution -
Wiring, Section 3.0
Make sure sensor is in solution.
Open circuit within glass electrode -
Replace glass electrode.
(381+ Sensor) Plugged reference -
Replace reference junction.
Recharge reference solution.
