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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.