Yokogawa PH72 Personal pH/ORP Meter - Manual (Page 60)

IM 12B03D02-01E
7-3
7. Troubleshooting
(2) Err2 Abnormal asymmetry potential
Appears during calibration.
A sensor deteriorates in service and the emf deviates from the initial one. If the
difference increases and exceeds the limit that can be compensated by calibration, an
Err2 message will appear. It will also appear if the pH value of the standard solution is
abnormal or if the asymmetry potential is outside the range of -96 to 120 mV.
Possible Causes:
• Clogged liquid junction.
• Insulation failure in electronics.
• Improper standard solution.
• Dirt or deposits on electrode.
• Electrode filling solution has been depleted.
• Expired battery life.
• Electrode contaminated with standard solution.
Corrective Actions:
• Remove dirt or deposits from the liquid junction. (See Section 6.2.)
• Remove stain or moisture from the connectors. (See Section 6.6.)
• Use properly prepared standard solutions. (See Chapter 4)
• Perform acid cleaning. (See Section 6.2.)
• For KCl refillable type sensors, replenish with filling solution. (See Section 6.5.)
• Replace the sensor. (See Section 1.6.)
• For KCl refillable type sensors, replace the filling solution.