Yokogawa DO402 Dissolved Oxygen Analyzer - Manual (Page 79)

IM 12J05D02-01E
Troubleshooting 8-1
8. TROUBLESHOOTING
This chapter describes the countermeasures for failures, classifying the cases into three categories:
dissolvedoxygen converter failure, detection of failure with the self-diagnosis function, and abnormal
measured values. The causes for abnormal measured values are not limited to equipment failures. if an
abnormal phenomenon occurs, first check the following items:
• Is the property of the measuring solution different from normal ?
• Is the dissolvedoxygen sensor properly installed?
8-1. Measures in the case of converter operation failure
8-1-1. No dissolved-oxygen converter operation
If the converter does not operate even when the power is supplied, one cause may be a blown fuse
inside the converter.
Examine the fuse by turning off the power supply (see Subsection 3-3-1 on page 3-5).
If the fuse is blown, replace it with a new one. If fuses frequently blow and the cause is not clear, request
an inspection by Yokogawa.
If the fuse is normal, examine the wiring system.
8-1-2. Operation key or display failure
If the operation keys do not operate smoothly or the display fails (e.g., a missing character segment),
repair of the printed circuit board (digital board) (replacement with a new one) is required.
After the printed circuit board is replaced, operation checks and parameter settings are necessary.
Contact Yokogawa and request board-replacement work.