8
Diagnostics and corrective maintenance
Diagnosis
Diagnosis refers to the identification of instrument malfunctions and defects.
Corrective maintenance:
• replacement of parts diagnosed to be defective;
• testing of instrument and measuring system function;
• restoration of complete functionality.
Diagnosis based on the error table below and depending on difficulty and measuring
equipment at hand is to be performed by:
• trained operator personnel
• operator’s electricians
• company responsible for system installation/operation
• E+H Service.
Please refer to the tables in chap. 8.2 and 8.3 for identification of spare parts required.
Warning:
•
Disconnect the instrument from the
power source before opening it up.
Work with live lines may only be
performed by trained electricians.
•
Switched contacts may be
supplied from separate circuits.
These circuits must also be de-
energised before work on the
terminals is performed.
•
Caution: ESD!
Electronic components are
sensitive to electrostatic
discharges. Personal protective
measures, such as discharge via
PE or permanent grounding using
a wrist strap, are to be taken.
•
For your own safety, use only
original spare parts. Original parts
will guarantee functionality,
accuracy and reliability after
repairs.
8.1
Diagnosis
The table below will help you diagnose problems and specifies the spare parts required. You
can find information concerning the exact spare part designations and the installation of these
parts in Chap. 8.4.3 and 8.5.3.
Problem
Possible cause
Tests and / or remedial measures Equipment, spare parts, personnel
Display dark, no LEDs
active
– No mains voltage
Test whether mains voltage is
available
Electrician / e.g. Multimeter
– Wrong supply voltage / voltage
too low
Compare mains voltage and rating
on nameplate
Operator
(utility company specification or
multimeter)
– Connection fault
Terminal not tightened;
insulation clamped in terminal;
wrong terminal used
Electrician
– Instrument fuse defective
Replace fuse,
Also compare mains voltage and
nameplate rating
Electrician /
suitable fuse;
See Figs. Chap. 8.4.1 and 8.5.1
– Power unit defective
Replace power unit,
you must check variants
On-site diagnosis by E+H Service
(LSGx module required for test)
– Central module defective
Replace central module,
you must check variants
On-site diagnosis by E+H Service
(LSCxx module required for test)
– COM 253: ribbon cable
Pos. 310 loose or defective
Check ribbon cable,
replace if necessary
See spare parts for COM 253
OM253D08.CHP
Liquisys M COM 223 / 253
Diagnostics and corrective maintenance
Hauser
59