Micromod Micro-DCI: 53IT5100A Indicator/Totalizer - Manual (Page 57)

5.0 MAINTENANCE
NOTE
The factory set calibration constants for ANI0-3 and ANO0 are
applicable only for the main printed circuit board supplied in the
particular instrument. This data is recorded on a calibration sheet
supplied with the instrument. The data should be retained to facilitate
easy field recalibration in the event one or more of the constants is
inadvertently changed.
5.1 SERVICE APPROACH
This instrument is a microprocessor based device; all mathematical computations, data manipula-
tion, and sequencing operations are software controlled. After the instrument has been configured,
normal operations are controlled via the front panel push buttons. Because the instrument does not
have internal circuitry that requires field adjustment, diagnostic testing and preventive maintenance
are not required.
Generally, when a process malfunction occurs, it usually manifests itself as an instrument problem
even though it might be a defective process variable monitoring device, remote transmitter, or in-
terconnecting wires. These associated remote devices should be checked before attempting instru-
ment troubleshooting and repair.
Due to the complexity of microprocessor based instruments, attempting fault finding analysis to in-
tegrated circuits (ICs) on the main printed circuit board (PCB) is not recommended. The ICs are
static sensitive and can be damaged if not properly handled. Also, when test probes are con-
nected, even a momentary short across several IC pins with a probe tip can damage the IC. There-
fore, only trained technicians familiar with CMOS technology and microprocessor functionality
should be permitted to service the equipment.
5.2 PARTS REPLACEMENT
WARNING
ALWAYS REMOVE POWER BEFORE ATTEMPTING TO INSTALL,
DISASSEMBLE, OR SERVICE ANY OF THE EQUIPMENT. FAILURE TO
REMOVE POWER MAY RESULT IN SERIOUS PERSONAL INJURY
AND/OR EQUIPMENT DAMAGE.
Access to internal instrument parts is achieved by removing the front display panel. The front dis-
play panel can be removed by inserting a small screwdriver into the notch at the top center of the
display and twisting the screwdriver to depress the retaining latch. The upper sides of the display
are held and pulled forward as the latch is depressed. The cable at the rear of the front display
panel is disconnected from its socket. The other cable end connects to the main printed circuit
board. Replacing the display unit requires reconnecting the display end of the cable to the new
front display panel, inserting the extended portion of the display panel into the instrument cabinet
and latching it in place with a screwdriver.
Section 5. Maintenance
5-1