Micromod Micro-DCI: 53IT5100B Micro-DCI 4-Channel Indicator Totalizer - Manual (Page 47)

53IT5100B Indicator/Totalizer
INSTRUCTION MANUAL
43
5 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 manipulation, 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 interconnecting
wires. These associated remote devices should be checked before attempting instrument troubleshooting and
repair.
Due to the complexity of microprocessor based instruments, attempting fault finding analysis to integrated
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 connected, even a momentary short
across several IC pins with a probe tip can damage the IC. Therefore, 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 display 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.
After the front display panel is removed, the main printed circuit board can be accessed. The main printed
circuit board also has the power supply as well as the microprocessor circuitry. To remove the main PCB, use
its front edge board ejector to pull it free from the rear terminal board slot and carefully slide it from the case.
Disconnect the front display panel flat ribbon cable from the main PCB. The replacement main PCB can now
be installed by connecting the front display panel ribbon cable, sliding the PCB into the instrument case,
seating it into the rear terminal board slot, and installing the front display panel.
 NOTE: Power Supply Fuses
AC Power: 1A, 250 V, Fast Blow Schurter Type 034.3930
DC Power: 3A, 250 V, Slow Blow BEL Type 5TT3
For additional information, contact MicroMod Automation.