Micromod Micro-DCI: 53SL5100B Single Loop Controller - Manual (Page 89)

53SL5100B Single-Loop Controller
INSTRUCTION MANUAL
83
12
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.
12.1 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.
12.2 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.
To access the internal instrument parts by removing the front display panel:
1. Insert a small screwdriver into the notch at the top center of the display.
2. Twist the screwdriver to depress the retaining latch.
3. Hold the upper sides of the display and pull forward as the latch is depressed.
4. Disconnect the cable at the rear of the front display panel from its socket. The other cable end
connects to the main printed circuit board.
To replace the display unit:
1. Reconnect the display end of the cable to the new front display panel.
2. Insert the extended portion of the display panel into the instrument cabinet.
3. Latch 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 has the power supply as well as the microprocessor circuitry.
To remove the main PCB:
1. Use the PCB’s front edge board ejector to pull it free from the rear terminal board slot, and carefully
slide it from the case.
2. Disconnect the front display panel flat ribbon cable from the main PCB.
To install the replacement main PCB:
1. Connect the front display panel ribbon cable.
2. Slide the PCB into the instrument case, seating it into the rear terminal board slot.
3. Install the front display panel.
 NOTE: Power Supply Fuses
AC Power: 1A, 250 V, Fast Blow Schurter Type 034.3930