Liebert himod - Control Circuit Board; LCD Display Contrast; Non-Volatile Memory; DIP Switches

14 Operation with Advanced Microprocessor Controls
2.8 Control Circuit Board
The control circuit board is located inside the unit behind the LCD display and control key panel.
Open the front panel for access to the board.
The control board includes an adjustment for LCD display contrast, nonvolatile memory, DIP
switches (which should not require customer changes), control output LEDs and jumpers for board
configuration. The jumpers should be placed as follows:
P5—removed
P12—removed
P19—installed on Pins 1 and 2
P47—installed on Pins 1 and 2
P48—installed on Pins 1 and 2
P50—all jumpers installed for 4-20 mA analog inputs. See 4.5.1 - Connecting the Analog Sen-
sors for other configurations
P51—removed
2.8.1 LCD Display Contrast
The level of contrast due to viewing angle of the LCD display can be adjusted using a small thumb
wheel at the upper left of the control board just under the cable going to the display. The control is
labeled R6.
2.8.2 Non-Volatile Memory
All critical information is stored in nonvolatile memory. Setpoints, setup parameters, and component
run hours are kept inside the microcontroller in EEPROM. Information retained for the alarm history
is kept in non-volatile RAM.
2.8.3 DIP Switches
Equipment options are selected and enabled using DIP switches 1 to 7. These are located at the upper
left of the control board and are labeled SW1. Switch 1 is at the top. These switches are factory set
and should not require any user changes. The setting and function of the switches can be read from
the LCD display (see Show DIP Switches on page 8 or the accompanying Table 4).
2.8.4 Control Outputs
Active control outputs are indicated with LEDs on the lower section of the control board. Each LED is
lit if the control output is active (on). The LEDs assist in troubleshooting the system. Refer to the fol-
lowing table.
NOTE
The LED backlighting on the text (4 x 20) display is always lit.
Table 6 Control output LEDs
LED Control Output
R5 Heat Rejection
LLSV Liquid Line Solenoid Valve
HGBP Hot Gas By-Pass or Compressor Unloader Valve
C1 Compressor
RH1 Reheat Stage 1, Hot Gas, Hot Water Reheat Solenoid or SCR Reheats
RH2 Reheat Stage 2
HUM Humidifier
FAN Main Fan
HMV Humidifier Make-Up Valve
LLSV2 Part Coil Solenoid Valve
HGBP2 Low Speed Fan (DEHUM)