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138
The suction transducers have a range from 0 to 200
PSIG (13.79 BARG). The output will be linear from .5
VDC to 4.5 VDC over the 200 PSIG (13.79 BARG)
range. Following is a formula that can be used to verify
the voltage output of the transducer. All voltage read-
ings are in reference to ground (unit case).
V = (Pressure in PSIG x .02) + .5
or
V = (Pressure in BARG x .29) + .5
where V = DC voltage input to micro
Pressure = pressure sensed by transducer
Following are the microboard connections for the Suc-
tion Transducer:
System 1 Suction Transducer
J4-5 = +5 VDC regulated supply to transducer.
J4-10 = VDC input signal to the microboard. See
Zable 33 for voltage readings that corre-
spond to specific suction pressures.
J4-1 = +5 VDC return
J4-2 = Drain (shield connection = 0 VDC)
System 2 Suction Transducer
J7-5 = +5 VDC regulated supply to transducer.
J7-10 = VDC input signal to the microboard. See
Table 33 for voltage readings that corre-
spond to specific suction pressures.
J7-1 = +5 VDC return
J7-2 = drain (shield connection = 0 VDC)
If the optional Suction Transducer is not used on the
YCUL0016 - YCUL0066, a Low Pressure switch will
be used. Following are the microboard connections for
the Low Pressure switch.
System 1 Low Pressure Switch
J4-5 = +5 VDC regulated supply to LP switch.
J4-10 = input signal to the microboard. 0 VDC =
open switch / +5 VDC = closed switch.
J4-2 = Drain (shield connection = 0 VDC)
System 2 Low Pressure Switch
J7-5 = +5 VDC regulated supply to LP switch.
J7-10 = input signal to the microboard. 0 VDC =
open switch / +5 VDC = closed switch.
J7-2 = Drain (shield connection = 0 VDC)
DIGITAL OUTPUTS
Refer to the unit wiring diagram and Table 42. The digi-
tal outputs are located on TB3, TB4, and TB5 of the
microboard. ALL OUTPUTS ARE 120 VAC with the
exception of TB5-3 to TB5-4. TB5-3 to TB5-4 are the
contacts that can be used for an evaporator blower start
signal (refer to Evaporator Control Contacts in section
on Unit Controls). The voltage applied to either of these
terminals would be determined by field wiring.
Each output is controlled by the microprocessor by
switching 120 VAC to the respective output connection
energizing contactors, evap. heater, and solenoids ac-
cording to the operating sequence.
120 VAC is supplied to the microboard via connections
at TB3-1, TB3-7, TB4-3, and TB4-7. Figure 14 illus-
trates the relay contact architecture on the microboard.
TABLE 33 – SUCTION PRESSURE
TRANSDUCER PRESSURE TO
VOLTAGE CONVERSION FORMULA
Control Service and Troubleshooting
Summary of Contents for MILLENNIUM YCUL0016SC
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