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JOHNSON CONTROLS
128
FORM 150.63-NM6 (1020)
Service and Troubleshooting
ANALOG INPUTS – Pressure
Refer to the unit wiring diagram. Pressure inputs are con-
nected to the microboard on plugs J4 and J7. These
an-
alog
inputs represent varying dc signals corresponding
to varying pressures. All voltages are in reference to the
unit case (ground).
System 1 discharge and suction pressures will be con-
nected to J4 of the microboard. System 2 discharge and
suction pressure transducers will be connected to J7 of
the microboard.
The discharge transducers are optional on all units. If the
discharge transducers are not installed, no connections
are made to the microboard and the discharge pressure
readout on the display would be zero.
The suction pressure transducers are optional on
YCUL0045 - YCUL0185. If the suction transducers are
not installed, a mechanical low pressure switch will be
installed in its place, and the suction pressure readout
on the display will be 0 PSIG when the LP switch is
open, and 200 PSIG (13.79 BARG) when the LP switch
is closed.
The discharge transducers have a range from 0 to 400
PSIG. The output will be linear from .5
VDC
to 4.5
VDC
over the 400 PSIG (27.5 BARG) range. Following is the
formula that can be used to verify the voltage output of
the transducer. All voltage reading are in reference to
ground (unit case).
V = (Pressure in PSIG x .01) + .5
or
V = (Pressure in BARG x .145) + .5
where V = dc voltage output
Pressure = pressure sensed by transducer
The microboard connections for the Discharge
Transducers:
System 1 Discharge Transducer
J4-7
= +5VDC
regulated supply to transducer.
J4-12
=
VDC
input signal to the microboard. See the
formula above for voltage readings that
correspond to specific discharge pressures.
J4-8
= +5VDC
return
J4-9
= drain (shield connection = 0
VDC
)
System 2 Discharge Transducer
J7-7
= +5VDC
regulated supply to transducer.
J7-12
=
VDC
input signal to the microboard. See the
formula above for voltage readings that cor
respond to specific discharge pressures.
J7-8
= +5VDC
return
J7-9
= drain (shield connection = 0
VDC
)
Summary of Contents for YCUL0045
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