Johnson Controls YORK Tempo YLAA Series, Installation Operation & Maintenance

Page: 172 / 192

JOHNSON CONTROLS
172
FORM 150.72-NM1 (1020)
Service and Troubleshooting
FIG. 30 – I/O BOARD RELAY CONTACT
ARCHITECTURE
LD12722
The suction transducers have a range from 0 to 400 PSIG
(27.5 barg). The output will be linear from 0.5VDC to
4.5VDC over the 400 PSIG (27.5 barg) range. Following
is a 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 .02) + .5
or
V = (Pressure in barg x .29) + .5
where V = DC voltage input to microprocessor
Pressure = pressure sensed by transducer
Following are the I/O board connections for the Suction
Transducer:
System 1 Suction Transducer
J7-5 = +5VDC regulated supply to transducer.
J7-10 = VDC input signal to the microboard.
See the formula above for voltage readings that cor-
respond to specific suction pressures.
J7-9 = +5VDC return
J7-1 = drain (shield connection = 0VDC)
System 2 Suction Transducer
J9-5 = +5VDC regulated supply to transducer.
J9-10 = VDC input signal to the microboard.
See the formula above for voltage readings that cor-
respond to specific suction pressures.
J7-9 = +5VDC return
J7-11 = drain (shield connection = 0VDC)
Digital Outputs
Refer to the unit wiring diagram and Fig. 30 . The digital
outputs are located on TB7, TB8, and TB9 and TB-10 of
the microboard. ALL OUTPUTS ARE 120VAC with the
exception of TB8-6 to TB8-7 which are the contacts that
can be used for a remote evaporator pump start signal.
The voltage applied to either of these terminals would
be determined by field wiring.
Each output is controlled by the microprocessor by
switching 120VAC to the respective output connection
energizing contactors, evaporator heater, and solenoids
according to the operating sequence
(see Fig. 30)
.
120VAC is supplied to the I/O board via connections
at TB7-1, TB7-6, TB10-1, TB10-6, TB8-1 and TB9-1.
Fig. 30 illustrates the relay contact architecture on the
microboard.
SYS 1
COMP 1
TB7-2
SYS 1
COMP 2
TB7-4
SYS 1
COMP 3
TB7-5
TB7-3 LLSV 1
TB8-6
EVAP
PUMP
TB8-7
TB7
SYS 2
HGSV
TB10-7
SYS 2
FAN 2
TB10-8
TB10-9
TB10-10 SYS 2
FAN 4
TB10
TB8
TB10
SYS 2
COMPR 1 (4)
TB10-2
LLSV 2 TB10-3
SYS 2
COMPR 2 (5)
TB10-4
SYS 2
COMPR 3 (6)
TB10-5
TB7
SYS 1
HGSV
TB7-7
SYS 1
FAN 1
TB7-9
SYS 1
FAN 3
TB7-10
TB7-8
SYS 1
FAN 2
TB8-2
HEAT EXCH
HEATER