York YCAV0157 Installation Operation & Maintenance page 213

TP3
+5V
TP2
+3.3V
SD
Card
JP4 JP5 JP6 Remote
Setpoint Jumpers
NEW 331-03478-XXX MICROBOARD
If the chiller control is malfunctioning, the power sup-
ply test points should be measured to determine the sta-
tus of the microboard.
POWER SUPPLY TEST POINTS
TP1 GND (Measure TP2, TP3, TP4 and TP5 in refer-
ence to this Test Point)
TP2 +3.3V [3.2 to 3.4VDC] provides power to the pro-
cessors
TP3 +5V [4.8 to 5.2VDC] power communication ports
2,3 and 4 and analog sensors
TP4 +12V [11.64 to 12.36VDC] powers the display
and backlight and is regulated to become the +5V
TP5 +15V [11.3 to 16.6VDC] powers the analog out-
puts to the EEV valves
CONFIGURATION JUMPERS
The same configuration jumpers that existed on the
02478 are provided on the 03478.
JP4 Remote Temp Reset jumper position Pins 1 to 2
(left) = 4-20 mA, Pins 2 to 3 (right) = 0-10 VDC
JOHNSON CONTROLS
TP10 +24V TP5 +15V
U5 RTC/
Power
Status
BRAM
LED
LED
JP5 Remote Current Limit jumper position Pins 1 to 2
(left) = 4-20 mA, Pins 2 to 3 (right) = 0-10 VDC
JP6 Remote Sound Limit jumper position (Pins 1 to 2
(left) = 4-20 mA, Pins 2 to 3 (right) = 0-10 VDC
COMMUNICATION PORTS
TB3 Port 1 Native BAS RS-485.
SW1 RS-485 Biasing Switch for Port. Set to ON if Chill-
er is in an End Of Line position on the network.
U26 is the Port 1 RS-485 Driver Chip. It is socketed to
allow field replacement. RX1 and TX1 LEDs illuminate
to indicate Port 1 communications activity.
E-LINK
SW2 RS-485 Biasing Switch for E-link Port 2, should be
in the OFF position.
TB2 is the Port 2 RS-485 E-Link Communications Port.
RX2 and TX2 LEDs illuminate to indicate the Port
2 communications activity. U23 is the Port 2 RS-485
Driver Chip. It is socketed to allow field replacement.
J16 provides +12VDC to power the E-Link.
TP4 +12V
TP1 GND
Port 2
RS-485 to
Power LED
E-Link
FORM 201.21-NM1 (1223)
Port 1
Future
Native
BAS
U26 Port 1
RS-485 Driver
U18 VSD
RS-485 Driver
VSD RX
VSD TX
8
RS-232
to Printer
Port 2
RX2
TX2
U23 Port 2
RS-485 Driver
LD19331
213