Mitsubishi Electric CAHV-R450YA-HPB Service Manual page 57

[ III Unit Components ]
3. INV board
CNCT1A
DC current sensor output
(CT3)
SC-L
Bus voltage output(P)
SC-L1
Input(L1)
SC-L2
Input(L2)
SC-L3
Input(L3)
SC-B
Bus voltage output(P)
SC-U
Inverter output(U)
SC-V
Inverter output(V)
SC-W
Inverter output(V)
F001
3.15A 250VAC fuse
When opening or closing the front panel of the control box, do not let it come into contact with any of the internal
1)
components.
Before inspecting the inside of the control box, turn off the power, keep the unit off for at least 10 minutes, and
confirm that the voltage across CN-P and CN-N has dropped to 20 VDC or less. It takes about 10 minutes to
discharge electricity after the power supply is turned off.
A Faston terminal on the inrush current resistor has a locking function. Make sure the cable heads are securely
2)
locked in place. Press the tab on the terminals to remove them.
Control box houses high temperature parts. Be well careful even after turning off the power source.
3)
Perform the service after disconnecting the connector (CNINV1, CNINV2) on the fan board. Before plugging in
4)
or unplugging connectors, check that the outdoor unit fan is not rotating and that the voltage across CN-P and
CN-N is 20 VDC or less. The capacitor may collect a charge and cause an electric shock when the outdoor unit
fan rotates in windy conditions. Refer to the wiring nameplate for details.
After servicing, reconnect the relay connector (CNINV1, CNINV2) on the fan board as it was.
5)
When the power is turned on, the compressor is energized even while it is not operating. Before turning on the
6)
power, disconnect all power supply wires from the compressor terminal block, and measure the insulation resis-
tance of the compressor.
Check the compressor for a ground fault. If the insulation resistance is 1.0 Mohm or below, connect all power
supply wires to the compressor and turn on the power to the outdoor unit. The liquid refrigerant in the compressor
will evaporate by energizing the compressor.
HWE22020
CNRY
LED102
12 VDC
1
Lit: Relay drive power is supplied
2 GND(control board)
Unlit: Relay drive power is not supplied
CNCT2
Connects to ACCT
with lead wire
CN19V
CNTH
DCL temperature
thermistor input
- 48 -
C100-C109
Smoothing capacitor
CN-P, CN-N
Bus voltage check points
R127
Overcurrent detection resistor
LED1
Lit: Inverter operation
Blinking: Inverter error
LED4
Lit: Microcomputer is energized
Unlit: Microcomputer is not energized
CNCT1B
DC current sensor input
CN2
Serial communication signal
Signal input
1
2 GND(control board)
Signal output
3
GND(control board)
4
1 18 VDC
GND
2
GB