Mitsubishi Electric PUHY-HP72 Service Handbook page 76

[4-2 Outdoor Unit Circuit Board Components ]
(2) TNU
LED900
Lit: Relay drive power
Unlit: Relay drive power
SC-L1
Input (L1)
1) When opening or closing the front panel of the control box, do not let it come into contact with any of the internal 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 pins 1 and 5 of connector RYPN has dropped to 20 VDC or less. It takes about 10 minutes to discharge
electricity after the power supply is turned off.
2) A Faston terminal on the inrush current resistor has a locking function. Make sure the cable heads are securely locked in
place. Press the tab on the terminals to remove them.
3) Control box houses high temperature parts. Be well careful even after turning off the power source.
4) Perform the service after disconnecting the relay connector (RYFAN1, RYFAN2). Before plugging in or unplugging
connectors, check that the outdoor unit fan is not rotating and that the voltage across pins 1 and 5 of connector
RYPN 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.
5) After servicing, reconnect the relay connector (RYFAN1, RYFAN2) of the fan as it was.
6) When the power is on, the compressor or heater is energized even while the compressor is stopped. Before turning on the
power, disconnect all power supply wires from the compressor terminal block, and measure the insulation resistance of the
compressor. Check the compressor for a ground fault. If the insulation resistance is 1.0 M or below, connect all power supply
wires to the compressor and turn on the power to the outdoor unit. It is energized to evaporate the liquid refrigerant that has
accumulated in the compressor.
HWE18240_GB
CNRY
12 VDC
GND
is supplied.
(Power-supply
board)
is not supplied.
SC-L2 SC-L3
Input (L2) Input (L3)
LED1
Lit: Inverter operation
Blinking: Inverter error
LED4
Lit: Microcomputer is energized.
Unlit: Microcomputer is not energized.
IGBT (rear)
CT001
Current sensor
(Direct bus current)
CN2
Serial communication signal
Signal input
GND (MAIN circuit board)
Signal output
GND (MAIN circuit board)
CN19V
18 VDC
GND
CNCT2
Connects to ACCT
with lead wire
7
chapter 4 -