Mitsubishi Electric PQHY-P72ZLMU-A Service Handbook page 96

[ III Heat source Unit Components ]
3. INV board
LED1
Inverter in normal operation (Lit) /Error (blinking)
SC-P10
Diode rectifier output (P)
Bus voltage check
terminal (P) Note2
IGBT (Rear)
FT-C
Bus voltage input (C)
SC-P2
Bus voltage input (P)
SC-N
Bus voltage input (N)
SC-L3
Input (L3)
1) 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 between FT-P and FT-N on INV Board has dropped to DC20V or less.
(It takes about 10 minutes to discharge electricity after the power supply is turned off.)
2) Faston terminals have a locking function. Make sure the cable heads are securely locked in place. Press the tab on the ter-
minals to remove them.
3) When the power is turned on, the compressor is energized even while it is not operating. Before turning on the power, discon-
nect 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 heat source unit. The liquid refrigerant in the compressor will evaporate by energizing
the compressor.
HWE15150
LED4
Lit during normal CPU operation
CN6
Open: No-load operation setting
Short-circuited: Normal setting
CT3
SC-L1
Current sensor (L3)
Input (L1)
- 87 -
CN2
Serial communication signal output
GND (Control board)
GND (Control board)
17 VDC input
17 VDC input
SC-L2 CT12
Input (L2)
Current sensor (U)
CN4
1
GND (Control board)
2 Serial communication
signal input
CNTYP
INV board type output
RSH1
Overcurrent detection
resistor
Bus voltage check
terminal (N)
Note2
SC-V
Inverter output (V)
SC-W
Inverter output (W)
SC-U
Inverter output (U)
CT22
Current sensor (W)
GB