Sinclair SCV-750EB Service Manual page 96

L0: Inverter module protection
The DC bus wire connected incorrectly
Disconnect
the power
supply
The inverter module is not well heat
Ensure enough The compressor has less than 12 hours
Yes
preheating time
Note:
1. Make sure wire connection of CN38 port of compressor inverter module board is firm. Plug or pull out the wire under live working is not allowed.
How to determine whether the compressor module is damaged?

IPM internal rectifier circuit
Three phase rectifier measure

Set the multimeter to diode position. After unit power off for 10min, put the black pin on CN5(P_OUT) and put the red pin on CN6(L1)、CN7(L2)、CN11(L3)
respectively. If the voltage value is 0V, it means the three phase rectifier bridge reactor is damaged. Similarly, put the red pin on CN38 (N) and put the black pin
on CN6 (L1), CN7 (L2) and CN11 (L3) respectively. If the voltage value is 0V, it means the three phase rectifier bridge reactor is damaged.
Inverter circuit measure

Set the multimeter to diode position. After unit power off for 10min, put the black pin on CN1(P_in) and put the red pin on CN12(U)、CN13(V)、CN14(W)
respectively. If the voltage value is 0V, it means the IGBT or freewheel diode is damaged. Similarly, put the red pin on CN38 (N) and put the black pin on CN12 (U),
CN13 (V) and CN14 (W) respectively. If the voltage value is 0V, it means the IGBT or freewheel diode is damaged.
94
L0 protection
No
The compressor wiring is connected
incorrectly
No
The resistance between 3 phases of
compressor is over 5Ω
No
The insulation resistance of
compressor is less than 100kΩ
No
dissipation
No
preheating before initial operating
No
Switch on power again to detect
whether the compressor can start
Yes
Refer to "P3 over current protection" Refer to P4/P5 troubleshooting
Yes Ensure the wire is
1
connected properly
Yes Reconnect the cables
based on wiring diagram
Yes
Replace the compressor
Yes
Yes
The IPM screws is loosen
No
The silica gel is coated not
well for heat radiation
No
No
Replace the inverter
module
IPMM internal inverter circuit
Yes
Fasten IPM
screws again
Yes
Coat with silica
gel