J31 High Bus Voltage Fault - Midea V8 VRF Series Service Manual

6.1.49 J31 - High bus voltage fault
Error display
The faulty IDU stops. Other IDUs of the same system: operate normally.
Error impact
ODU of the same system: operate normally.
Error trigger
When the bus voltage (DC voltage) is greater than the threshold value of the driver (450V)
Error recovery
Automatic recovery
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Possible cause
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Note:
1. Please refer to the figure below when measuring voltage between P and N. Make sure P/N
measuring points are selected according to PCB type.
Troubleshooting
2. Please observe the following rule when replacing the fan drive board: For units whose fan drive
board is welded onto the main control board, if either the fan drive board or main control board
becomes faulty, the whole control board has to be replaced.
Digital display
The input voltage is too high, resulting in high bus voltage.
Instantaneous high input voltage.
The fan drive board is damaged, so the bus voltage detection circuit becomes abnormal.
The IDU main control board is damaged.
Cause 1: Measure the input voltage of
IDU. If the voltage is significantly higher
than the normal value ( 318 V) or the
voltage increases instantaneously, the
Cause 2: If the input power supply is
normal, and the voltage (DC) between
P and N is normal (the normal voltage
J31
is about 310 V), it indicates that the
voltage detection circuit for fan drive
Cause 3: If the error cannot be cleared
after causes 1/2 have been eliminated,
the main control board of the IDU is
PCB type 1
P/N measuring point
N
P
Panel or display box
Spot check interface
query
power supply is abnormal
board is abnormal (1)
damaged
PCB type 2
P/N measuring point
(front of PCB)
V8 VRF Indoor Units
Display position
Wired controller
Error code is not
displayed
Fix the power supply
Replace the fan drive
board (2)
Replace the main
control board of the
IDU
P/N measuring point
(back of PCB)
P
P
N
97