Sinclair SCV-750EB Service Manual page 153

Procedure
Check whether the IPM virtual welding and the PWM related transmission circuit of the MCU are connected to the welding.
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If so, change the replace the drive board.
6.22 L6F: Open circuit of W-phase lower tube
Description
Open circuit of W-phase lower tube.
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After the fault, the compressor stops running, and if the fault disappears after one minute, the compressor starts again.
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Trigger/resume condition
Trigger condition: Open circuit of W-phase lower tube corresponding to compressor.
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Resume condition: Check whether the IPM module is working.
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 Reset method: Change the module board. Power on and start up again.
Possible causes
There IPM module is damaged.
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Procedure
Check whether the IPM virtual welding and the PWM related transmission circuit of the MCU are connected to the welding.

If so, change the replace the drive board.
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