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Action
• If the error is a stable one, it is generally not difficult to locate the defective unit through resistance
measurement and testing with the service program.
• Further information can be obtained by studying the contents of ”MCU FAULT LOGGER”.
Study the following:
SHORT CIRCUIT 2 (specifies how many times the error code has been active).
SHORT CIRCUIT 1 (specifies how many times the current limit has been exceeded. The
difference between short circuit 1 and short circuit 2 indicates how many times there has been a
short circuit 1 that has not been confirmed when restarting the motor).
LAST FAULT CODE N/8 (shows the 8 latest error codes).
TACHO CUT-OUT LOW RPM (can give a clue in case of intermittent errors).
TACHO CUT-OUT HIGH RPM (can give a clue in case of intermittent errors).
21:6 INTERLOCK HARDWARE
This error code is generated by the MCU. The MCU must be powered with 230V / 50 or 60 Hz on
the interlock input in order to drive the motor. The interlock circuits in the MCU have been split into
two channels so that a component error in MCU cannot give a false confirmation that the door is
locked. These two channels are checked against each other. If this check gives an incorrect
result this error code will be activated.
The reason for this error code being activated can be attributed to an error in the interlock circuits
in motor control.
Action
• Replace MCU.
21:7 LOW DC VOLTAGE
This error code is generated by the MCU. The MCU constantly measures the voltage over the
mains input. If the voltage is too low (= falls below a certain limit), the MCU will shut off the current
to the motor. Once the motor has stopped (= the tacho sensor indicates that the motor is stationary),
the MCU checks to see whether the input voltage is still low. If it is, this error code is activated.
The reason for this error code being activated can be low mains voltage or that the machine’s on/off
switch has been operated in an unsuitable manner.
Further information can be obtained by studying the contents of ”MCU FAULT LOGGER”:
• UNDERVOLTAGE 2 (specifies how many times this error code has been active).
• UNDERVOLTAGE 1 (specifies how many times the voltage has dropped below the limit. The
difference between undervoltage 1 and undervoltage 2 indicates how many times there has been
an undervoltage 1 without it being confirmed when the motor has stopped).
• LAST FAULT CODE N/8 (shows the 8 latest error codes) Undervoltages can be registered
even during normal operation. Consequently, a small number of registrations need not mean
that there is an error in the MCU.
Action
• Check that the supply voltage is stable and never drops below nominal voltage - 10%.
• Check the fuses and cables.
• Check the supply voltage in the network cabling and at the MCU in the machine.
Summary of Contents for W555H
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