Drum Motor Ewd - Electrolux T5675 N2 Service Manual

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DRUM MOTOR EWD

21:1 HEATSINK TOO HOT
This error code is generated by the MCU for drum motor.
There is a temperature sensor (NTC) mounted on the MCU cooling flange next to the power transistors in the output
stage. If the temperature of the cooling flange gets too high (> 90°C) the error code will be set to protect the
transistors.
The cause of high cooling flange temperature can be e.g. a stiff drum in combination with intensive use and high am-
bient temperature. There may also be an error in the motor (sticking bearings or short circuit in windings, which im-
pairs the efficiency of the motor).
Recommended actions:
1. Make sure the drum turns easily.
2. Check the value on the error code counter for the error code.
3. Check the last 8 MCU error codes.
4. Start a 90°C normal program with load on continuous operation and measure the temperature of the motor and
MCU.
5. Replace the defective part.
21:2 MOTOR TOO HOT
This error code is generated by the MCU for the drum motor.
Each time the motor is started from stationary, the MCU will first measure the resistance between two phases in the
motor. The MCU processor governs the output transistors so that a DC current flows between two phases in the mo-
tor winding. The actuation of the transistors is a measure of the voltage applied to the winding and the resistance can
be calculated using the current and voltage values. The resistance can then be converted to a temperature since the
winding resistance at 20°C and the temperature coefficient are known. If the average value of the four latest tempera-
ture readings is higher than the maximum motor temperature (e.g. 150°C), the error code will be shown.
Possible causes:
The cause of high motor temperature can be a stiff drum, possibly in combination with intensive use and high ambi-
ent temperature. There may also be an error in the motor (sticking bearings or short circuit in windings, which impairs
the efficiency of the motor). There could also be a contact error in the connectors between the MCU and the motor or
an error in the motor cable. An error in MCU temperature measurement circuits can also occur.
Recommended actions:
• Make sure the drum turns easily.
• Check the value on the error code counter for the error code.
• Check the last 8 MCU error codes.
• Measure the three phases to the phase resistors on the MCU motor connector (disconnect MCU and take the
reading in the cable connector) to make sure they are the same.
• Start a 90°C normal program with load on continuous operation and measure the temperature of the motor and
MCU.
• Replace the defective part.
21:3 NO INTERLOCK
This error code is generated by the MCU for drum motor.
The MCU must be powered with 230V / 50 or 60 Hz on the interlock input in order to drive the motor. This signal is a
confirmation that the door is closed and locked.
MCU receives its commands to rotate the drum from the CPU via a serial communication link between the MCU and
CPU. Since the CPU also has access to the interlock signal, the CPU must never send a run command to the MCU if
the interlock signal is missing. If this does happen, this error code will be shown.
Possible causes:
The cause of this error code being activated can be e.g. a break in the cable leading the interlock signal to the MCU.
There may also be an error in the connector in the door lock, which connects 230V / 50 Hz to the interlock signal. An
error in the interlock circuits of the MCU can also set this error code.
Recommended actions:
1. Use a multimeter to check that the interlock signal is present on X302:1-2 when the door lock is activated. Read
also bit 1 in the second byte under MCU STATUS in the service program (the bits are numbered from 0 to 7 where
bit 0 is on the far right). If bit 1 in the second byte is 1 then the lock is open, while a 0 indicates that the lock is
closed.
Service Manual