Drum Motor Ewd - Electrolux T5675 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 ambient temperature. There may also be an error in the motor (sticking bearings or
short circuit in windings, which impairs 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 motor 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 temperature
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 ambient 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.
Troubleshooting