S0740 800 196/E101019/P76
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ca41f2pwr
Checking secondary board 15AP2
Disconnect the machine from the mains and follow the instructions below. The item
numbers below refer to the circuit and component position diagrams on this and next page.
Checking the diode modules
1. Remove the screws marked 1a and 1b.
see this and next page.
a. Insert a thin insulating material
between connection T11 and
transformer 15TM1.
b. Insert a thin insulating material
between connection T22 and
transformer 15TM2.
S Be very careful when inserting the
insulation. If the board is bent too
much, the components on it will be
destroyed.
2. Use a multimeter in diode test position.
a. Measure with the positive and negative
of the multimeter connected as shown
in the pictures.
The forward voltage drop of the diodes must be 0.2 to 0.45 V. The voltage drop
over the freewheel diodes is slightly lower than the voltage drop over the rectifier
diodes. This because the freewheel diodes are connected in parallel.
b. Remove the insulation between the transformers and the circuit board. Refit the
screws, 1a and 1b, tighten the screws on the circuit board to the torque that is
shown in the picture on page 56.
Checking the NTC resistors
The NTC resistors that senses the temperature
are connected in a resistance network.
3. When the temperature of the diode module is
20_C, the resistance between pins 3 and 4 is
about 1.8 kohm.
Depending of the temperature of the module,
the resistance may be in the range of 0.5 to
10 kohm. The treshold level for
overtemperature is 390 ohm.
Both NTC resistors must have the same
resistance value.
4. NTC_R28 is fitted on the cupper foil of the
circuit board. When the temperature is 20_C,
the resistance is about 2.3 kohm.
Depending of the temperature, the resistance
may be in the range of 0.5 to 10 kohm.
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