Power Zoom - Metz mecablitz 40 MZ-2 Servicehandbuch

Technik und Service Seite: 33
Technology and Service Page: 33
mecablitz 40 MZ-2
ENGLISH
of IC301. If the main reflector is moved, i.e. switch S001 or S002 is opened, and the secondary
reflector is off, this voltage rises to approximately 3V. If the main reflector is in its normal position,
and only the secondary reflector is activated, which means that switch S602 is open, the voltage at
pin 25 is approximately 2.25V. If all three switches are open, the voltage at pin 25 is 5V.

5.1.3. Power zoom:

The mecablitz 40 MZ-2 has a power zoom reflector with 6 positions in the range of 24mm to 85mm.
An electric motor moves the reflector with the aid of a spindle, and the direction of motion is
reversed by reversing the polarity of the motor voltage. This is controlled by IC301 via the stage with
transistors Tr101 to Tr106. A wiper contact and a row of resistors inform IC301 at pin 27 of the current
reflector position.
Pin 16 and 17 of IC301 control the zoom motor. If, for example, pin 16 is connected to ground, Tr102
receives a base voltage from the voltage divider R101/R343 and conducts. This connects the
resistors R107, R105 and R106 together to form a voltage divider which supplies transistors Tr105 and
Tr104 with a base voltage, causing them to conduct. Tr105 then connects one end of the winding
of motor M001 to the positive battery voltage and Tr104 connects the other end to ground.
If pin 16 is connected to ground, pin 17 always carries a positive voltage (5V), and this cuts off
transistor Tr101, which means that Tr103 and Tr106 are also cut off. To change the direction of motor
rotation, pin 16 is switched to 5V and pin 17 is connected to ground. This cuts off transistor Tr102 and
the following transistors Tr105 and Tr104. On the other hand, transistor Tr101 now receives a base
voltage from voltage divider R102/R344 and conducts. Transistors Tr103 and Tr106 are switched on
via R103, R109 and R110. The polarity of the voltage supplied to motor M001 is thus reversed, and
the motor runs in the opposite direction.
When the reflector reaches the desired position, the signals at pins 16 and 17 are reversed
momentarily and the motor stops abruptly.
The position of the reflector is interrogated via the analog input at pin 27 of IC301. Resistor R319 and
the resistors R111 to R115 form a voltage divider. Depending on the reflector position, the wiper
contact, which is connected to ground, changes the total value of the resistor chain R111 to R115.
This changes the voltage across the divider resistors and thus the voltage present at pin 27 of IC301.
5.2. ASIC and periphery:
ASIC is the abbreviation for Application-Specific Integrated Circuit. The ASIC is controlled by
microprocessor IC301 via a serial interface and controls, in turn, the converter stages, the triggering
of flashes, the IGBT, the automatic light output control and certain parts of the SCA interface.
Supply voltage:
The ASIC, IC504, receives a supply voltage of 5V at pins 17, 24 and 39. This voltage is provided by
the voltage regulator IC502 and is available as soon as batteries are inserted in the flashgun.
Reset: