Lc Display; Buttons And Switches - Metz mecablitz 40 MZ-2 Servicehandbuch

Technik und Service
Technology and Service
Pin 43 Data in
Pin 44 Data out
Pin 45 Clock
Pin 46 Serial interrupt (connected to the clock line)
Pin 29 Bus request
The data input, pin 43, and the data output, pin 44, are connected together via transistors Tr303
and Tr305 to form a single data line and this is connected to terminal 11 of the SCA contact PCB.
The clock signal from terminal 12 of the SCA connector passes via transistor Tr304 to pins 45 and 46
of IC301. The bus request to the SCA adapter or the Test Set is connected from pin 29 of IC301 via
Tr301 to SCA contact 3.
Flash synchronization:
When a flash is triggered, i.e. when the sync switch in the camera connects contact 10 of the SCA
connector to ground or when the test button S313 is pressed, the digital transistor Tr310 conducts.
This supplies a base voltage for Tr302 and this transistor also conducts and connects the Syn input of
IC301 to ground.

5.1.1. LC display:

The mecablitz 40 MZ-2 has a specially designed LC (liquid crystal) display which is driven directly in
multiplex mode by IC301, using pins 1 to 9 and 54 to 80. The various segments are combined into
four groups, and these groups are selected with four control lines (backplanes, COM 1 to 4) from
pins 6 to 9 of IC301.
The LC display can be illuminated with the LEDs D306 to D311. A low signal at pin 14 of IC301
causes transistor Tr309 to conduct and to connect the battery voltage via fuse resistor R501 and
fuse S501 to the LEDs D306 to D311.

5.1.2. Buttons and switches:

IC301 interrogates the buttons and switches with its digital and analog inputs. Only the main switch
with its four positions OFF, Auto OFF, ON and Lock is connected to the digital inputs at pins 34 to 37
of IC301. The operating mode selector switch S301, the buttons S303 to S312, the swivel reflector
with switches S001 and S002, and the secondary reflector switch S602 are interrogated via analog
inputs.
The operating mode selector switch is interrogated via pin 24 of IC301, the resistors R303, R305,
R307, R313 and switch S301 forming a voltage divider. Depending on the position of S301, a specific
voltage value is present at pin 24 of IC301.
The buttons S303 to S307 and S308 to S312 are interrogated in two groups via pins 22 and 23 of
IC301. Again, pressing a button activates the related voltage divider and the corresponding
voltage value is present at the input to IC301.
The voltage divider consisting of R301, R302, the switches S001 (reflector horizontal) and S002
(reflector vertical), together with resistor R304 and the secondary reflector switch S602 (which are
connected in parallel to R302, S001 and S002) delivers a voltage of approximately 1.75V at pin 25
mecablitz 40 MZ-2
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Page: 32
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