Metz mecablitz 40 MZ-2 Servicehandbuch Seite 36

Technik und Service Seite: 36
Technology and Service Page: 36
mecablitz 40 MZ-2
ENGLISH
Exposure control signal:
A high level of the exposure control signal indicates that the exposure was correct. This information
is sent to pin 47 of IC301 and via transistors Tr522/Tr523 (which convert the signal level to match the
SCA specification) to SCA contact 4.
The exposure control signal can be set by IC301 via the serial interface, internally in automatic flash
mode or by the TTL end pulse in TTL flash mode. It is reset by a signal from IC301 or by the Syn signal
at pin 3 of IC504.
Flash ready signal:
In flashguns with a serial number of 170 801 and higher, a high signal is present at pin 21 of IC504
when the flash is ready. Transistor Tr521 now receives a base voltage via the voltage divider R519,
R558 and R559 and conducts, pulling SCA contact 8 down to 0V.
In flashguns with a serial number lower than 170 801, the flash ready signal is controlled directly by
IC301: a low signal appears at pin 19 of IC301 when the flash is ready. The digital transistor Tr526
conducts, Tr521 receives a base voltage via the voltage divider R558/R559 and conducts, and 0V
appears at SCA contact 8.
Control of the supply voltage for the SCA 3000 adapter:
By setting and resetting pin 22 of IC504 via the serial interface, IC301 can switch the supply voltage
for the SCA 3000 adapter at SCA contact 13 on and off. Pin 22 low means "supply voltage off", pin
22 high means "supply voltage on".
The voltage at pin 22 is used as a reference for regulation of the voltage at SCA contact 13. A low
signal at pin 22 causes transistor Tr516 to conduct, which means that the voltage at its emitter is
approximately 0.7V. This voltage is also present at the base of Tr515, and the voltage at its emitter is
thus approximately 0V. With a high signal at pin 22, the voltage at the emitter of Tr516 is
approximately 5.7V and that at the emitter of Tr515 is 5V.
TTL flash control:
If the flash mode TTL or Remote TTL Controller is set on the flashgun, the IGBT can be switched off
with a positive pulse at SCA contact 7, from which it passes via Tr517 to pin 20 of IC504.
Cordless TTL flash control (slave):
In the flash mode Remote TTL Slave, the IGBT can be controlled via SCA contact 14 (low = IGBT on,
high = IGBT off) once a flash has been triggered. The control signal for this passes via Tr518 to pin 23
of IC504.
Control of the Canon aperture resistors: