Nikon SB-600 FSA03601 Repair Manual page 44

・Metering circuit:
This decides flash output based on the number of times, calculated by decreasing the preset constant electric current, each
time the electric charge, of which the light volume is integrated by the photo cell in the integral condensr of the integration
circuit, exceeds the threshold voltage.
・TG circuit:
This outputs the flash-start signals based on the flash-start command signals from the metering circuit, decoder circuit,
camera interface, and external slave circuit.
・STP circuit:
This outputs the flash-stop signals based on the flash-stop command signals from the metering circuit, decoder circuit,
camera interface, and external slave circuit.
・AF assist illuminator circuit:
This turns the illuminator on according to either the data received by the data communication from CPU or the lighting
signal from the CRY terminal. The illuminator turns off according to the CPU command. In addition, there is a terminal
prepared for SC-29 with the AF assist illuminator function. When SC-29 is attached, the built-in detection circuit
automatically lights up the AF assist illuminator of SC-29, while the AF assist illuminator of SB does NOT ligtht up.
・Data communication circuit:
This is the control circuit for sending/receiving signals from camera to communicate data via camera interface. The CPU
performs various settings or controls based on this data.
・Buzzer drive circuit:
This is the control circuit for sounding an external buzzer. The buzzer tone, pattern, etc are controled by the CPU.
・CPU:
This controls, etc the following: data communication control with camera via the custom IC; data communication control
for setting data to the custom IC; reading of switches; power-supply control; AF assist illuminator control; LCD indications;
motor drive circuit; voltage detection of the main condenser; turning ready-light to ON/OFF; EEPROM control; turning EL
to ON/OFF; slave circuit control, etc.
・Ready-light:
This lights up by the CPU when the voltage reaches the ready-light illumination. The CPU judges the charging voltage
by A/D conversion of the voltage output from the voltage detection circuit. At the same time, signals to illuminate the
ready-light in the camera finder are sent to the custom IC via 5-bit data communications.
・Remote circuit:
This reveives pulse-emission communications transmitted by the master speedlight, then converts them to pulse signals to
send to CPU via the custom IC.
・EEPROM:
This memorizes information such as status set by the switch input circuit, information necessary for the metering circuit, set
value of the timer circuit, etc.
- E2･ SB-600 -
FSA03601-R.3629.A