Nikon SB-800 Repair Manual page 46

・Data communication circuit:
This connects the CPU by 5-bit signal wires and STB terminal, totalling 6 signal wires. The moment the signal of STB
terminal turns OFF, this sets the address for the Custom IC, and the moment the STB terminal turns ON, this writes the data
in the Custom IC or reads the data that is set in the Custom IC.
・Decoder circuit:
This decodes the address and data that were received at the data communication circuit, and performs various settings for
internal each block.
・Camera interface circuit:
This makes electrical connections with camera through shoe. This sends/receives data to/from camera based on the signals
from CPU. This also controls input/output signals to each terminal of shoe contacts.
・Voltage monitor circuit:
This monitors the battery voltage in real time, and when the power volrage falls below a given voltage, it stops the
operations of the pressurization circuit temporarily.
・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 correspondence 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.
- E3 ･ SB-800 -
INC
FSA03501-R.3613.A