Circuitry - Nikon SB-800 Repair Manual

Circuitry

・Mechanism:
SB-800 consists of the Custom IC, 8-bit CPU, EEPROM and other peripheral circuitry as shown on Page E1.
・Battery:
4 size-AA batteries can be inserted internally in SB-800. Available types are alkaline manganese battery, NiCd battery,
nickel-hydrogen battery, lithium battery, nickel manganese battery. Manganese battery could be used, but the recycle time
gets extremely long so it is virtually unavailable. If prepackaged additional battery pack (SD-800) is attached, the recycle
time can be shortened. In this case, the same type of batteries as that of internal batteries should be used.
・Pressurization circuit:
This increases the voltage of internal batteries, and charges the main condenser up to the given voltage (330V).
・Voltage detection circuit:
This outputs the voltage of lighting ready-light and the voltage of stopping pressurization to the A/D input terminal of CPU.
・Safety circuit:
This always monitors the voltage of charging the main condenser when batteries are inserted, irrespective of power-supplyof
SB-800. In case the voltage reached the given voltage (350V), the light is forced to be emitted in order to prevent damages
to the main condenser.
・Flash control circuit:
This starts light-emitting of flash-tube based on the flash-start signal (TG circuit) output by the Custom IC, and stops
light-emitting based on the flash-stop signal (STP circuit). The flash-signal output by the safety circuit is irrelevant to the
status of the power switch.
・External power-supply connecting terminal:
This charges directly the main condenser (not illustrated) that accumulates flash energy of SB-800. This can be connected to
external power-suplies which are separately sold: SD-6, SD-7, SD-8A, Power bracket SK-6, SK-6A.
・Custom IC:
This consists of the data communication circuit, decoder circuit, camera interface, voltage monitoring circuit, metering
circuit, TG circuit, STP circuit, AF assist illuminator circuit, data communication circuit, and buzzer drive cirucit.
- E2 ･ SB-800 -
INC
FSA03501-R.3613.A