Ac Drive Board - Ricoh FT7770 Service Manual

8. AC Drive Board

The ac drive board controls many of the ac motors used in this machine.
The circuit operation begins when RA102 energizes. At that time, 100 volts
ac is input into the ac drive board at CN313-1. Power is then distributed
to all solid state relays (SSRs).
Additionally, +24 volts is input to the ac drive board at CN212-1. The +24
volts is also distributed to all SSRs.
The SSRs act as switches, holding the 100 volts ac off and keeping the mo-
tors from operating. For a motor to energize, the main board CPU provides
Low to the dc trigger. This causes the SSR to turn on and 100 volts ac is
applied to the motor. When the CPU removes the Low from the trigger, the
SSR turns off and power is cut off from the motor.
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April, '89